The thought of an asteroid hitting Earth sounds like the plot of a disaster movie, but in 2026 it is a question that scientists study with calm precision rather than panic. Space rocks of every size cross our planet’s path constantly, and what actually happens when one arrives depends almost entirely on a single number: its diameter. The vast majority burn up harmlessly as shooting stars, a handful explode in the upper atmosphere, and only the rarest giants ever reach the ground with civilization-altering force.

This guide walks through exactly what an asteroid impact would do at each size, the most famous impacts in history, how often they occur, and how agencies like NASA and ESA now detect and even deflect dangerous objects. The tone here is deliberately factual and reassuring, because the science genuinely supports optimism.

What happens if an asteroid hits Earth?

When an asteroid hits Earth, its kinetic energy — a function of mass and velocity squared — is converted almost instantly into heat, light, and a pressure wave. Objects typically arrive at 11 to 72 kilometres per second, so even a modest rock carries the energy of many nuclear weapons. The outcome ranges from a fleeting fireball to global catastrophe, scaling sharply with diameter.

Smaller bodies never survive the journey. Earth’s atmosphere is a remarkably effective shield, decelerating and vaporising most incoming rock before it reaches the surface. The trouble only begins when an object is large enough to punch through that protection.

The three outcomes of an impact

• Burn-up: Pebbles to boulders (under a few metres) disintegrate as meteors. Dozens strike the atmosphere daily.
• Airburst: Tens of metres across, the object explodes in mid-air, releasing a shockwave but leaving little or no crater.
• Ground impact: Hundreds of metres and larger reach the surface, excavating craters and, at the extreme, triggering global effects.

How do impact effects change with asteroid size?

Asteroid impact effects scale dramatically with diameter because energy grows with the cube of size. Doubling an asteroid’s width multiplies its mass — and roughly its destructive energy — by about eight. That is why a 20-metre rock and a 140-metre one belong to entirely different threat categories, even though both sound small against the scale of a planet.

The table below summarises the well-studied relationship between size and consequence. These figures come from impact modelling and the historical record, and they are the foundation of how planetary defence experts prioritise threats.

The pattern is clear and oddly comforting: the truly dangerous objects are also the rarest, and the common objects are mostly harmless. The danger zone we watch most closely sits in the 140-metre-and-up range, where impacts are infrequent but consequential.

What were the most famous asteroid impacts in history?

History gives us three benchmark events that anchor the entire conversation about an asteroid hitting Earth. Each represents a different size class, and together they show how the science moves from local nuisance to planetary catastrophe.

Chelyabinsk (2013): the modern wake-up call

On 15 February 2013, a roughly 20-metre asteroid entered the atmosphere over Chelyabinsk, Russia, and exploded about 30 kilometres up. The airburst released energy equivalent to roughly 400–500 kilotons of TNT. No one was killed, but the shockwave blew out windows across the city, injuring around 1,500 people, mostly from flying glass. Crucially, the object arrived from the direction of the Sun and was never detected in advance — a gap that surveys are still working to close.

Tunguska (1908): the largest in recorded history

The Tunguska event flattened an estimated 2,000 square kilometres of Siberian forest — about 80 million trees — when an object perhaps 50 to 60 metres across detonated in the air. No crater was ever found, confirming it was an airburst. Had it struck over a major city, casualties would have been enormous. It remains the clearest illustration of why even a “small” near-Earth object deserves attention.

Chicxulub (66 million years ago): the dinosaur killer

The Chicxulub impactor, around 10 kilometres wide, struck what is now the Yucatán Peninsula in Mexico. It carved a crater more than 180 kilometres across and ejected enough debris to darken the skies worldwide, triggering an “impact winter” that ended the age of the dinosaurs. This is the event people picture when they imagine the worst — and it is also the kind of impact we can now be confident is not lurking undetected, because objects that large are easy to find and we have catalogued essentially all of them.

To understand where these intruders come from, it helps to know our cosmic neighbourhood. Our explainer on the structure of the solar system shows how the main asteroid belt between Mars and Jupiter feeds the population of rocks that occasionally wander inward.

How likely is an asteroid hitting Earth?

A civilization-threatening asteroid hitting Earth is extremely unlikely in any human lifetime, and — this is the key point — no known asteroid poses a significant impact threat for at least the next 100 years. That statement comes directly from NASA’s impact-monitoring systems, which continuously track every catalogued near-Earth object decades into the future.

Probability scales inversely with size. Small, harmless meteors arrive constantly; a Chelyabinsk-class airburst happens somewhere on the planet every few decades; a Tunguska-class event every few centuries; and a true global catastrophe only on timescales of hundreds of thousands to millions of years. Statistically, you are far more likely to be affected by ordinary natural hazards than by a space rock.

What about Apophis in 2029?

The asteroid 99942 Apophis, about 340 metres across, will make a famously close pass on 13 April 2029, sweeping within roughly 32,000 kilometres of the surface — closer than some geostationary satellites. It will be visible to the naked eye from parts of Europe, Africa, and Asia. To be absolutely clear: Apophis will miss Earth. Radar observations in 2021 ruled out any impact risk for at least a century. Far from a threat, it is a once-in-a-lifetime scientific and observing opportunity, which is why 2029 has been designated a year of international asteroid awareness.

How do we detect near-Earth objects?

We detect near-Earth objects using a global network of survey telescopes that scan the night sky for moving points of light, then refine each object’s orbit over time. When a new object is found, astronomers calculate its trajectory and project it forward; NASA’s automated Sentry system at the Center for Near-Earth Object Studies (CNEOS) flags any with even a remote chance of impact.

Surveys such as Pan-STARRS and the Catalina Sky Survey discover thousands of new objects each year. The headline achievement: more than 95% of the largest, most dangerous asteroids — those over one kilometre — have already been found and confirmed to be safe. The remaining effort focuses on the smaller but still hazardous 140-metre class, a gap that future space-based infrared telescopes are designed to fill.

Where the catalogue still has blind spots

• Sun-direction objects: Asteroids approaching from the daytime sky are hard to see, as Chelyabinsk demonstrated.
• Small dark rocks: Objects tens of metres across reflect little light and can stay hidden until close.
• Solution in progress: Infrared space telescopes positioned to look back toward the Sun will dramatically improve early warning.

Asteroids are only one class of wanderer. For how icy visitors differ from rocky ones, see our companion piece on comets and their orbits, which behave quite differently as they near the Sun.

What is planetary defence and does it work?

Planetary defence is the coordinated international effort to detect, track, and — if necessary — deflect an asteroid on a collision course, and in 2026 we know it works because we have tested it. The strategy rests on a simple principle: with enough warning, a tiny nudge years before a predicted impact is enough to make an asteroid miss Earth entirely.

NASA’s DART mission: proof it works

On 26 September 2022, NASA’s Double Asteroid Redirection Test (DART) deliberately crashed a spacecraft into Dimorphos, a 160-metre moonlet orbiting the larger asteroid Didymos. The goal was to measure whether a kinetic impact could change an asteroid’s orbit. The result exceeded expectations: Dimorphos’s orbital period was shortened by about 33 minutes — far more than the 73-second minimum NASA had set as success. The plume of ejected debris added extra push, proving the kinetic-impactor technique is not only viable but efficient. It was humanity’s first demonstration that we can actively alter an asteroid’s path.

ESA’s Hera mission: the follow-up survey

The European Space Agency’s Hera mission, launched in October 2024, is en route to the Didymos system to study the aftermath of the DART collision up close. By precisely measuring Dimorphos’s new orbit, the crater, and the asteroid’s mass and composition, Hera will turn DART’s one-off experiment into a repeatable, well-understood deflection technique. Together, DART and Hera form the first complete planetary-defence test campaign.

Other deflection concepts

• Kinetic impactor: Ram the asteroid with a spacecraft — proven by DART.
• Gravity tractor: Park a spacecraft nearby and let its gravity slowly tug the asteroid off course.
• Nuclear standoff: A last-resort option for very large objects or short warning times, detonating a device nearby to vaporise surface material and create thrust.

A first-hand note on how amateurs help

I’m Hamza Touhami, and I’ve been doing astrophotography since 2008. People are often surprised to learn that amateur observers genuinely contribute to near-Earth object science. When professional surveys discover a new asteroid, its orbit is initially uncertain — and that is where the amateur community steps in, supplying follow-up astrometry that pins the orbit down before the object fades from view. From my own remote rig, tracking a fast-moving target and timing its position is demanding but deeply rewarding work.

One of the most valuable amateur activities is occultation timing: recording the precise moment an asteroid passes in front of a background star. Combining timings from observers spread across a region lets astronomers reconstruct an asteroid’s exact size and shape — data that even large telescopes struggle to capture. It is a real example of how careful backyard work feeds directly into planetary defence, and it is part of why I keep pointing my equipment at the sky.

What should you actually do about asteroid risk?

For an individual, the rational response to asteroid risk is essentially nothing — beyond enjoying the science. The probability of being harmed by an impact in your lifetime is vanishingly small, the largest threats are already catalogued and cleared, and for the first time in history we possess a tested method to deflect a dangerous object. This is one global hazard where the trend lines are firmly positive.

If you want to engage productively, channel curiosity instead of fear. Follow CNEOS impact-monitoring updates, learn the night sky, or even join an occultation-timing campaign. Understanding our neighbours — from the major planets to the smaller bodies — turns a vague dread into informed appreciation.

Key takeaways

• Most asteroids burn up; only objects over ~140 metres are seriously hazardous.
• No known asteroid threatens Earth for at least the next 100 years.
• Apophis will pass close on 13 April 2029 but will not hit Earth.
• DART proved in 2022 that we can deflect an asteroid; Hera is studying the result.
• Amateur astronomers help by tracking and timing near-Earth objects.

To keep exploring the rocky frontier of our system, browse our growing guides on the asteroid belt and near-Earth objects and on the Moon’s own cratered history, which records billions of years of impacts that Earth’s weather has long since erased.

For authoritative, continually updated information, see NASA’s Planetary Defense Coordination Office, the ESA Planetary Defence programme, and the Britannica entry on Apophis.

Frequently asked questions

Could an asteroid destroy Earth?

No asteroid in the solar system is large enough to literally destroy the planet. Even the 10-kilometre Chicxulub impactor that ended the dinosaurs left Earth intact, though it caused a mass extinction. Such giant impacts occur only once every 100 million years or more, and no object of that size is on a collision course.

Will an asteroid hit Earth in 2029?

No. The well-known asteroid Apophis will pass extremely close to Earth on 13 April 2029 — within about 32,000 kilometres — but radar measurements have ruled out any impact for at least a century. The 2029 flyby is a safe, spectacular observing opportunity, not a threat.

What is the biggest threat from a small asteroid?

The main danger from a small asteroid is an airburst, like the 2013 Chelyabinsk event over Russia. A 20-metre rock exploding in the atmosphere can shatter windows and injure people across a city with its shockwave, even without forming a crater. Larger objects in the 60-metre Tunguska class can flatten forests over thousands of square kilometres.

Can we stop an asteroid from hitting Earth?

Yes, with enough warning. NASA’s DART mission proved in 2022 that crashing a spacecraft into an asteroid can change its orbit — it shifted the moonlet Dimorphos by about 33 minutes. Other methods, like a gravity tractor, could nudge an asteroid years in advance so it safely misses Earth.

How does NASA find dangerous asteroids?

NASA and partner surveys scan the sky nightly for moving objects, then calculate their orbits decades into the future. The automated Sentry system at CNEOS flags any object with even a tiny impact chance. Over 95% of the largest, most dangerous near-Earth asteroids have already been discovered and confirmed safe.

Meteor showers are nature’s most accessible celestial fireworks — brief streaks of light that flash across the night sky when Earth plows through trails of dust and grit shed by comets and a few rocky asteroids. You don’t need a telescope, a tracking mount, or a dark-sky permit to enjoy them; you just need a clear sky, a little patience, and the right night. I’m Hamza Touhami, and I’ve been chasing the sky as an astrophotographer since 2008, from light-polluted city rooftops to my remote imaging rig under the pristine Atacama skies at Deepsky Chile. In this guide I’ll explain exactly what causes meteor showers, walk you through the full 2026 meteor shower calendar, and share the practical field methods I use to both watch and photograph them.

What causes meteor showers?

Meteor showers are caused by Earth’s orbit carrying it through a stream of debris — mostly sand- to pebble-sized particles — that a comet or asteroid has scattered along its own orbital path. When a comet swings close to the Sun, solar heat vaporizes its ices and releases embedded dust. That dust spreads out into a vast, diffuse ribbon of material that lingers in space for centuries. Every year, like clockwork, our planet crosses these ribbons at the same point in its orbit, which is why each shower returns on roughly the same calendar date.

The individual particles are tiny. Most meteors you see are produced by grains no larger than a grain of rice. They hit the top of the atmosphere at staggering speeds — anywhere from 11 to 72 kilometers per second — and the friction-driven heating ionizes the air around them, producing the glowing trail we call a “shooting star.” The particle itself almost never reaches the ground; it vaporizes around 80 to 120 km up.

Comet debris versus asteroid debris

Most showers come from comets, but two of the year’s strongest are exceptions. The Geminids originate from 3200 Phaethon, a rocky near-Earth asteroid (or possibly a dormant comet), and the Quadrantids trace back to asteroid 2003 EH1. The denser, rockier nature of this material is part of why the Geminids produce such bright, slow, richly colored meteors. The Perseids, by contrast, come from comet 109P/Swift-Tuttle, and the Eta Aquariids and Orionids both spring from the most famous comet of all, 1P/Halley — Earth crosses Halley’s debris trail twice a year, producing two separate showers.

What are radiants and ZHR?

Two terms come up constantly in any meteor shower calendar, and understanding them changes how you observe. The radiant is the point in the sky from which a shower’s meteors appear to emanate. This is a perspective effect, like snowflakes seeming to stream toward your windshield from a single point as you drive. Showers are named for the constellation that hosts the radiant: the Perseids radiate from Perseus, the Geminids from Gemini, the Leonids from Leo.

The Zenithal Hourly Rate (ZHR) is the theoretical number of meteors a single observer would see per hour if the radiant were directly overhead and the sky were perfectly dark. It’s an idealized benchmark, not a promise. In the real world, light pollution, a low radiant, haze, and especially moonlight cut your actual count well below the quoted ZHR. A shower with a ZHR of 150 might realistically deliver 30 to 60 meteors an hour from a good dark site — still a wonderful show.

Why moonlight matters more than ZHR

After two decades of planning observing sessions, I’ll tell you the single most important factor isn’t the ZHR at all — it’s the Moon. A bright gibbous or full Moon will wash out all but the brightest fireballs, and a high-ZHR shower under a full Moon can be a disappointment. This is exactly why 2026 is such a special year for the Perseids: the peak falls right beside a new Moon, giving genuinely dark skies all night. Always check the lunar phase before you commit to a date.

What is the 2026 meteor shower calendar?

Here is the complete 2026 meteor shower calendar for the eight major annual showers, with approximate peak nights and ZHR values. Dates and rates are drawn from the American Meteor Society and the International Meteor Organization. Note that the Quadrantids, Lyrids, and Eta Aquariids listed below for early 2027 are included because they belong to the same annual cycle — for January through May 2026 those same showers peaked on near-identical dates.

If you only watch two meteor showers in 2026, make them the Perseids and the Geminids. Both combine high rates with favorable Moon conditions this year, and both are reliable performers that rarely disappoint.

The best meteor showers of 2026

• Perseids (Aug 12–13): The headline event of 2026. A new Moon on August 11 means dark skies all night — the best Perseid conditions in years. Expect bright, fast meteors and occasional fireballs from warm late-summer nights.
• Geminids (Dec 13–14): The strongest annual shower with a ZHR near 150. A thin waxing crescent Moon sets early, leaving the prime post-midnight hours dark. Meteors are bright, slow, and often colorful.
• Quadrantids (Jan 3–4): Capable of 120 per hour but with a razor-sharp peak lasting only a few hours, and 2026’s bright Moon hurts. A gamble, but rewarding if you time it right.
• Eta Aquariids (May 5–6): Halley’s debris produces swift meteors best seen from the southern hemisphere — ideal for observers near my Chilean rig.

How do you watch a meteor shower?

Watching a meteor shower well is mostly about preparation and patience, and it costs nothing. The gear that matters most is a reclining chair, warm clothing, and a thermos. Here is the routine I’ve refined over years of cold nights in the field.

Get to a dark sky. This is the biggest lever you can pull. Even a 30-minute drive away from city glow can multiply the number of meteors you see. Use a light-pollution map to find a Bortle 4 site or darker. If you’re planning a trip, the same dark-sky logic that drives my deep-sky imaging at Deepsky Chile applies to naked-eye meteor watching.

Time it for after midnight. The hours between roughly 2 a.m. and dawn are almost always best. After midnight your location rotates to face Earth’s direction of travel, so you sweep up meteors head-on at higher rates — the difference between evening and pre-dawn counts can be two- or three-fold.

Practical observing tips

• Let your eyes adapt. Give yourself a full 20–30 minutes in darkness. Avoid white phone screens entirely; use a dim red light to preserve night vision.
• Don’t stare at the radiant. Meteors near the radiant have short trails. Look about 40–60 degrees away from it, high in the sky, where streaks are longest and most dramatic.
• Lie back and take in the whole sky. A wide field of view beats narrow concentration. Binoculars and telescopes are the wrong tools here — meteors are fast and unpredictable, and your naked eyes cover far more sky.
• Dress for colder than you expect. Lying still for hours, even a mild night feels frigid. Blankets, hot drinks, and layers make or break a session.

How do you photograph meteor showers?

Photographing meteor showers is one of the most rewarding entry points into astrophotography because the technique is simple and the gear is forgiving. You don’t need the dedicated cooled cameras and the tracking mount I use for my faint galaxy work — a basic DSLR or mirrorless camera, a wide lens, and a sturdy tripod will catch meteors beautifully. The core idea is to leave the shutter open and let meteors fall into the frame.

Use a fast, wide lens. A wide-angle lens (14–24mm on full-frame) captures a large swath of sky, which dramatically increases your odds of catching a meteor. Open the aperture as wide as it goes — f/2.8 or faster is ideal. The wider the field and the faster the glass, the more meteors you record.

Camera settings that work

My go-to starting recipe for a dark site is straightforward. Adjust to taste based on your sky brightness.

• Manual mode, RAW format. Always shoot RAW so you can recover highlights and pull detail in editing.
• Aperture: f/2.8 (or your lens’s widest).
• ISO: 1600–3200 under truly dark skies; lower if there’s moonlight or light pollution.
• Shutter: 15–25 seconds. To avoid star trailing, apply the “500 rule” — divide 500 by your focal length for the maximum exposure in seconds (e.g. 500 ÷ 20mm = 25s).
• Focus: Switch to manual and focus carefully on a bright star using live view at maximum zoom. Autofocus will fail in the dark. Tape the focus ring so it doesn’t drift.

If you want to dial in the exposure precisely for your sky and gear, our astrophotography calculator suite can help you balance ISO, aperture, and exposure time, and the field-of-view calculator is handy if you ever shoot meteors through a longer lens.

Use an intervalometer and shoot continuously

The secret to meteor photography is volume. Meteors are random, so you fire off hundreds of consecutive exposures and hope a bright one streaks through your frame. Set an intervalometer (a cheap external timer remote, or your camera’s built-in interval shooting) to take back-to-back exposures all night with a gap of just one second between frames. Out of 400 exposures you might capture three or four good meteors — that’s a normal, successful yield. I let my rig run unattended exactly this way and review the take in the morning.

Stacking and processing your results

Because meteors appear in different frames, the classic composite image combines several meteor-bearing exposures over one clean shot of the sky. Pick your sharpest frame as the base, then layer in the frames containing meteors and mask everything except the streaks. For the background stars you can also stack multiple frames to reduce noise, the same fundamental noise-reduction principle behind deep-sky imaging. Software like Sequator, Starry Landscape Stacker, or a manual layer stack in Photoshop handles this well. Always preserve a wide foreground element — a tree line, mountain, or building — to give the meteors scale and a sense of place.

Where do meteor showers fit in the night sky?

Meteor showers are one thread in a much larger tapestry of objects moving through our skies. The comets and asteroids that supply meteoroid streams are themselves fascinating to track, and understanding them deepens your appreciation of every shooting star. If you enjoy the broader context, explore our growing guides to the solar system and the planets, and keep an eye out for our upcoming pages on comets — the very sources of most showers — along with the Moon (whose phase makes or breaks your viewing) and asteroids like Phaethon that feed the Geminids.

For authoritative, up-to-date data, I always cross-check peak timings against the American Meteor Society calendar and NASA’s meteor resources. These are the same references professional and amateur observers worldwide rely on each year.

Frequently asked questions

What is the best meteor shower in 2026?

The Perseids (peaking the night of August 12–13, 2026) are the standout, thanks to a new Moon that leaves skies dark all night. The Geminids (December 13–14) are technically the strongest with a ZHR near 150 and also enjoy favorable Moon conditions in 2026. Both are excellent choices for beginners and experienced observers alike.

What causes meteor showers?

Meteor showers occur when Earth passes through a trail of dust and debris left behind by a comet or asteroid. The tiny particles slam into our atmosphere at tens of kilometers per second and burn up, producing glowing streaks. Because Earth crosses the same debris stream at the same point in its orbit each year, showers recur on predictable annual dates.

Do I need a telescope to watch a meteor shower?

No — a telescope is actually the wrong tool. Meteors are fast and appear anywhere in the sky, so your naked eyes, which cover the whole sky at once, are ideal. The best equipment is a reclining chair, warm clothing, dark skies, and patience. Telescopes and binoculars have far too narrow a field of view to catch fleeting meteors.

How do I photograph a meteor shower?

Mount a DSLR or mirrorless camera with a wide, fast lens (around 14–24mm at f/2.8) on a sturdy tripod. Shoot in RAW, manual mode, ISO 1600–3200, with 15–25 second exposures. Use an intervalometer to fire continuous back-to-back frames all night, then composite the frames that captured meteors over a clean base image in editing.

What is ZHR in a meteor shower?

ZHR (Zenithal Hourly Rate) is the theoretical number of meteors a single observer would see per hour under perfectly dark skies with the radiant directly overhead. It’s an idealized benchmark — real-world counts are usually lower because of light pollution, a low radiant, haze, and especially moonlight. Treat ZHR as a relative measure of a shower’s strength rather than a literal prediction.

Hero image: Perseid meteor by Martin Mark, CC BY-SA 4.0, via Wikimedia Commons.

Eris is the distant, icy dwarf planet whose 2005 discovery directly triggered the demotion of Pluto in 2006, forcing astronomers to finally agree on a formal definition of the word “planet.” Out beyond Neptune, in the cold scattered disc of the outer solar system, Eris is so massive that it could not be ignored — and once it was found, our nine-planet picture of the cosmos could not survive intact.

I’m Hamza Touhami, and I’ve been photographing the night sky since 2008, running a remote rig under the dark skies of Chile. I’ll be honest from the start: Eris is one object you will almost certainly never image with amateur gear. At roughly magnitude 18.7 it is fainter than Pluto by a wide margin, sitting near the very limit of what large research telescopes resolve. But Eris is one of the most important objects in the solar system to understand, because more than any other body it reshaped how we define a planet at all.

What is Eris?

Eris is a dwarf planet orbiting in the outermost reaches of our solar system, far beyond Neptune. It belongs to a population of icy bodies called trans-Neptunian objects, and more specifically to the scattered disc — a region of highly elongated, tilted orbits flung outward by gravitational encounters early in the solar system’s history.

It is one of the largest known dwarf planets, comparable to Pluto in size but noticeably heavier. Its official designation is 136199 Eris, and it is named after the Greek goddess of strife and discord — a fitting choice, given the scientific argument the object provoked.

Where does Eris sit in the solar system?

Eris travels on a strongly eccentric orbit that carries it between about 38 and 97 astronomical units (AU) from the Sun, where one AU is the average Earth–Sun distance. At present it lies near the far end of that path, roughly three times farther from the Sun than Pluto’s average distance. A single orbit takes around 557 years. Its orbit is also steeply inclined, tilted about 44 degrees relative to the plane in which the major planets move — a hallmark of the scattered disc.

Who discovered Eris and when?

Eris was discovered in January 2005 by a team of three American astronomers: Mike Brown of Caltech, Chad Trujillo, and David Rabinowitz. They identified it in images taken at Palomar Observatory in California in 2003, where its painfully slow motion against the background stars had initially hidden it among countless fixed points of light.

The object was given the provisional designation 2003 UB313, but it quickly earned an unofficial nickname inside Brown’s team: “Xena,” after the television warrior princess. Its moon was nicknamed “Gabrielle.” Those informal names captured the excitement of the moment, because the team believed, correctly, that they had found something genuinely larger than expected.

Why was the discovery such a big deal?

For decades Pluto had been an awkward outlier: a small, icy world that did not resemble the rocky inner planets or the gas giants. As long as it appeared to be one of a kind, astronomers could treat it as a quirky ninth planet and move on. Eris destroyed that comfortable arrangement. Early measurements suggested it was actually larger than Pluto, and it was clearly just as much a planet — or just as little of one. Suddenly there was no logical way to call Pluto a planet without also crowning Eris the tenth. And if Eris counted, so might dozens of other large bodies waiting in the dark.

How did Eris demote Pluto?

Eris demoted Pluto by forcing astronomers to confront a question they had avoided for nearly 75 years: what, precisely, is a planet? The discovery created an immediate dilemma. Either the solar system gained a tenth planet, or the definition of “planet” had to be tightened in a way that would exclude both Eris and Pluto.

The International Astronomical Union (IAU) took up the issue at its General Assembly in Prague. On 24 August 2006, member astronomers voted to adopt a formal, three-part definition of a planet for the first time in history.

What is the IAU definition of a planet?

Under the 2006 resolution, a planet in our solar system must satisfy three conditions:

• It must orbit the Sun.
• It must have enough mass for its own gravity to pull it into a nearly round shape (hydrostatic equilibrium).
• It must have “cleared the neighbourhood” around its orbit of other comparable bodies.

Pluto and Eris meet the first two criteria but fail the third — both share their orbital zones with swarms of other icy objects. To classify them, the IAU created a new category: the dwarf planet. A dwarf planet orbits the Sun and is round, but has not cleared its orbital path. With one vote, the solar system dropped from nine planets to eight, and both Pluto and Eris became charter members of the new dwarf-planet club.

Was the decision controversial?

Extremely. The “cleared the neighbourhood” criterion remains debated to this day, partly because it is hard to define rigorously and partly because it depends on where an object orbits, not just on what the object itself is like. Many planetary scientists, especially those who study geology and atmospheres, argue that Pluto and Eris are planets in every meaningful physical sense. Mike Brown himself — the man who found Eris — embraced the role, later titling his memoir How I Killed Pluto and Why It Had It Coming. The naming of the object as Eris, goddess of discord, was a deliberate wink at the chaos it caused.

How does Eris compare to Pluto?

Eris and Pluto are remarkably similar twins, but with telling differences. Pluto is very slightly larger in diameter, while Eris is distinctly more massive and therefore denser. This is the detail that overturned the old assumption that Pluto was the “king” of the outer solar system.

Why is Eris denser than Pluto?

Because Eris packs about 27% more mass into a slightly smaller volume, its average density is higher — roughly 2.4 grams per cubic centimetre, compared with Pluto’s ~1.9. That suggests Eris contains a larger proportion of rock relative to ice in its interior. The two worlds likely formed from similar materials in the same region of the early solar system, but their internal recipes ended up subtly different.

What is the surface of Eris like?

Eris has one of the most reflective surfaces in the solar system, with an albedo near 0.96 — meaning it reflects almost all the sunlight that reaches it, comparable to fresh snow. This is thought to be a layer of methane and nitrogen ices that have frozen out of a thin atmosphere. As Eris moves along its enormous orbit and slowly approaches the Sun over the coming centuries, that frozen atmosphere may partially sublimate, much as Pluto’s does. Its extreme reflectivity is also why Eris confused early size estimates: a small, bright object can mimic a larger, duller one.

What is Dysnomia, Eris’s moon?

Dysnomia is the single known moon of Eris, discovered in October 2005 using the Keck Observatory in Hawaii. It is named after the daughter of the goddess Eris — Dysnomia, the spirit of lawlessness — continuing the family theme of strife.

Dysnomia is small and dark compared with its brilliant parent, and it orbits Eris roughly every 16 days. Despite its modest size, this little moon turned out to be scientifically priceless.

How did Dysnomia let us weigh Eris?

A moon is a natural gravity scale. By carefully tracking how Dysnomia orbits Eris — its orbital distance and period — astronomers could apply Kepler’s laws to calculate the combined mass of the system, and thus the mass of Eris itself. In June 2007 that calculation gave a figure about 27% greater than Pluto’s. Without Dysnomia, we would not have known that Eris is the heavier of the two. The same trick is how Pluto’s mass was pinned down using its large moon Charon. You can read more about Eris and its companion in NASA’s overview at NASA Science.

What is the scattered disc?

The scattered disc is a sparsely populated region of the outer solar system whose members travel on highly eccentric, steeply inclined orbits. It overlaps with the outer Kuiper Belt but extends much farther, and Eris is its best-known resident.

Objects ended up here through gravitational “scattering” — close encounters with Neptune in the solar system’s youth flung them outward onto stretched, tilted paths. This is different from the classical Kuiper Belt, where bodies follow more circular, orderly orbits closer to the plane of the planets.

How does Eris fit into the trans-Neptunian population?

Eris is part of a broad family of icy worlds collectively called trans-Neptunian objects — everything orbiting beyond Neptune. This family includes the Kuiper Belt, the scattered disc, and the distant detached objects. Eris, along with Pluto, Makemake, Haumea, and Ceres (the lone dwarf planet in the asteroid belt), demonstrated that our solar system is far more crowded with substantial worlds than the tidy “nine planets” model ever suggested. For the wider picture, see how these regions connect across the solar system as a whole.

Can you see Eris with a telescope?

Realistically, no — not with amateur equipment. Eris shines at roughly magnitude 18.7, which puts it beyond the reach of all but very large telescopes paired with long-exposure imaging and excellent dark skies. For context, Pluto at around magnitude 14 is already a serious challenge that defeats most backyard setups; Eris is far fainter still and currently sits near the most distant point in its orbit.

How do professionals study such a faint world?

Researchers rely on the largest ground-based observatories — Keck, the Very Large Telescope — and on space telescopes like Hubble. A particularly elegant technique is the stellar occultation, in which Eris briefly passes in front of a background star. By timing exactly how long the star winks out from multiple locations on Earth, astronomers measured Eris’s diameter with high precision — that is how we know it is about 2,326 km across, just slightly smaller than Pluto.

In my own work I focus on deep-sky targets that genuinely reward a remote rig — nebulae, galaxies, and the brighter outer-planet fields. I’d gently steer any astrophotographer away from chasing Eris and toward objects that are both achievable and spectacular. Eris belongs to a different category: a world to study, not to shoot. To compare it with a target that is imageable by dedicated observers, read about its more famous sibling, Pluto.

Why does Eris still matter in 2026?

Twenty years on, Eris remains the object that permanently changed our cosmic vocabulary. Every textbook that says “eight planets” says so because of what was found in those Palomar plates. The debate it ignited — over whether “clearing the neighbourhood” is a fair test, and whether dwarf planets deserve the name “planet” at all — is still very much alive among planetary scientists today.

No spacecraft has ever visited Eris, and given its distance, none is planned in the near term. That means almost everything we know comes from clever remote measurements: occultations, the orbit of Dysnomia, and spectroscopy of its icy surface. For an authoritative, regularly updated reference, the Eris entry on Wikipedia and Caltech’s own coverage of Mike Brown’s mass measurement are excellent starting points.

Frequently asked questions

Is Eris bigger than Pluto?

Not quite in diameter. Eris is about 2,326 km across, very slightly smaller than Pluto’s ~2,377 km. However, Eris is roughly 27% more massive than Pluto, making it the heavier of the two. Early estimates suggested Eris was larger, which is part of why its discovery caused such a stir.

Why did Eris cause Pluto to be demoted?

Eris was so similar to Pluto — and apparently larger at first — that astronomers could not call Pluto a planet without also adding Eris, and potentially many other large icy bodies. To resolve this, the IAU created a formal planet definition in 2006 that excluded both, placing them in the new “dwarf planet” category.

What is the name of Eris’s moon?

Eris has one known moon, Dysnomia, discovered in October 2005. It is named after the daughter of the goddess Eris in Greek mythology. By tracking Dysnomia’s orbit, astronomers calculated Eris’s mass and confirmed it is heavier than Pluto.

Who discovered Eris?

Eris was discovered in January 2005 by Mike Brown, Chad Trujillo, and David Rabinowitz, using images taken at Palomar Observatory in 2003. It was first nicknamed “Xena” before receiving its official name in September 2006.

Can amateur astronomers see Eris?

In practice, no. At about magnitude 18.7, Eris is far too faint for typical amateur telescopes and cameras. Even Pluto, which is much brighter, challenges most backyard equipment. Eris is best appreciated as an object to understand rather than one to observe or photograph.

The moons of the solar system are some of the most fascinating worlds an amateur astronomer can ever point a telescope toward, and after observing them for nearly two decades I still find myself returning to them night after night. I’m Hamza Touhami, and I’ve been an astrophotographer since 2008. Most of my deep-sky work now runs through a remote rig at Deepsky Chile — an Alluna 12.5″ Ritchey–Chrétien on a Paramount MX+ — but my love of astronomy began the old-fashioned way: with a small scope in my backyard, watching Jupiter’s four bright satellites shuffle position from one evening to the next. This guide covers how many moons there are, how they form, the largest moons, the strange ocean worlds, and exactly which ones you can see for yourself.

How many moons are in the solar system?

The honest answer to how many moons in the solar system there are is: it depends on the week you ask. Moon counts are a moving target because survey telescopes keep finding tiny, faint objects orbiting the giant planets. As of 2026, the total across all planets sits at roughly 400 confirmed natural satellites, and that number is still climbing.

Saturn took the crown as the moon king in recent years. Following discovery announcements in 2026, Saturn’s confirmed moon count reached the high 280s to around 290 — far more than any other planet. Jupiter, long the front-runner, now sits in the mid-90s to just over 100 depending on which newly confirmed objects you include.

Here is the rough state of play in 2026:

• Saturn: ~290 confirmed moons (the most of any planet)
• Jupiter: ~95–115 confirmed moons
• Uranus: ~28 moons
• Neptune: ~16 moons
• Mars: 2 moons (Phobos and Deimos)
• Earth: 1 moon (our Moon)
• Mercury and Venus: 0 moons

Dwarf planets have moons too — Pluto has five, including the surprisingly large Charon. Even some asteroids carry tiny moonlets of their own. If you want to see how these worlds fit into the bigger picture, our solar system overview maps out the planets, dwarf planets, and their families of satellites.

Why do Saturn and Jupiter have so many moons?

The gas giants dominate the moon count for one simple reason: gravity and mass. Jupiter and Saturn are enormous, so their gravitational reach is vast. Over billions of years they captured countless small bodies — chunks of rock and ice left over from the solar system’s formation, plus passing asteroids and fragments of larger moons that broke apart in collisions.

Most of these newly counted moons are tiny, often just one or two kilometres across, and incredibly faint. They orbit far from their parent planet, frequently on tilted or backward (retrograde) paths, which is the signature of a captured object rather than one that formed alongside the planet. They are utterly beyond the reach of any amateur telescope, but they tell a rich story about the chaotic early solar system.

The large, bright, round moons — the ones we actually care about visually — are a different population entirely. They formed in place, from the disc of gas and dust that surrounded each young giant planet, almost like miniature solar systems.

How do moons form?

Moons form through three main pathways, and understanding them explains why the moons of the solar system look so wildly different from one another.

Co-formation in a circumplanetary disc

The biggest moons of Jupiter and Saturn condensed from a swirling disc of material around the newborn planet. This is why the four Galilean moons orbit neatly in Jupiter’s equatorial plane in tidy, near-circular orbits — they grew up together in an orderly environment.

Capture

Many smaller moons were once independent bodies that strayed too close and were snared by a planet’s gravity. Neptune’s giant moon Triton is the most famous example, and we’ll come back to it. Captured moons often have eccentric, inclined, or retrograde orbits.

Giant impact

Our own Moon almost certainly formed when a Mars-sized body slammed into the early Earth, blasting debris into orbit that coalesced into the Moon. This is why the Moon’s composition resembles Earth’s outer layers. You can read more about Earth’s companion on our dedicated Moon page.

What are the largest moons in the solar system?

When people ask about the largest moons, the answer surprises them: the biggest moons are larger than the planet Mercury. Ganymede, Jupiter’s giant satellite, is the largest moon in the solar system at 5,268 km across. Titan, Saturn’s flagship moon, comes second. Both dwarf our own Moon.

The table below lists the seven biggest moons, including ours, with their parent planet and diameter. These are the heavyweights — everything else drops off sharply in size.

Ganymede is so large it even generates its own magnetic field — the only moon known to do so. It also hides a subsurface ocean of liquid water beneath its icy crust, a theme that turns out to be common among the outer moons. Britannica maintains a thorough reference on these satellites if you want deeper background on Jupiter’s moons.

What are the Galilean moons of Jupiter?

The Galilean moons — Io, Europa, Ganymede, and Callisto — are the four largest satellites of Jupiter, and they are the single best target for a beginning observer. Galileo Galilei discovered them in January 1610, and that observation helped overturn the idea that everything in the sky revolves around the Earth. Watching them yourself is, in a real sense, repeating one of the most important experiments in the history of science.

Each of the four is a world in its own right:

• Io: the most volcanically active body in the solar system, covered in sulphur and erupting lava plumes
• Europa: a smooth ice ball hiding a global saltwater ocean — a prime target in the search for life
• Ganymede: the largest moon of all, bigger than Mercury
• Callisto: an ancient, heavily cratered world with one of the oldest surfaces known

For a deeper look at the planet itself and its satellite system, see our guide to Jupiter.

What are ocean worlds, and which moons have them?

Some of the most exciting moons of the solar system are the ocean worlds — moons that hide vast oceans of liquid water beneath their frozen crusts. These are arguably the best places in the solar system to look for life beyond Earth.

Europa

Europa is the headline ocean world. Beneath its cracked, icy shell lies a salty ocean that may hold more water than all of Earth’s oceans combined. NASA’s Europa Clipper mission, launched in 2024, is on its way to study exactly this. NASA keeps an excellent overview of Jupiter’s moons for those who want mission-level detail.

Enceladus

Saturn’s small moon Enceladus stunned scientists when the Cassini spacecraft flew through geysers of water vapour and ice erupting from cracks near its south pole. Those plumes come from a subsurface ocean and even contain organic molecules.

Ganymede, Callisto, and Titan

Ganymede and Callisto are also thought to harbour internal oceans, and Titan has a subsurface water layer in addition to its bizarre surface lakes of liquid methane and ethane — the only other place in the solar system with stable surface liquid.

What makes Io and Triton so unusual?

Two moons stand out as the solar system’s great oddballs, and both reward a bit of study even though only one is realistically observable.

Io: the volcanic moon

Io is squeezed and stretched by Jupiter’s immense gravity and the tug of its neighbouring moons. This tidal flexing heats Io’s interior so intensely that it is the most volcanically active body known, with hundreds of active volcanoes spewing plumes hundreds of kilometres high. Its surface is constantly resurfaced, painted in yellows, oranges, and reds from sulphur compounds.

Triton: the backward moon

Neptune’s largest moon, Triton, orbits its planet backwards — a retrograde orbit, opposite to Neptune’s spin. No large moon that formed in place would do this. The strong consensus is that Triton was a captured body from the Kuiper Belt, the same icy region that hosts Pluto and the other trans-Neptunian objects. Triton is geologically active too, with nitrogen geysers and a young, icy surface, and it is slowly spiralling inward toward an eventual breakup.

Which moons can amateurs observe through a telescope?

This is where two decades behind the eyepiece pays off. The vast majority of the solar system’s moons are far too faint for amateur gear, but a handful are genuinely easy — and a couple more are achievable with patience and good skies.

The four Galilean moons of Jupiter

If you observe just one thing, make it Jupiter’s moons. Io, Europa, Ganymede, and Callisto appear as tiny “stars” strung out in a line on either side of Jupiter. You can see them in steadily held 10×50 binoculars, and in any telescope they are unmistakable. My first proper observation in the late 2000s was sketching their positions on consecutive nights; within a week you literally watch them orbit. Here are my practical tips:

• Use low to moderate magnification first — the moons are easiest to spot near the planet’s glare at around 50–100×.
• Look on different nights: the configuration changes hour to hour, and sometimes a moon hides behind Jupiter or transits across its face.
• Watch for shadow transits, when a moon casts a crisp black dot onto Jupiter’s cloud tops — one of the finest sights in amateur astronomy.
• Steady air (good “seeing”) matters more than aperture for this target.

Saturn’s Titan

Saturn’s largest moon, Titan, is comfortably within reach of a small telescope. At roughly 8th magnitude it shows as a modest point of light that orbits Saturn over about 16 days. Give your eyes time to settle, use enough magnification to pull it clear of Saturn’s ring glare, and you’ll find it without trouble. A 4″ scope shows it easily; a 6″ or larger will start to reveal fainter Saturnian moons such as Rhea, Tethys, and Dione on a good night. More on the ringed planet itself lives on our Saturn page.

Our own Moon

Don’t overlook the obvious. Earth’s Moon is the most detailed object available to any telescope, and the terminator — the line between lunar day and night — throws crater shadows into stunning relief. It’s the perfect first light for any new instrument.

Planning your view

Knowing whether a moon will fit comfortably beside its planet in your eyepiece is part of the fun. Our telescope field-of-view calculator lets you plug in your scope and eyepiece to preview exactly how Jupiter and its moons will frame up before you head outside. For a broader tour of what else is visible, browse our planets hub.

How are new moons still being discovered in 2026?

It might seem strange that we’re still finding moons in the 2020s, but modern survey telescopes are extraordinarily sensitive. Discoveries in 2026, confirmed through the International Astronomical Union’s Minor Planet Center, pushed Saturn’s tally to around 290 and added more to Jupiter’s count. These newly found objects are tiny — many around one to two kilometres wide and roughly a hundred million times fainter than the faintest star visible to the naked eye.

The discovery process involves taking many deep images of the region around a planet over several nights, then carefully tracking faint points of light that move together with the planet against the background stars. Once an object’s orbit is confirmed, it earns official moon status. The count will almost certainly keep rising as surveys go deeper.

Frequently asked questions

How many moons are in the solar system in 2026?

As of 2026 there are roughly 400 confirmed moons across all the planets. Saturn leads with around 290, Jupiter has about 95 to 115, Uranus around 28, Neptune about 16, Mars two, and Earth one. The total keeps rising as survey telescopes detect more small, faint satellites around the giant planets.

What is the largest moon in the solar system?

Ganymede, a moon of Jupiter, is the largest at 5,268 km in diameter — bigger than the planet Mercury. Saturn’s Titan is second at about 5,150 km, and Jupiter’s Callisto is third. All three are substantially larger than Earth’s Moon, which is 3,475 km across.

Can you see Jupiter’s moons with binoculars?

Yes. Jupiter’s four Galilean moons — Io, Europa, Ganymede, and Callisto — are visible in steadily held 10×50 binoculars as tiny points of light flanking the planet. A telescope makes them obvious and reveals shadow transits and changing positions from night to night. Bracing the binoculars against a wall or tripod helps a great deal.

Which moons might have life?

The leading candidates are the ocean worlds: Europa and Enceladus, both of which hide liquid-water oceans beneath icy crusts, with Enceladus actively venting water and organic molecules into space. Ganymede, Callisto, and Titan are also of interest. None has confirmed life, but these subsurface oceans are the most promising places to search beyond Earth.

Why does Triton orbit Neptune backwards?

Triton orbits Neptune in a retrograde direction — opposite to the planet’s rotation — because it did not form alongside Neptune. Astronomers believe Triton was an independent Kuiper Belt object, similar to Pluto, that was captured by Neptune’s gravity long ago. Its backward, tilted orbit is the clearest evidence of this dramatic capture event.

The Sun is the star at the heart of our solar system — a 4.6-billion-year-old sphere of incandescent plasma whose gravity holds every planet, moon, asteroid and comet in orbit, and whose light makes life on Earth possible. As an astrophotographer who has chased the night sky since 2008 and who now runs a remote imaging rig at Deepsky Chile, I spend most of my time photographing faint deep-sky objects after dark. But the one object I always tell beginners to respect more than any other is the daytime star: the Sun. It is the most rewarding target in the sky and, handled carelessly, the most dangerous.

This guide covers everything you actually need to know — the Sun’s internal structure, sunspots and the roughly 11-year solar cycle (we are right at the maximum of Solar Cycle 25 in 2026), solar eclipses, and, above all, how to observe and photograph the Sun without destroying your eyesight or your gear.

Why is safe solar observing the first thing you must learn?

Before a single fact about the Sun, the safety rule comes first because the consequences are immediate and irreversible. Never look at the Sun through a telescope, binoculars, finderscope, or camera viewfinder that does not have a certified solar filter fitted over the front (the aperture end). A telescope concentrates sunlight to a focus that can burn paper and melt plastic; aimed at your retina, it causes painless, permanent blindness in a fraction of a second. There are no pain receptors in the retina, so you will not feel the damage happening.

I cannot overstate this. In nearly two decades in this hobby, the only injuries I have heard of among astronomers came from solar mistakes — a forgotten finderscope cap, a child swinging an unfiltered scope toward the Sun, a cheap eyepiece “sun filter” that cracked under heat. Treat the Sun as the one target that punishes a single lapse.

The three safe ways to observe the Sun

• White-light solar filter: a certified glass or film filter (such as Baader AstroSolar film, ISO 12312-2 compliant) mounted securely over the front aperture of your telescope or binoculars. It blocks more than 99.99% of incoming light. Never use an eyepiece-end “sun filter” — heat builds up at that focus and they shatter.
• Dedicated solar telescope: a purpose-built Hydrogen-alpha (Hα) scope (for example, a Coronado or Lunt) with built-in safe filtration designed only for the Sun.
• Projection: project the Sun’s image through a small refractor or pinhole onto a white card. You never look through the optic — you look at the projected image on the card.

What does NOT work

• Sunglasses, smoked glass, exposed photographic film, CDs, Mylar food wrap, or stacking multiple pairs of eclipse glasses.
• Eyepiece-mounted solar filters (the dangerous old design).
• Welder’s glass below shade 14 (only shade 14 is safe for naked-eye glances, and never through optics).
• Pointing any unfiltered camera, phone, or DSLR through a telescope at the Sun — the sensor and your eye are both at risk.

Always cap or remove your finderscope before solar sessions, and supervise children constantly. For eclipse viewing, use only ISO 12312-2 certified eclipse glasses, and inspect them for scratches first. NASA maintains a clear, authoritative safety page worth reading before your first session at NASA’s Sun science portal.

What is the Sun, exactly?

The Sun is a G-type main-sequence star (a “yellow dwarf,” though it actually appears white from space). It accounts for about 99.8% of all the mass in the solar system — everything else, every planet and moon combined, is rounding error by comparison. It is an enormous ball of hot plasma held together by its own gravity and powered by nuclear fusion in its core.

The Sun formed roughly 4.6 billion years ago from the gravitational collapse of part of a giant molecular cloud. It is a little under halfway through its main-sequence lifetime and will continue fusing hydrogen for another 5 billion years or so before swelling into a red giant and finally settling down as a white dwarf.

Key Sun facts at a glance

That last point — differential rotation — is one reason the Sun has such a complex, ever-changing magnetic field, which in turn drives sunspots and the solar cycle we’ll come to shortly.

What are the layers of the Sun?

The Sun has no solid surface. Instead it is organized into distinct layers, from the fusion furnace at its center out to the wispy corona that stretches millions of kilometers into space. Energy generated in the core takes an astonishingly long time — tens of thousands of years — to fight its way out to the surface.

The interior: core, radiative zone, convective zone

• Core: The central ~25% of the Sun’s radius, where temperatures hit ~15 million °C and pressure is crushing. Here hydrogen nuclei fuse into helium, converting mass into energy via the proton-proton chain. This is the engine that powers the entire star.
• Radiative zone: Surrounding the core, energy travels outward as photons that are absorbed and re-emitted countless times. A single packet of energy can take tens of thousands of years to cross this region.
• Convective zone: In the outer third, plasma physically boils — hot material rises, cools, and sinks in giant convection cells. This churning is visible at the surface as a granular, bubbling texture.

The atmosphere: photosphere, chromosphere, corona

• Photosphere: The visible “surface,” about 5,500 °C, where sunlight escapes into space. This is where you see sunspots and granulation through a white-light filter.
• Chromosphere: A thin reddish layer above the photosphere, best seen in Hydrogen-alpha light, where prominences and filaments live.
• Corona: The Sun’s outer atmosphere, mysteriously hotter than the surface — up to 2 million °C — and visible to the naked eye only during a total solar eclipse, when the Moon blocks the photosphere’s glare. The European Space Agency’s solar missions, described at ESA’s Solar Orbiter pages, are dedicated to understanding why the corona is so hot.

To put the layers in context with the other bodies the Sun governs, it helps to step back and see the whole system — our guide to the solar system maps how the Sun’s gravity shapes everything that orbits it.

What are sunspots and how do they form?

Sunspots are the single most rewarding feature to observe in white light, and they are the visible fingerprints of the Sun’s magnetism. A sunspot is a region of the photosphere where intense magnetic fields suppress the convection that normally carries heat upward. Because less heat reaches the surface there, the region is cooler — around 3,500 °C versus the surrounding 5,500 °C — so it looks dark by contrast. In reality a sunspot is blindingly bright; it only appears dark against the hotter background.

Sunspots often appear in groups and can be larger than Earth. They have two parts: the dark central umbra and the lighter, filamentary penumbra around it. Through my refractor with a white-light filter, even a modest sunspot group shows this structure beautifully, and tracking the same group day to day as it rotates across the disk is one of the most satisfying projects in amateur astronomy.

What causes them

The Sun’s differential rotation — faster at the equator than the poles — winds up and tangles its internal magnetic field over years. Where bundles of magnetic field lines pierce the surface, they choke off convection and create sunspots. The number of sunspots rises and falls in a roughly 11-year rhythm, which brings us to the solar cycle.

What is the solar cycle, and where are we in 2026?

The solar cycle is the roughly 11-year rise and fall in the Sun’s magnetic activity, measured most simply by counting sunspots. At solar minimum the disk can go days without a single spot; at solar maximum it can be peppered with large active regions, and flares and coronal mass ejections become frequent. At the end of each cycle the Sun’s magnetic field flips polarity entirely.

We are currently in Solar Cycle 25. NASA and NOAA announced in October 2024 that the Sun had entered its solar maximum period, and this cycle has been notably stronger than originally forecast — sunspot counts reached a 23-year high, and the Sun unleashed an X9.0 flare, its most powerful of the cycle, on 3 October 2024. Through 2025 and into 2026 we remain near the peak, with the declining phase expected to set in gradually thereafter.

What this means for you in 2026: this is one of the best times in a decade to observe and photograph the Sun. Sunspots are plentiful, prominences leap off the limb, and aurora-producing geomagnetic storms are frequent. If you have ever wanted to start solar imaging, do it now while activity is high — the next maximum won’t arrive until the mid-2030s. For activity forecasts I check NOAA’s Space Weather Prediction Center, and you can read the cycle background at Britannica’s solar cycle entry.

What happens during a solar eclipse?

A solar eclipse occurs when the Moon passes directly between the Earth and the Sun, casting its shadow on our planet. By a remarkable cosmic coincidence, the Moon and the Sun appear almost exactly the same size in our sky, which makes total solar eclipses possible.

• Total eclipse: The Moon completely covers the photosphere, revealing the ghostly corona. For the brief minutes of totality — and only during totality — it is safe to look with the naked eye.
• Partial eclipse: The Moon covers only part of the disk. You must use eclipse glasses or filtered optics the entire time.
• Annular eclipse: The Moon is near apogee and appears slightly too small to cover the Sun, leaving a bright “ring of fire.” This is never safe to view without protection.

The single most common eclipse injury comes from people removing eclipse glasses a few seconds too early or too late around totality. If you are not certain you are in the path of totality, keep your filters on the entire time. To understand the geometry of these alignments, our overview of the Moon and its phases explains why the Moon’s orbit makes eclipses both possible and rare.

How do you photograph the Sun safely?

Solar imaging splits into two distinct disciplines, and they produce completely different photographs. I’ve done both, and they each have their own learning curve and gear.

White-light imaging

This captures the photosphere — sunspots and granulation. You fit a certified white-light filter (glass or Baader AstroSolar film) over the front of any telescope, then attach a camera. Key tips from my own sessions:

• Use a high-frame-rate planetary camera and shoot short video clips, then stack the sharpest frames (lucky imaging) to beat atmospheric turbulence.
• Image when the Sun is high in the sky to minimize the thick, turbulent air near the horizon.
• Keep exposures short — the filter cuts the light, but the Sun is still extremely bright.
• Double-check the filter is seated and undamaged before the scope ever points sunward.

Hydrogen-alpha (Hα) imaging

This requires a dedicated Hα solar telescope, which isolates a single deep-red wavelength emitted by the chromosphere. The reward is dramatic: writhing prominences arcing off the limb, dark filaments snaking across the disk, and bright active regions around sunspots. Hα scopes are more expensive and have a tuning “etalon” you adjust for contrast, but nothing in white light compares to a big prominence in Hα.

Whichever path you take, the framing and focal-length choices matter. The Sun is about half a degree across, the same as the full Moon, so before buying a camera-and-scope combination it is worth running the numbers through our telescope field-of-view calculator to confirm the full disk will fit your sensor at your chosen focal length.

How does the Sun compare to other stars and to the planets?

By the standards of the galaxy the Sun is fairly ordinary — a middle-aged, middle-sized star. There are stars far larger and far smaller, far hotter and far cooler. But it is exactly stable and long-lived enough to have given life on Earth billions of uninterrupted years, which is anything but ordinary for the beings who depend on it.

Its gravity defines the entire neighborhood. The innermost world, scorched Mercury, races around it in just 88 days, while distant ice giants take well over a century. The Sun is the reference point for everything else — if you want the broader tour, our planets guide walks through each world the Sun holds in orbit, and our meteor showers calendar covers the cometary debris that the Sun’s heat sheds into glowing trails in our skies.

Practical tips for your first solar session

If you’re setting up to observe the Sun for the first time, here is the workflow I follow every time, refined over years of sessions:

1. Cap or remove the finderscope before you go outside. This is the most common cause of accidents.
2. Fit the certified front filter and check it is secure and unscratched. Tape it if there’s any wobble.
3. Aim using the scope’s shadow — never sight along the tube. Minimize the tube’s shadow on the ground to center the Sun.
4. Start at low magnification, find the disk, then zoom in on sunspot groups.
5. Observe in short sessions and keep bystanders, especially children, supervised at all times.

Do all of that and the Sun becomes the most accessible serious target in astronomy — it’s up in daylight, it changes day to day, and during the Cycle 25 maximum of 2026 it is putting on a genuine show.

Frequently asked questions

Is it ever safe to look at the Sun through a telescope?

Only with a certified solar filter fitted over the front aperture, a dedicated solar telescope, or by projecting the image onto a card. Never look through any unfiltered telescope, binoculars, finder, or camera at the Sun — even for an instant. The focused light causes painless, permanent retinal burns and blindness with no warning.

How big and how hot is the Sun?

The Sun is about 1.4 million kilometers (865,000 miles) across — roughly 109 Earths wide — with a mass around 333,000 times Earth’s. Its visible surface is about 5,500 °C, its core reaches roughly 15 million °C, and its outer corona is hotter still at up to 2 million °C.

What is the solar cycle and are we at maximum in 2026?

The solar cycle is the roughly 11-year rise and fall in the Sun’s magnetic activity, tracked by sunspot numbers. NASA and NOAA confirmed the Sun reached the maximum of Solar Cycle 25 in October 2024, and through 2025–2026 we remain near that peak, making it an excellent time to observe sunspots, prominences, and aurorae.

Why do sunspots look dark?

Sunspots are regions where strong magnetic fields block the convection that carries heat to the surface, so they are cooler — about 3,500 °C versus the surrounding 5,500 °C. They appear dark only by contrast; in absolute terms a sunspot is still extremely bright.

What’s the difference between white-light and Hydrogen-alpha solar imaging?

White-light imaging uses a front-aperture filter to show the photosphere — sunspots and surface granulation. Hydrogen-alpha imaging uses a dedicated solar scope tuned to a single red wavelength to reveal the chromosphere, including prominences and filaments. Both are safe when done with proper certified equipment; they simply show different layers of the Sun.