The Solar System: A Complete Guide to Everything Orbiting the Sun

By Hamza — astrophotographer since 2008, imaging from a remote rig (Alluna 12.5″ Ritchey-Chrétien, Paramount MX+, SBIG STL-11000) at Deepsky Chile.

Quick answer: The solar system is the Sun and everything bound to it by gravity — 8 planets, 5 officially recognized dwarf planets, more than 400 planetary moons (890+ counting moons of dwarf planets, asteroids and TNOs), more than 1.4 million tracked asteroids, and about 4,600 known comets. It formed 4.6 billion years ago, and the Sun holds 99.86% of all its mass.

The solar system is our cosmic neighborhood: one ordinary star and the vast swarm of worlds, rocks, ice, and dust held captive by its gravity. It stretches from the scorched rock of Mercury, closest to the Sun, out past Neptune to the frozen Kuiper Belt and the distant Oort Cloud — a shell of comets so far away that the Sun looks like just another star. Everything you can see with the naked eye on a clear night, plus billions of objects you cannot, belongs to this single gravitational family that took shape 4.6 billion years ago from a collapsing cloud of gas and dust.

A quick note on those counts, because they grow every month. Of the 1.4-million-plus minor planets astronomers have tracked, roughly 895,000 are formally numbered, and the rest await enough observations to lock down their orbits. The five dwarf planets — Ceres, Pluto, Haumea, Makemake, and Eris — are the only ones the International Astronomical Union has officially blessed, though dozens more candidates are waiting in the wings. Moon counts have exploded too, especially around Saturn and Jupiter, as deep surveys reveal tiny new satellites.

This guide is different from the generic science pages. It is a complete pillar covering the Sun, all eight planets, the dwarf planets, and the small bodies — asteroids, comets, and trans-Neptunian objects — alongside something the encyclopedias leave out: how to actually see and photograph each of these worlds from your own backyard. For every object class below you will find an observing-difficulty note — naked-eye, binocular, telescope, or imaging-only — drawn from real nights under the sky, including my own from the southern hemisphere. Think of this page as the hub: each section gives you the essentials, then links down to a deep-dive when you want to go further.

Table of contents

1. What is the solar system?
2. How the solar system formed
3. The solar system in the Milky Way
4. Objects in the solar system: the master comparison table
5. The Sun: our star
6. The eight planets
7. Dwarf planets
8. Small solar system bodies: asteroids, comets, Centaurs and TNOs
9. Asteroids
10. Comets
11. Trans-Neptunian objects: the Kuiper Belt & Oort Cloud
12. Is there a Planet Nine?
13. Moons
14. Meteors and meteor showers
15. Where does the solar system end?
16. The state of solar-system exploration (2026)
17. How to observe and photograph the solar system
18. Best targets for beginners
19. Solar system records and fun facts
20. Frequently asked questions

What is the solar system?

The solar system is the Sun and everything held in orbit around it by gravity. That includes the eight planets in order from the Sun, five recognized dwarf planets, more than 400 planetary moons (890+ counting moons of dwarf planets, asteroids and TNOs), and millions of smaller bodies like asteroids, comets, and distant trans-Neptunian objects.

At the center sits one star. The Sun is so dominant that nothing else comes close to rivaling it.

The Sun runs everything

The Sun holds about 99.86% of all the mass in the solar system. Jupiter and Saturn make up most of the leftover sliver, and every other planet, moon, and rock shares the tiny remainder.

That overwhelming mass is why the Sun governs the orbits. Gravity scales with mass, so the Sun’s pull sets the path of every planet and comet, even ones that take thousands of years to loop around it. The whole system is, quite literally, a collection of objects falling endlessly around a single star.

Measuring the distances: the astronomical unit

Distances out here are too large for kilometers to feel meaningful, so astronomers use the astronomical unit (AU). One AU is the average distance from Earth to the Sun, about 150 million km (93 million miles).

A clearer way to picture an AU is by light-travel time. Sunlight takes roughly 8 minutes and 20 seconds to reach Earth, so 1 AU is “8 light-minutes” away. Use that ruler and the scale of the system snaps into focus:

Object	Distance from Sun	Sunlight travel time
Mercury	0.39 AU (58 million km / 36 million mi)	~3.2 minutes
Earth	1 AU (150 million km / 93 million mi)	~8.3 minutes
Jupiter	5.2 AU (778 million km / 484 million mi)	~43 minutes
Neptune	30 AU (4.5 billion km / 2.8 billion mi)	~4.1 hours
Voyager 1 (2026)	~172 AU (25.7 billion km / 16 billion mi)	~24 hours (one light-day)

The light that lets you see Jupiter through a telescope left the Sun nearly an hour ago. When you observe the outer planets, you are always looking slightly into the past.

Why the solar system is flat

The planets do not orbit at random angles. They travel in nearly the same plane, like marbles rolling on a tabletop. That plane is called the ecliptic.

This flatness is a fingerprint of how the system formed. It condensed from a spinning cloud of gas and dust that flattened into a disk, and the planets grew from that disk, inheriting its plane.

For observers, the ecliptic is the single most useful line in the sky. The Sun, Moon, and every planet ride along it, tracing the same arc the Sun follows by day. So if you want to find Mars, Jupiter, or Saturn at night, you scan that band, not the whole sky. From my own imaging runs at Deepsky Chile, planning a session always starts with where the ecliptic sits, because that is where the planets and the Moon will be.

How the solar system formed

The solar system formed about 4.6 billion years ago when a giant cloud of gas and dust collapsed under its own gravity, flattened into a spinning disk, and built the Sun and planets from the leftovers. This is the nebular hypothesis, and it remains the best-supported model of our origins.

It starts with a molecular cloud — a cold, dark stretch of mostly hydrogen and helium seeded with heavier elements from earlier dead stars. A nearby shockwave, perhaps from an exploding star, nudged part of this cloud into collapse. As the material fell inward, it spun faster and flattened into a protoplanetary disk, much like pizza dough stretched by a spinning cook.

Most of the matter piled into the dense, hot center. When that core grew massive and hot enough, nuclear fusion ignited and the Sun switched on — claiming over 99.8% of the system’s mass. The young Sun’s heat and wind then carved the rest of the disk into the layout we see today.

That layout was set by the frost line (also called the snow line), the distance from the Sun — roughly 2.7 astronomical units, out in today’s asteroid belt — beyond which it was cold enough for water, ammonia, and methane to freeze into ice:

• Inside the frost line only metals and rock could stay solid, so the inner zone built small, dense, rocky worlds — Mercury, Venus, Earth, and Mars. Explore each of them in the planets of the solar system sub-hub.
• Beyond the frost line ice was abundant, so growing cores swept up huge amounts of solid material plus gas, becoming the giants — Jupiter, Saturn, Uranus, and Neptune.

Planets grew by accretion: dust grains stuck together into pebbles, pebbles into boulders, and boulders into planet-sized bodies called planetesimals that swept their orbits clean.

The leftovers never finished. Rubble that Jupiter’s gravity kept from forming a planet became the asteroid belt, while icy crumbs in the cold outer reaches became the comets and the distant worlds of the Kuiper Belt and beyond.

How do we know the age? We date it from the oldest meteorites — primitive chunks of that original disk that fell to Earth. Radiometric dating of these “calcium-aluminium-rich inclusions” gives a remarkably consistent 4.567 billion years, pinning the moment our solar system began. For more on the collapsing-cloud model, see NASA’s overview of how the solar system formed.

The solar system in the Milky Way

The solar system is not floating in empty space — it rides inside a much larger structure, the Milky Way galaxy, and it is constantly on the move. Knowing where our neighborhood sits in the galaxy puts every distance on this page into a humbling new perspective.

We live in a quiet suburb of the galaxy called the Orion Arm (also known as the Orion Spur or Local Arm), a minor spiral feature between two of the galaxy’s major arms, the Sagittarius Arm and the Perseus Arm. It is a good address for life: far from the crowded, radiation-soaked galactic core, in a calm stretch of the disk.

The Sun and its whole family of planets sit roughly 26,000 light-years from the center of the Milky Way, a little more than halfway out from the core to the visible edge of the galactic disk. The center itself hosts a supermassive black hole, Sagittarius A*, about four million times the mass of the Sun.

And we are not standing still. The entire solar system orbits the galactic center at a staggering roughly 828,000 km/h (about 514,000 mph). Even at that blistering speed, the galaxy is so enormous that one full lap — known as a galactic year — takes about 230 million years. The last time the Sun was in its current galactic position, dinosaurs had not yet appeared on Earth.

For an observer, the Milky Way is the faint, glowing band that arches across a truly dark sky. When you look toward the densest part of that band — in the direction of the constellation Sagittarius — you are looking straight toward the galactic core, through tens of thousands of light-years of stars, gas, and dust. From my dark-sky site in Chile, that core region rides high overhead in the southern winter, and it is one of the great rewards of imaging from the southern hemisphere.

Objects in the solar system: the master comparison table

The solar system is arranged in a clear sequence outward from the Sun. The four small, rocky inner planets come first, then the asteroid belt, then the four giant outer planets, and finally a vast frontier of icy bodies that stretches almost a quarter of the way to the nearest star.

Here is the order from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. The asteroid belt sits between Mars and Jupiter, marking the boundary between the inner and outer solar system.

The table below is the single master reference for this whole guide. It gathers every major object class — the Sun, the eight planets, the five dwarf planets, and the small-body regions — into one place, with distance, size, orbital period, day length, moon count, temperature, and how hard each is to observe from the ground.

Object	Type	Distance (AU + million km/mi)	Diameter (km / mi)	Orbital period	Day length	# Moons	Mean temperature	Observing difficulty
Sun	Star (G2V)	0	1,392,700 / 865,000	—	~25 Earth days (equator)	—	5,500 °C surface (9,900 °F)	Naked-eye with certified filter only; telescope with white-light or H-alpha filter
Mercury	Terrestrial planet	0.39 (58 / 36)	4,879 / 3,032	88 days	59 days	0	167 °C (333 °F)	Naked-eye low in twilight near greatest elongation
Venus	Terrestrial planet	0.72 (108 / 67)	12,104 / 7,521	225 days	243 days	0	465 °C (870 °F)	Naked-eye (brightest planet); telescope shows phases
Earth	Terrestrial planet	1.00 (150 / 93)	12,742 / 7,918	365 days	24 hours	1	15 °C (59 °F)	Home — naked-eye
Mars	Terrestrial planet	1.52 (228 / 142)	6,779 / 4,212	687 days	24.6 hours	2	−65 °C (−85 °F)	Naked-eye; telescope at opposition for surface detail
Asteroid belt	Small-body region	2.2–3.2 (330–480 / 205–300)	varies	3–6 years	varies	—	−73 °C (−100 °F)	Binoculars (Vesta/Ceres at opposition) to telescope
Jupiter	Gas giant	5.20 (778 / 484)	139,820 / 86,881	11.9 years	9.9 hours	95+	−110 °C (−166 °F)	Naked-eye; binoculars show Galilean moons
Saturn	Gas giant	9.58 (1,434 / 891)	116,460 / 72,367	29.4 years	10.7 hours	274+	−140 °C (−220 °F)	Naked-eye; small telescope shows rings
Uranus	Ice giant	19.20 (2,871 / 1,784)	50,724 / 31,518	84 years	17.2 hours	28	−195 °C (−320 °F)	Binoculars/telescope; tiny blue-green disk
Neptune	Ice giant	30.05 (4,495 / 2,793)	49,244 / 30,599	165 years	16.1 hours	16	−200 °C (−330 °F)	Telescope/imaging only; far too faint for the eye
Ceres	Dwarf planet	2.77 (414 / 257)	940 / 584	4.6 years	9 hours	0	−105 °C (−157 °F)	Binoculars at opposition (~mag 7)
Pluto	Dwarf planet	39.5 (5,900 / 3,670)	2,377 / 1,477	248 years	6.4 days	5	−229 °C (−380 °F)	Imaging-only; ~mag 14, needs 8-inch scope
Haumea	Dwarf planet	43.2 (6,450 / 4,010)	~2,100 / 1,300 (long axis)	285 years	3.9 hours	2	−241 °C (−402 °F)	Imaging-only (~mag 17)
Makemake	Dwarf planet	45.4 (6,800 / 4,220)	1,430 / 888	306 years	22.5 hours	1	−239 °C (−398 °F)	Imaging-only (~mag 17)
Eris	Dwarf planet	67.8 (10,100 / 6,300)	2,326 / 1,445	558 years	25.9 hours	1	−243 °C (−405 °F)	Imaging-only (~mag 19)
Kuiper Belt	Icy-body region	30–50 (4,500–7,500 / 2,800–4,700)	varies	200–450 years	varies	—	−230 °C (−380 °F)	Imaging-only
Oort Cloud	Comet shell	~2,000–100,000 (up to ~15 trillion km)	varies	thousands–millions of years	—	—	near −270 °C (−454 °F)	Never directly observed

A quick way to memorize the eight planets in order is the classic mnemonic: My Very Educated Mother Just Served Us Nachos — the first letter of each word matches a planet (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune). Older versions ended in “Nine Pizzas” for Pluto, but Pluto’s 2006 reclassification as a dwarf planet dropped it from the list.

One AU (astronomical unit) equals the average Earth–Sun distance, about 150 million km (93 million miles), so the scale jumps fast: Neptune orbits 30 times farther from the Sun than Earth does, and the Oort Cloud may reach 100,000 AU. For a deeper look at each world, including observing tips and the best times to view them, see our complete guide to the planets.

The Sun: our star

The Sun is the star at the heart of our solar system, and everything else orbits it. It is a G2V yellow dwarf, a middle-aged, middle-sized star roughly 4.6 billion years old. Despite “dwarf” in the name, it is enormous: about 1.39 million km (865,000 mi) across, wide enough to line up 109 Earths edge to edge.

Its gravity is the glue that holds the whole neighborhood together. The Sun packs roughly 99.86% of all the mass in the solar system, leaving every planet, moon, asteroid, and comet to share the last fraction of a percent. Learn more about its structure and life cycle on our dedicated guide to the Sun.

Powered by fusion. Deep in the core, where temperatures top 15 million °C (27 million °F), hydrogen fuses into helium. The Sun converts about 600 million tonnes of hydrogen every second, turning roughly 4 million tonnes of that into pure energy. That energy takes tens of thousands of years to claw its way to the surface, then just 8 minutes and 20 seconds to cross 150 million km (93 million mi) and reach your eyes.

Property	Value
Spectral type	G2V (yellow dwarf)
Diameter	~1.39 million km (865,000 mi)
Share of solar system mass	~99.86%
Core temperature	~15 million °C (27 million °F)
Surface (photosphere)	~5,500 °C (9,900 °F)
Corona temperature	1–3 million °C (1.8–5.4 million °F)
Activity cycle	~11 years
Age	~4.6 billion years

A layered, restless star. The visible “surface” is the photosphere, a churning layer at about 5,500 °C (9,900 °F). Above it lies the corona, the faint outer atmosphere that paradoxically blazes to 1–3 million °C (1.8–5.4 million °F) and only becomes visible to the naked eye during a total solar eclipse. The photosphere is freckled with sunspots, cooler magnetic regions (around 3,500–4,000 °C / 6,300–7,200 °F) that come and go on an 11-year activity cycle. When the Sun’s twisted magnetic field snaps, it unleashes solar flares and coronal mass ejections, hurling charged particles outward. Those particles spark the auroras (northern and southern lights) when they slam into Earth’s magnetic field.

The only star you can image in surface detail. Every other star is a single point of light, even in the largest telescopes. The Sun is the lone exception: from your own backyard you can resolve sunspots, granulation, and, with the right gear, flaming prominences arcing off the edge. It is the most rewarding target in all of astrophotography for sheer detail.

SAFETY — read this first. NEVER look at the Sun through any telescope, binoculars, or camera without a purpose-made solar filter, and NEVER point unfiltered optics at it. Focused sunlight will cause instant, permanent blindness and can melt your equipment in seconds. Use only a certified full-aperture white-light solar filter (fitted over the front of the scope) or a dedicated hydrogen-alpha solar telescope. “Solar eclipse glasses” are for naked-eye use only, NOT for use with optics. When in doubt, do not look.

Observing difficulty: naked-eye with a certified solar filter only; binoculars or a telescope only with a full-aperture white-light filter or a dedicated hydrogen-alpha scope. A white-light filter reveals sunspots and the granular photosphere, while a hydrogen-alpha scope adds prominences and surface filaments. Best time: any clear day, with steadiest air usually in the morning. Minimum aperture: any size works — even a 60 mm scope shows sunspots safely with the right filter. The Sun is the one deep-space target that is best in broad daylight, making it perfect for observers who can’t stay up late.

The eight planets

Eight planets orbit the Sun. In order from the Sun, they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Each one is a world unto itself, and several are bright, rewarding targets for backyard telescopes.

So what officially counts as a planet? In 2006, the International Astronomical Union (IAU) settled the question with a three-part test. To be a planet, a body must:

1. Orbit the Sun — not another planet (which would make it a moon).
2. Be massive enough to be round — its own gravity pulls it into a near-spherical shape (a state called hydrostatic equilibrium).
3. Have cleared its orbital neighborhood — it gravitationally dominates its lane around the Sun, sweeping up or flinging away other debris.

That third rule is the one that demoted Pluto. Pluto is round and orbits the Sun, but it shares its zone with countless icy bodies in the Kuiper Belt, so it became a dwarf planet instead. For the full roster and the science of these worlds, see the dedicated guide to the planets.

Two planet families

The eight planets split cleanly into two groups, separated by the asteroid belt.

• Terrestrial (rocky) planets — Mercury, Venus, Earth, and Mars. Small, dense, rocky worlds with solid surfaces you could (in principle) stand on. These are the four inner planets.
• Giant planets — Jupiter, Saturn, Uranus, and Neptune. Huge, low-density worlds with no solid surface. Astronomers split these further into gas giants (Jupiter and Saturn, dominated by hydrogen and helium) and ice giants (Uranus and Neptune, richer in water, ammonia, and methane “ices”). These are the four outer planets.

A quick tour, world by world

Mercury — the smallest and fastest planet, racing around the Sun every 88 days. It has almost no atmosphere (just a thin exosphere), so its surface swings from about 430 °C (800 °F) in daylight to −180 °C (−290 °F) at night — the widest temperature range of any planet. From a backyard, it never strays far from the Sun, so catch it low in twilight during a “greatest elongation.” Read more about observing the innermost planet, Mercury.

Venus — Earth’s near-twin in size, but a hellish one. A thick carbon-dioxide atmosphere traps heat in a runaway greenhouse effect, baking the surface to about 465 °C (870 °F), hot enough to melt lead. Venus is the brightest planet in our sky and, through a telescope, shows phases like the Moon.

Earth — the only world known to harbor life, and the only one with liquid water oceans on its surface. Its large Moon stabilizes the planet’s tilt — holding our obliquity within a narrow band near 23.4° — which helps keep our climate steady over geological time.

Mars — the rusty “Red Planet,” colored by iron oxide in its soil. It hosts the tallest volcano in the solar system, Olympus Mons, which rises about 22 km (14 mi) above the surrounding plains — roughly two and a half times the height of Mount Everest. Mars is a classic telescope target near opposition, when its polar caps and dark surface markings sharpen into view. Get the full picture in our Mars observing guide.

Jupiter — the king of the planets, more massive than all the others combined (about 2.5 times over). Its Great Red Spot is a storm still wider than Earth that has been tracked through telescopes for nearly two centuries of continuous observation, though it has been steadily shrinking and is now the smallest ever measured. Even a small telescope reveals its cloud bands and the four bright Galilean moons, which shift position from night to night — explore them in our Jupiter guide.

Saturn — the jewel of the solar system, famous for its dazzling ring system made of countless chunks of ice and rock. It’s the least dense planet — so low in density it would float in water if you had a big enough bathtub. It also reigns as the solar system’s moon king, with hundreds of confirmed satellites. The moment those rings snap into focus in an eyepiece is unforgettable; see how in our Saturn guide.

Uranus — the tipped-over ice giant, rotating on its side at a 98° tilt, likely from an ancient giant impact. This means each pole gets about 42 years of continuous sunlight followed by 42 years of darkness. It glows a pale blue-green and appears as a tiny disk in a backyard telescope.

Neptune — the most distant planet, a deep-blue ice giant about 30 times farther from the Sun than Earth. It boasts the fastest winds in the solar system, exceeding 2,000 km/h (1,200 mph). Far too faint for the naked eye, Neptune was the first planet found by mathematical prediction rather than direct observation, in 1846.

Planet	Type	Distance from Sun (AU + million km/mi)	Diameter	Moons
Mercury	Terrestrial	0.39 (58 / 36)	4,879 km (3,032 mi)	0
Venus	Terrestrial	0.72 (108 / 67)	12,104 km (7,521 mi)	0
Earth	Terrestrial	1.00 (150 / 93)	12,742 km (7,918 mi)	1
Mars	Terrestrial	1.52 (228 / 142)	6,779 km (4,212 mi)	2
Jupiter	Gas giant	5.20 (778 / 484)	139,820 km (86,881 mi)	95+
Saturn	Gas giant	9.58 (1,434 / 891)	116,460 km (72,367 mi)	274+
Uranus	Ice giant	19.22 (2,871 / 1,784)	50,724 km (31,518 mi)	28
Neptune	Ice giant	30.05 (4,495 / 2,793)	49,244 km (30,599 mi)	16

Observing difficulty for the eight planets: naked-eye for Mercury, Venus, Mars, Jupiter, and Saturn at the right time of year; binoculars or a small telescope for Uranus (a faint blue-green star at magnitude 5.7); telescope or imaging only for Neptune (magnitude 7.8, never naked-eye). Best time for the outer planets is opposition; Mercury and Venus show best near greatest elongation. Minimum aperture for ring and cloud-band detail is about 60–80 mm.

Moon tallies climb almost every year as deep surveys keep catching faint outer satellites, so the giant-planet counts above reflect the latest 2026 figures. Together, these eight worlds span the full range of planetary possibilities, from scorched rock to frozen gas, and four of them — Mars, Jupiter, Saturn, and Venus — are within easy reach of a modest telescope on any clear night.

Dwarf planets

A dwarf planet is a body that orbits the Sun and is massive enough for its own gravity to pull it into a round (or nearly round) shape, but that has not cleared the neighborhood around its orbit of other debris. That last point is the key difference from a true planet. A dwarf planet shares its orbital zone with asteroids, Kuiper Belt objects, or other rubble it was never big enough to sweep up.

This definition came from the International Astronomical Union (IAU) in August 2006. The same vote famously demoted Pluto from the ninth planet to a dwarf planet, shrinking the official planet count from nine to eight. It remains one of the most debated decisions in modern astronomy, and our deep dive on Pluto’s reclassification and what we lost unpacks the science and the controversy.

The IAU currently recognizes five dwarf planets:

Dwarf planet	Location	Diameter	Discovered	One-line profile
Ceres	Asteroid belt	~940 km (584 mi)	1801	The largest asteroid-belt object and the only dwarf planet in the inner solar system; visited by NASA’s Dawn spacecraft.
Pluto	Kuiper Belt	~2,377 km (1,477 mi)	1930	The famous former ninth planet, with five moons and a heart-shaped nitrogen-ice plain mapped by New Horizons in 2015.
Haumea	Kuiper Belt	~2,100 km (1,300 mi) long	2004	A fast-spinning, egg-shaped world with a thin ring and two small moons; one full rotation takes under four hours.
Makemake	Kuiper Belt	~1,430 km (888 mi)	2005	A reddish, methane-frosted Kuiper Belt object with one known faint moon, nicknamed MK 2.
Eris	Scattered disc	~2,326 km (1,445 mi)	2005	Pluto’s near-twin in size but more massive; its 2005 discovery directly triggered the great “what is a planet?” debate.

Four of the five live in the cold outer solar system beyond Neptune, in the Kuiper Belt and scattered disc. Only Ceres sits closer in, tucked inside the asteroid belt between Mars and Jupiter.

Expect this list to grow. Astronomers estimate that dozens, possibly hundreds, of dwarf planets are still waiting in the outer solar system. Strong candidates such as Gonggong, Quaoar, Sedna, and Orcus already meet the size and shape requirements; the IAU simply has not formally classified them yet. For the full roster of candidates, observing notes, and how these icy worlds connect to the broader population of trans-Neptunian objects beyond Neptune’s orbit, see our complete guide to the solar system’s dwarf planets.

Observing difficulty: imaging-only for nearly all of them. Pluto is the brightest at roughly magnitude 14, faint enough to need an 8-inch (200 mm) or larger telescope under dark skies and patience to track its slow motion against background stars over several nights. Ceres is the easy exception: at opposition it brightens to about magnitude 7, within reach of binoculars. The other three are realistic targets only for long-exposure astrophotography.

Small solar system bodies: asteroids, comets, Centaurs and TNOs

Everything orbiting the Sun that is not a planet, a dwarf planet, or a moon falls into one official catch-all category: the small solar system body (SSSB). The IAU coined this term in 2006, the same year it redefined “planet.” In plain terms, an SSSB is any other object held in solar orbit — too small to have pulled itself round, and never massive enough to clear its lane.

That single definition covers an enormous and varied population: the rocky asteroids of the inner system, the icy comets that blaze tails near the Sun, the Centaurs drifting between the giant planets, the near-Earth objects (NEOs) that cross our path, and most of the trans-Neptunian objects of the deep outer system. The sections that follow walk through each class in turn — first the asteroids, then the comets, then the frozen worlds beyond Neptune.

Asteroids

Asteroids are the rocky and metallic leftovers from the solar system’s birth 4.6 billion years ago. They never gathered into a planet, so today they orbit the Sun as a swarm of irregular, cratered worldlets ranging from pebble-sized rubble to bodies hundreds of kilometers across. Most live in the main asteroid belt between Mars and Jupiter, where Jupiter’s gravity stirred the region too violently for a planet to form.

Despite the “belt” name and crowded movie scenes, the region is mostly empty space. If you melted every main-belt asteroid into one ball, it would be smaller than Earth’s Moon, totaling only about 3% of the Moon’s mass. The largest single object, the dwarf planet Ceres, holds roughly a third of that total mass by itself.

Types of asteroids

Astronomers sort asteroids by what they are made of, which mostly tracks where in the belt they formed:

Type	Composition	Notes
C-type (carbonaceous)	Carbon-rich, clay, water-bearing minerals	~75% of known asteroids; dark and ancient; common in the outer belt
S-type (silicaceous)	Rocky silicates with some nickel-iron	Brighter; dominate the inner belt
M-type (metallic)	Mostly nickel-iron metal	Likely exposed cores of shattered protoplanets
Rubble piles	Loose gravel held by weak gravity	Not solid rock — collision debris re-gathered, like Bennu and Itokawa

Centaurs: the comet-asteroid hybrids

Between the orbits of Jupiter and Neptune drifts a strange in-between population called the Centaurs — icy bodies on unstable, planet-crossing orbits that make them hybrids between asteroids and comets. They are named after the half-human, half-horse creatures of myth because they share traits of both families: rocky like an asteroid, but ice-rich like a comet, and some even grow faint comas when they swing close enough to the Sun.

Centaurs do not last long in astronomical terms. The giant planets’ gravity steadily flings them onto new paths, so they are thought to be former trans-Neptunian objects on their way to becoming short-period comets. The first one discovered, 2060 Chiron (found in 1977), behaves exactly like this — it was first catalogued as an asteroid, then surprised astronomers by sprouting a cometary coma. A handful of Centaurs, including Chariklo, even sport their own thin ring systems.

Trojans and near-Earth asteroids

Not every asteroid lives in the belt. Trojans share a planet’s orbit, parked at stable Lagrange points 60 degrees ahead of and behind it. Jupiter has more than a million Trojans larger than 1 km; NASA’s Lucy mission is touring several through the early 2030s, with its final flyby of the Patroclus-Menoetius binary set for 2033.

Near-Earth asteroids (NEAs), a key subset of the broader near-Earth objects, cross or approach Earth’s orbit, and the ones flagged as potentially hazardous get close enough to matter. Tracking and deflecting them is the job of planetary defense. NASA’s 2022 DART mission proved the concept by deliberately slamming a spacecraft into the moonlet Dimorphos and measurably shortening its orbit by about 32 minutes — the first time humans changed a celestial body’s path on purpose. We cover the threat in depth in our guide to what happens if an asteroid hits Earth.

Famous asteroids

• Apophis — a ~340 m (1,100 ft) stony asteroid that will pass within about 32,000 km (20,000 mi) of Earth’s surface on April 13, 2029, closer than our geostationary satellites. It poses no impact risk, but the naked-eye flyby will be a once-in-a-lifetime observing event for some two billion people across Europe, Africa, and western Asia.
• Bennu — a carbon-rich rubble pile visited by NASA’s OSIRIS-REx, which delivered a sample to Earth in 2023 containing the building blocks of life, including amino acids and all five DNA and RNA nucleobases.
• 16 Psyche — a giant metallic asteroid (~220 km / 140 mi) thought to be a battered planetary core; NASA’s Psyche spacecraft is en route for arrival in 2029.
• Vesta — the second-largest belt object and the brightest asteroid, occasionally visible to the naked eye; NASA’s Dawn mission orbited it in 2011–2012 before moving on to Ceres.

Observing difficulty: binoculars to small telescope. Vesta is the only asteroid that ever reaches naked-eye brightness (around magnitude 5.1 at a favorable opposition). Ceres, Pallas, and Juno are easy binocular targets near opposition, appearing as slow-moving “stars” that shift against the background over a night or two. Best time: each asteroid’s own opposition. Minimum aperture: binoculars for the brightest few, a 4-inch scope for fainter members. To confirm a catch, sketch or photograph the field, then compare an hour later — the dot that moved is your asteroid. For the full taxonomy, orbital maps, and a target list by season, see our complete guide to asteroids.

Comets

Comets are the solar system’s “dirty snowballs” — loose mixes of water ice, frozen gases, dust, and rock left over from the system’s birth 4.6 billion years ago. Most spend their lives frozen and invisible in the cold outer reaches. They only come alive when their orbits carry them close to the Sun. Astronomers have catalogued about 4,600 known comets to date, and the number rises every year as sky surveys deepen.

As a comet nears the Sun, its ice sublimates (turns straight from solid to gas). This releases gas and dust that form a glowing coma — a fuzzy atmosphere around the solid nucleus — and one or more tails.

A key fact worth remembering: a comet’s tails always point away from the Sun, not behind its direction of travel. The solar wind and sunlight push the material outward. So an outbound comet actually travels tail-first. Comets typically grow two tails — a bluish ion (gas) tail and a curved, whitish dust tail.

Where comets come from

Comets fall into two families based on how long they take to orbit the Sun:

Type	Orbital period	Source region	Example
Short-period	Less than 200 years	The Kuiper Belt and scattered disc (beyond Neptune)	Halley’s Comet (~76 years)
Long-period	Hundreds to millions of years	The Oort Cloud (the distant icy shell at the solar system’s edge)	Comet Hale-Bopp (~2,500 years)

Short-period comets loop through the inner solar system on a predictable schedule. Long-period comets dive in from the Oort Cloud on enormous, often one-time orbits, which makes them far harder to forecast.

Famous comets

• Halley’s Comet — the most famous of all, last seen in 1986 and returning at perihelion on 28 July 2061. It is the only short-period comet reliably visible to the naked eye from Earth, and the 2061 pass should be far brighter than 1986 because the comet will be on the same side of the Sun as we are.
• Comet Hale-Bopp — the “Great Comet of 1997,” so bright it stayed visible to the naked eye for a record 18 months (May 1996 to December 1997).
• Comet C/2022 E3 (ZTF) — the “green comet” that made its closest approach to Earth on 1 February 2023, its color caused by glowing diatomic carbon (C₂).
• Comet C/2023 A3 (Tsuchinshan-ATLAS) — a stunning naked-eye comet that wowed observers in October 2024, the brightest comet seen since Hale-Bopp.

A handful of visitors are not even from our solar system. 1I/’Oumuamua (2017) and 2I/Borisov (2019) were the first two confirmed interstellar objects — bodies flung in from other star systems, passing through once and leaving forever. A third, 3I/ATLAS, was confirmed in July 2025, showing that these alien visitors are turning up more often as our sky surveys improve.

Observing and photographing comets

Observing difficulty: unpredictable. A bright “great comet” may shine to the naked eye; most others need binoculars or a telescope. Best time: whenever a comet is near perihelion and well placed in a dark sky. Minimum aperture: none for a great comet, binoculars or a 4-inch scope for the rest. Comets are among the most rewarding — and most unpredictable — astrophotography targets, since a faint speck can brighten dramatically (or fizzle) with little warning. Because comets drift against the fixed stars, imagers track the comet’s motion across many short exposures, then stack on the nucleus to keep it sharp. From the southern hemisphere especially, a fresh discovery can mean racing to catch it over just a few clear nights.

For the full breakdown of comet types, upcoming apparitions, and a step-by-step imaging workflow, see our complete guide to observing and photographing comets.

Trans-Neptunian objects: the Kuiper Belt & Oort Cloud

A trans-Neptunian object (TNO) is any body that orbits the Sun at an average distance greater than Neptune, which sits at 30 astronomical units (AU). One AU is the Earth-Sun distance, about 150 million km (93 million miles). This frozen frontier holds the bulk of the solar system’s leftover building blocks, and astronomers have already cataloged more than 5,000 of them. For the full taxonomy and a deeper look at how these worlds were discovered, see our dedicated guide to trans-Neptunian objects and the icy outer solar system.

These distant worlds fall into three main regions, each farther and fainter than the last.

The Kuiper Belt (30–50 AU)

The Kuiper Belt is a doughnut-shaped ring of icy bodies stretching from Neptune’s orbit out to roughly 50 AU. Think of it as the asteroid belt’s bigger, colder cousin, made of rock and frozen volatiles like water, methane, and ammonia ice rather than mostly rock and metal.

This is where Pluto lives, alongside fellow dwarf planets Haumea and Makemake. The belt and its dynamic outer fringe also feed the short-period comets, the kind that loop back through the inner solar system in under 200 years, such as Comet 67P/Churyumov–Gerasimenko, the icy world visited by ESA’s Rosetta mission. When you read about a bright comet swinging past Earth, this region is often its starting point. (Halley’s Comet, by contrast, is a longer-traveling visitor that traces back to the far more distant Oort Cloud.)

The scattered disk

Just beyond and overlapping the Kuiper Belt lies the scattered disk, a sparse population of objects flung onto stretched, tilted orbits by Neptune’s gravity. Eris, the most massive known dwarf planet, is a scattered-disk object. These bodies can swing out to 100 AU or more before falling back toward the Sun. Most short-period comets are now thought to trace back to this restless region rather than the calmer main belt.

The Oort Cloud

Far beyond everything else lies the Oort Cloud, a vast spherical shell of perhaps trillions of icy bodies thought to surround the entire solar system. Unlike the flat, disk-shaped Kuiper Belt, the Oort Cloud wraps the Sun in all directions. Its inner edge may begin around 2,000 AU, and its outer reaches are estimated to extend to roughly 100,000 AU, on the order of 1.6 light-years, a sizable fraction of the way to the next star (Proxima Centauri lies about 4.2 light-years away).

No one has ever directly observed the Oort Cloud; its existence is inferred from the orbits of long-period comets, which take thousands to millions of years to circle the Sun. It marks the true gravitational edge of the solar system.

Region	Distance from Sun	Shape	Notable residents	Comet type produced
Kuiper Belt	30–50 AU	Flat ring/disk	Pluto, Haumea, Makemake	Short-period (<200 yr)
Scattered disk	~30–100+ AU	Tilted, stretched disk	Eris	Most short-period (Jupiter-family)
Oort Cloud	~2,000–100,000 AU (up to ~1.6 ly)	Spherical shell	Sedna (inner edge)	Long-period & Halley-type (1000s+ yr)

Sedna: a world of the deep

Sedna is one of the strangest objects ever found. This reddish dwarf-planet candidate never comes closer than about 76 AU and swings out to roughly 900 AU on an orbit that takes about 11,400 years to complete. Its extreme path suggests it belongs to a transitional zone between the scattered disk and the inner Oort Cloud, possibly shaped by a passing star early in the solar system’s history.

Observing difficulty: imaging-only. Even Pluto, the brightest, glows at only about magnitude 14 to 15, far too faint for the naked eye or binoculars. Capturing it requires an 8-inch (200 mm) or larger telescope, a sensitive camera, and a series of stacked exposures taken over several nights to reveal its slow drift against the stars. Best time: each object’s opposition, under a truly dark sky. From my own remote rig in Chile, confirming a TNO means blinking images night to night and watching for the single dot that moves. Eris is fainter still at about magnitude 19, and Sedna is fainter again near magnitude 21, both well beyond the reach of most backyard setups.

Is there a Planet Nine?

For more than a decade, astronomers have wondered whether a real ninth planet — a genuine giant, not Pluto — is hiding in the dark far beyond Neptune. The idea is known as Planet Nine, and while it is still unconfirmed, the evidence behind it is intriguing.

The hypothesis grew out of a strange pattern. A handful of the most distant trans-Neptunian objects, including Sedna, have orbits that are oddly clustered — tilted and pointed in the same general direction, as if something massive were herding them. In 2016, researchers proposed that an unseen super-Earth, perhaps five to ten times Earth’s mass, could explain that shepherding if it orbits the Sun somewhere around 400 to 800 AU out — far enough that it would be extraordinarily faint and easy to miss.

So far, no one has found it. Wide-sky surveys have ruled out many possible locations, and some astronomers argue the clustering could be an illusion caused by where we have looked, not by a hidden planet. The new Vera C. Rubin Observatory, which began its deep survey of the southern sky in 2025, is exactly the kind of instrument that could either spot Planet Nine or finally rule it out. Until then, the solar system officially has eight planets — but the door on a ninth is not fully closed.

Moons

Moons are natural satellites that orbit planets, dwarf planets, and even some asteroids. The solar system now holds more than 400 planetary moons (890+ counting moons of dwarf planets, asteroids and TNOs), and the count keeps climbing fast as deep surveys uncover swarms of small ones around the giant planets. They range from giant ocean worlds to lumpy captured rocks just a few kilometers wide.

Saturn alone leapfrogged every other planet in 2025, when the International Astronomical Union recognized a large batch of newly found moons. As of mid-2026 Saturn has roughly 274 known satellites, more than all the other planets combined, while Jupiter sits near 95. Earth, by contrast, has exactly one.

Our Moon shapes the tides, stabilizes our axis, and sets the rhythm of every night sky. We cover our own companion in depth on the dedicated Moon hub, from lunar phases to photographing craters along the terminator.

The most fascinating moons are the active, potentially habitable ones. Several rank among the best places to search for life beyond Earth.

Moon	Parent	Why it matters
Ganymede	Jupiter	The largest moon in the solar system, bigger than the planet Mercury, and the only moon known to generate its own magnetic field.
Titan	Saturn	A thick orange nitrogen atmosphere with lakes and rivers of liquid methane and ethane on its surface, the only other world with stable surface liquid.
Europa	Jupiter	A global subsurface ocean of liquid water beneath an icy crust, holding more than twice as much water as all of Earth’s oceans combined.
Enceladus	Saturn	Geysers vent water-ice plumes from a hidden ocean through “tiger stripe” cracks at its south pole.
Io	Jupiter	The most volcanically active body in the solar system, erupting constantly from tidal heating by Jupiter.
Triton	Neptune	A captured world orbiting backward, with nitrogen geysers and a likely subsurface ocean.

Observing the moons: You do not need professional gear to see worlds beyond our own. Point any pair of binoculars at Jupiter and you will spot up to four tiny points of light strung in a line beside it. These are the Galilean moons (Io, Europa, Ganymede, and Callisto), the same four Galileo first sketched in January 1610.

Watch them across a few nights and they visibly shift position, sometimes ducking behind or in front of the planet. That nightly dance was the observation that helped overturn the idea of an Earth-centered cosmos. Titan is reachable too, glowing as a faint star near Saturn through a small telescope. From my remote rig in Chile, tracking those moons as they swing around the gas giants never gets old.

For a complete tour of every major satellite, including the ice volcanoes of the outer system and which moons you can actually capture with a backyard setup, explore our full guide to the moons of the solar system.

Meteors and meteor showers

A meteor is the streak of light you see when a tiny piece of space debris burns up in Earth’s atmosphere. The terms are easy to mix up, so here is the quick distinction:

Term	What it is	Where it is
Meteoroid	A small rock or dust grain, often no bigger than a grain of sand	In space
Meteor	The glowing trail (“shooting star”) as it burns up	In the atmosphere
Meteorite	A fragment that survives the fall and lands	On the ground

Most meteors come from leftover material shed by comets and asteroids. A few are flecks chipped off the Moon or Mars by ancient impacts.

A meteor shower happens when Earth plows through a trail of dusty debris left behind by a comet (or, in one famous case, an asteroid). Each year our planet crosses the same streams on the same dates, so showers are predictable. The grains slam into the atmosphere at anywhere from about 11 to 72 km/s (25,000–160,000 mph) and flare up, all appearing to radiate from one point in the sky.

Two showers stand out for backyard observers:

• Perseids (peak around August 12–13) — warm summer nights and a zenithal hourly rate near 100 (most observers see 50–80 per hour) from comet 109P/Swift-Tuttle, which circles the Sun about every 133 years.
• Geminids (peak around December 13–14) — the year’s richest display, with a zenithal hourly rate of 120+, from the “rock-comet” asteroid 3200 Phaethon.

Observing difficulty: naked-eye, no gear. Meteor showers are the single best free astronomy event. You need no telescope, no binoculars, and no skill. Best time: after midnight on the peak night, with the radiant high and the Moon out of the sky. Just find a dark sky away from city lights, lie back, let your eyes adapt for 20–30 minutes, and look up. A reclining chair and a warm blanket beat any gadget.

For peak dates, hourly rates, radiant positions, and viewing tips for every major shower throughout the year, see our complete guide to meteor showers.

Where does the solar system end?

There is no single edge. The solar system fades out in stages, and where you draw the line depends on whether you mean the Sun’s wind or the Sun’s gravity.

The two boundaries sit thousands of times apart:

Boundary	Distance	What defines it
Heliopause	~120 AU	Where the solar wind stops and interstellar space begins
Gravitational edge (outer Oort Cloud)	~100,000 AU (~1.6 light-years)	The farthest point the Sun’s gravity still holds objects in orbit

The heliopause is the edge of the heliosphere, the giant bubble the Sun inflates with its charged-particle wind. Out near 120 astronomical units (1 AU = the Earth-Sun distance), that wind finally loses to the gas and plasma drifting between the stars. NASA’s twin Voyager probes crossed it for real: Voyager 1 in August 2012 (at about 121 AU) and Voyager 2 in November 2018 (at about 119 AU), making them the first human-made objects to reach interstellar space. Both are still transmitting from beyond it today.

The gravitational edge lies far, far deeper. Beyond the Kuiper Belt and scattered disc sits the Oort Cloud, a vast spherical shell of icy bodies that stretches out to roughly 100,000 AU, about 1.6 light-years, or more than a third of the way to the next star. This is the true outer limit, the launching ground for long-period comets that fall in toward the Sun over millions of years.

So which is the “end”? By the solar wind, you leave at the heliopause. By gravity, you are not truly free of the Sun until you clear the Oort Cloud, a journey that would take even Voyager tens of thousands of years.

The state of solar-system exploration (2026)

The hero image at the top of this page is the famous Voyager montage — and the spacecraft that took those pictures are still working. More than four decades after launch, our robotic explorers have spread across the solar system and beyond, and 2026 finds several of them at extraordinary milestones.

The Voyagers are in interstellar space. Voyager 1 and Voyager 2, launched in 1977, have both crossed the heliopause and now transmit faint signals from beyond the Sun’s bubble of wind. Voyager 1 is the most distant human-made object ever, around 172 AU from the Sun in 2026 — so far that its radio signal, traveling at the speed of light, takes nearly a full day to reach Earth. Their power is fading, but both are expected to keep sending data on the interstellar environment for a few more years.

New Horizons is deep in the Kuiper Belt. After its history-making flyby of Pluto in 2015 — which gave us the heart-shaped nitrogen-ice plain and the first sharp maps of that world — NASA’s New Horizons probe kept going. In 2019 it flew past the small, two-lobed Kuiper Belt object Arrokoth, the most distant object ever explored up close. It is still cruising outward today, studying the dust and particle environment of the outer system.

JWST is doing solar-system science. The James Webb Space Telescope, best known for peering at the early universe, has also become a powerful tool for studying our own neighborhood. It has imaged the giant planets in fresh detail — capturing Neptune’s faint rings more clearly than anything since Voyager 2, tracking storms and auroras on Jupiter, and probing the atmospheres and small moons of the outer worlds. Webb also studies asteroids, comets, and trans-Neptunian objects, adding a new layer to what the flyby missions began.

Together with active orbiters and sample-return missions, these spacecraft mean the solar system is being explored more intensely now than at any time in history. For the science behind the targets they visit, follow the links throughout this guide — and to learn more about how NASA and ESA frame this work, see NASA’s solar system overview.

How to observe and photograph the solar system

The best part of the solar system is that you can see most of it yourself. You do not need a remote observatory to start. You need clear skies, a little patience, and a sense of where to point.

This is where a hub like NASA or Wikipedia stops and a real observer begins. Below is a tiered roadmap based on how I actually work targets, from a first telescope to my remote rig at Deepsky Chile (an Alluna 12.5″ Ritchey-Chretien on a Paramount MX+ with an SBIG STL-11000). You can read more about that setup and my background on the about page.

Three difficulty tiers

Every solar-system object falls into one of three rough tiers of effort. Start at Tier 1 and work down.

Tier	Gear needed	What you can reach
Tier 1 — Naked eye / any scope	Eyes, binoculars, or a basic telescope	The Moon’s craters, Venus phases, Jupiter and its four bright Galilean moons, Saturn’s rings, bright comets, and meteor showers
Tier 2 — Tracking mount	Motorized mount, planetary camera	Mars surface detail at opposition, “lucky imaging” of the planets, the dance of the Galilean moons night to night
Tier 3 — Advanced imaging	Larger aperture, long focal length, careful processing	Faint asteroids, the tiny disks of Uranus and Neptune, dwarf planets, and tracking Pluto as a moving point of light across several nights

Tier 1 is genuinely easy. Saturn’s rings through even a small telescope are a moment people never forget. Jupiter’s four Galilean moons — the same ones Galileo spotted in 1610 — shift position every single night, so two sketches a few hours apart will show them move. Bright comets and meteor showers need no gear at all, just a dark sky and a reclined chair.

Tier 2 starts when you add tracking. A motorized mount keeps a planet centered while you shoot thousands of frames. Software then stacks the sharpest ones, a technique called lucky imaging that freezes the brief moments of steady air. This is how backyard astronomers pull cloud belts off Jupiter and polar ice off Mars at opposition.

Tier 3 is where the solar system gets quiet and faint. Uranus and Neptune show as small blue-green disks only at high magnification on a steady night; you typically need a 3-to-4-inch scope and 150x or more to resolve them into more than a point. Pluto never resolves at all. At around 14th magnitude it takes roughly an 8-inch telescope under a dark sky, and you confirm it by photographing the same star field across two or three nights and watching one “star” drift. Catching a faint asteroid works the same way. This tier rewards patience over money.

Tools that take the guesswork out

Three free calculators on this site solve the planning problems that trip people up most.

• Field of view simulator — Before you buy or shoot, see exactly how big a target lands on your sensor with your scope. It tells you whether Saturn will be a tiny dot or fill the frame, and whether a comet’s tail will fit. This prevents the most common beginner mistake: the wrong focal length for the target.
• Sub-exposure calculator — For fainter objects and wide-field comet shots, this finds the ideal length for each exposure so you swamp sensor noise without blowing out highlights or wasting clear-sky time.
• Astrophotography calculator hub — The all-in-one home for sampling, exposure, and imaging math when you want every tool in one place.

Practical tips that matter more than gear

A few hard-won habits separate frustrating nights from great ones.

• Light pollution caps the faint stuff. The Moon and bright planets punch through city glow, but comets, asteroids, and Uranus/Neptune need real darkness. Check a light-pollution map and, for the faint targets, plan a trip to a darker site.
• Steady seeing beats raw aperture for planets. A small scope on a calm, stable night will show more Jupiter detail than a giant scope on a turbulent one. “Seeing” — how still the air is — is the limiting factor for planetary work, not how much light you gather.
• Learn the ecliptic. The Sun, Moon, and every planet ride the same arc across the sky, called the ecliptic. Once you know that line, you always know roughly where to look, and you can spot when a planet is well placed for the night.
• Time it right. Outer planets are biggest and brightest at opposition — Mars, for example, reaches opposition only about every 26 months. Mercury and Venus only show well near their greatest elongation from the Sun. A good calendar app or planetarium program tells you when.

Master Tier 1 first. The skills and habits you build on the Moon and the bright planets are exactly the ones you carry down into the faint, rewarding depths of Tier 3.

Best targets for beginners

New to a telescope? Start here. These six targets are bright, easy to find, and deliver a real “wow” on your very first night — no dark sky or fancy gear required. Work down the list in order; each one builds your confidence for the next.

1. The Moon — The best first target, full stop. Even cheap binoculars reveal craters, mountains, and the stark shadow line (the terminator) where sunrise sweeps across the surface. A first-quarter phase shows far more detail than a full Moon, because the side-lighting hits the surface at a shallow angle and throws every crater and ridge into sharp relief — at full Moon the sunlight comes straight down and the view looks flat and washed out. Our complete guide to observing and photographing the Moon walks through phases and the best nights to look.
2. Jupiter — Point any small scope at the brightest “star” in that part of the sky and you will see a tiny disk flanked by up to four bright dots: the Galilean moons (Io, Europa, Ganymede, Callisto), which visibly shift position from night to night. With steady air, the two main cloud belts emerge across the disk. See when and how in our Jupiter observing and imaging guide.
3. Saturn — The target that makes people gasp out loud. Even a modest 60-80 mm telescope at 50x or more resolves the rings as a separate structure circling the planet — the single most memorable view in backyard astronomy. (Note that through 2025-2026 the rings sit nearly edge-on, so they look like a thin line; they open wider again over the following years.) The Saturn sub-hub covers ring tilt and the best apertures.
4. Venus — The dazzling “evening star” (or morning star) shows a tiny disk that runs through phases just like the Moon, from a fat gibbous to a slim crescent as it swings around the Sun. Catch it near greatest elongation, when it sits farthest from the Sun’s glare and shows a crisp half-lit “quarter” face. It is a quick, satisfying win even from a light-polluted balcony.
5. A meteor shower — No equipment needed at all — just your eyes, a reclining chair, and a dark-ish sky. Reliable annual showers like the Perseids (peaking around August 12-13) and Geminids (peaking around December 13-14) can deliver dozens of “shooting stars” per hour from a dark site at their peak. Check dates and viewing tips in our meteor showers guide.
6. A bright comet (when one appears) — Once or twice a decade, on average, a comet bright enough for binoculars or even the naked eye graces our skies, trailing a ghostly tail. They are unpredictable, so watch the news and our comets sub-hub for alerts when the next one swings by.

A quick tip from the field: start with the Moon and planets, which punch through light pollution and even shine from a city backyard. Faint deep-sky objects and comets reward darker skies and patience — but you don’t need either to get hooked tonight.

Every object above has its own dedicated observing section in the linked sub-guides, with specific advice on the best time to look, the minimum aperture you’ll want, and how to start photographing it. Pick one clear night, point your scope, and you’re an observer.

Solar system records and fun facts

Hungry for more cosmic trivia? Dig into our deep dive on the secrets of the solar system.

Our cosmic neighborhood holds some jaw-dropping extremes. Here are the record-holders worth knowing — and for backyard observers, several are visible from your own yard with modest gear.

Record	Holder	The number	Why it stands out
Largest planet	Jupiter	~143,000 km (88,800 mi) wide	About 2.5× the mass of all other planets combined
Hottest planet	Venus	~465 °C (~870 °F)	A runaway greenhouse effect, not its distance from the Sun
Tallest volcano	Olympus Mons (Mars)	~22 km (13.6 mi) high	Nearly 2.5× the height of Mount Everest
Largest moon	Ganymede (Jupiter)	5,268 km (3,273 mi) wide	Bigger than the planet Mercury
Fastest winds	Neptune	over 2,000 km/h (1,200 mph)	The strongest gales of any planet, on the most distant world
Most volcanic body	Io (Jupiter)	400+ active volcanoes	Squeezed and heated by Jupiter’s tides

A few standouts deserve a closer look:

• Hottest, not closest. Venus runs hotter than Mercury despite sitting farther from the Sun. Its thick carbon-dioxide atmosphere traps heat in a runaway greenhouse effect, holding the surface near 465 °C (~870 °F) day and night — hot enough to melt lead.

• A moon bigger than a planet. Ganymede, the largest of Jupiter’s Galilean moons, measures 5,268 km (3,273 mi) across — wider than the planet Mercury. Spot all four Galilean moons with even cheap binoculars on any clear night — they shift position from hour to hour as they circle the giant.

• The mountain that dwarfs Everest. Olympus Mons on Mars rises about 22 km (13.6 mi), roughly 2.5 times taller than Everest, and spreads as wide as France. Low gravity and a stationary crust — Mars has no plate tectonics — let lava stack in one spot for billions of years, building the volcano to such size.

• Io, the pizza moon. Jupiter’s innermost large moon is the most volcanically active world we know, with sulfur plumes erupting hundreds of kilometers high. Tidal flexing from Jupiter’s immense gravity — and tugs from neighboring moons Europa and Ganymede — keeps its interior molten.

• Neptune’s once-around milestone. Discovered in 1846, Neptune takes about 165 Earth years to circle the Sun — so it completed its first full orbit since discovery only in July 2011. Most people alive today will never see it finish another.

From Saturn’s glorious rings to the Sun holding 99.86% of the system’s mass, the solar system never runs short of superlatives.

Frequently asked questions

How many objects are in the solar system?
Astronomers have catalogued more than 1.4 million tracked asteroids, about 4,600 known comets, more than 400 planetary moons (890+ counting moons of dwarf planets, asteroids and TNOs), 8 planets, and 5 official dwarf planets, all orbiting one star. The true count runs into the trillions once you include the icy bodies of the Kuiper Belt and the distant Oort Cloud, most of which we have never seen.

What are small solar system bodies?
“Small solar system body” is the official IAU 2006 catch-all for everything orbiting the Sun that is neither a planet nor a dwarf planet nor a moon. It covers asteroids, comets, Centaurs, near-Earth objects, and most trans-Neptunian objects. Our deep dives on asteroids and the asteroid belt, comets, and trans-Neptunian objects break each class down further.

What is the order of the planets from the Sun?
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, then Neptune. The asteroid belt sits between Mars and Jupiter, with the Kuiper Belt and Oort Cloud beyond Neptune.

How do you remember the order of the planets?
Use the classic mnemonic “My Very Educated Mother Just Served Us Nachos.” The first letter of each word matches a planet in order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Older versions ended in “Nine Pizzas” for Pluto, but Pluto was reclassified as a dwarf planet in 2006 and dropped off the list.

Is there a Planet Nine?
Possibly, but it is unconfirmed. The Planet Nine hypothesis proposes an unseen super-Earth, perhaps five to ten times Earth’s mass, orbiting roughly 400 to 800 AU from the Sun. The idea comes from the strangely clustered orbits of several distant trans-Neptunian objects, which look as though a massive body is herding them. No such planet has been found yet, and new surveys like the Vera C. Rubin Observatory should either spot it or rule it out in the coming years.

Is Pluto part of the solar system?
Yes. Pluto is still very much part of the solar system; it was simply reclassified from planet to dwarf planet by the IAU in 2006. You can read the full story of that demotion on our Pluto sub-hub.

How old is the solar system?
The solar system is about 4.6 billion years old. It formed from the gravitational collapse of a giant molecular cloud, with the Sun and planets taking shape over the following few tens of millions of years.

Where does the solar system end?
There is no single fence. The heliopause, where the Sun’s particle wind meets interstellar space, sits roughly 18 billion km (about 11 billion mi) out, while the Sun’s gravity still holds the Oort Cloud as far as 1.6 light-years away, which many astronomers treat as the true edge.

What is the biggest object in the solar system?
The Sun, by an enormous margin. It holds 99.86% of all the mass in the solar system and could swallow more than 1.3 million Earths. Among the planets, Jupiter is the largest.

Can you see the planets without a telescope?
Yes. Mercury, Venus, Mars, Jupiter, and Saturn are all visible to the naked eye and have been watched since ancient times. Venus and Jupiter are bright enough to spot even from a city, while Uranus and Neptune need binoculars or a telescope.

What is the best planet to photograph for a beginner?
Jupiter and Saturn are the easiest and most rewarding first targets. Both are bright, sit well above the horizon for months around opposition, and reveal cloud bands or rings through a modest 4-6 inch telescope and a simple planetary camera. The field-of-view simulator helps you frame them before you shoot.

How many planets have rings?
All four giant planets have ring systems: Jupiter, Saturn, Uranus, and Neptune. Saturn’s are by far the brightest and the only ones easily seen from a backyard telescope; the other three are faint and dusty.

What is the hottest planet in the solar system?
Venus, not Mercury. A runaway greenhouse atmosphere of thick carbon dioxide traps heat and pushes its surface to about 465 °C (around 870 °F), hot enough to melt lead, even though Mercury sits closer to the Sun.

Which planet has the most moons?
Saturn, with roughly 274 confirmed moons as of mid-2026, well ahead of Jupiter at about 95. Most of these are tiny, irregular chunks of rock and ice only a kilometre or two across, found in recent deep surveys rather than seen through a backyard scope. Explore the whole family on our moons of the solar system hub.

How far is the nearest star?
After the Sun, the nearest star is Proxima Centauri, about 4.2 light-years away, or roughly 40 trillion km (25 trillion mi). Even at the blistering speed of NASA’s Voyager probes, the trip would take more than 70,000 years.

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About the author: Hamza has been an astrophotographer since 2008 and operates a remote imaging observatory at Deepsky Chile, using an Alluna 12.5″ Ritchey-Chrétien telescope on a Paramount MX+ mount with an SBIG STL-11000 camera. He shares his work and the night sky of the southern hemisphere on Instagram @stellar.nomads — read more on the about page.

Ready to start imaging these worlds yourself? Plan your first target with the free field-of-view simulator, dial in your exposures with the sub-exposure calculator, or open the all-in-one astrophotography calculator hub — then pick a clear night and point your scope.