Mars: The Red Planet

Mars is the fourth planet from the Sun and the one backyard astronomers chase hardest, because for a few months around each opposition it swells into a genuine, detail-rich disc through the eyepiece. I have been imaging the planets since 2008, and from my remote rig at Deepsky Chile — an Alluna 12.5″ Ritchey–Chrétien on a Paramount MX+ — the red planet remains the single most rewarding and most frustrating target in the sky. This guide explains what Mars actually is, why it glows orange-red, what you can see on its surface, how its opposition cycle works, and exactly how to observe and photograph it yourself.

What is Mars and why is it called the red planet?

Mars is a small, rocky terrestrial planet a little over half the diameter of Earth. It orbits the Sun every 687 Earth days at an average distance of about 228 million kilometres, roughly 1.5 times Earth’s distance. Despite its forbidding cold — average surface temperatures sit near −60 °C — it is the most Earth-like planet we know, with seasons, polar ice, wind, weather, and a day (a “sol”) of 24 hours and 37 minutes.

The famous colour comes from chemistry, not fire. The Martian regolith is loaded with iron, and over billions of years that iron oxidised — it literally rusted. Fine iron-oxide dust coats the surface and is lifted into the thin atmosphere by wind, giving the whole globe its butterscotch-to-ochre tint. So when ancient skywatchers named it after their gods of war for its blood-red glow, they were unknowingly describing planetary-scale rust.

How big is Mars compared with Earth?

Mars has a diameter of about 6,779 km against Earth’s 12,742 km, so it is roughly 53% as wide and has only about 11% of Earth’s mass. Surface gravity is about 38% of ours — a 100 kg person would weigh the equivalent of 38 kg there. That low gravity, combined with a thin carbon-dioxide atmosphere less than 1% the pressure of Earth’s, helps explain why Martian mountains and canyons grew to sizes that dwarf anything on our planet.

What are the main surface features on Mars?

Mars is a planet of superlatives. It hosts the largest volcano and the largest canyon system in the Solar System, plus bright polar caps that visibly wax and wane with the seasons. Even modest telescopes reveal some of these features when the planet is close.

Olympus Mons — the largest volcano in the Solar System

Olympus Mons is a shield volcano standing about 21.3 km high — roughly two and a half times the height of Mount Everest above sea level — and spreading some 600 km across its base, about the size of France. It grew so enormous because Mars has no shifting tectonic plates; a single hotspot kept erupting in the same place for hundreds of millions of years, piling lava ever higher instead of stringing out a chain of smaller volcanoes the way Earth does with Hawaii.

Valles Marineris — the Grand Canyon of Mars

Valles Marineris is a vast system of canyons stretching more than 4,000 km along the Martian equator, up to 200 km wide and as much as 7 km deep. If transplanted to Earth it would reach from New York to Los Angeles. It is not a river-carved canyon like Arizona’s but a tectonic rift — a colossal crack in the crust — later widened by landslides and erosion. You can read more in NASA’s overview of Valles Marineris.

The polar ice caps

Both Martian poles carry bright caps made of water ice with a seasonal overlay of frozen carbon dioxide (dry ice). They are the easiest surface feature to spot from your backyard: as Martian seasons turn, the cap facing us shrinks in local summer and regrows in winter, a change you can actually track over weeks of observing. For me, catching the brilliant white south polar cap during a favourable opposition is always the first “wow” moment of a Mars apparition.

How many moons does Mars have?

Mars has two tiny moons, Phobos and Deimos, discovered in 1877 by Asaph Hall. Both are small, dark, potato-shaped bodies, most likely captured asteroids or debris from an ancient impact. They are nothing like our own large, round Moon — and they are genuinely difficult targets for amateurs because they hide in the planet’s glare.

Phobos, the larger and inner moon, is only about 22 km across and whips around Mars in just 7.7 hours — faster than Mars rotates — so from the surface it would rise in the west and set in the east twice a day. It orbits so low that it is slowly spiralling inward and will eventually break apart or crash into Mars in tens of millions of years. Deimos is smaller still at about 12.6 km and orbits farther out every 30 hours. NASA keeps a concise reference on the moons of Mars. If you enjoy exotic satellites, you may also like our wider guide to planetary moons.

What is Mars opposition and when is the next one?

Mars opposition is the moment when Earth passes directly between Mars and the Sun, so the red planet sits opposite the Sun in our sky — rising at sunset, riding high at midnight, and setting at dawn. Because we are also at our closest, Mars appears biggest and brightest. This is the window every Mars observer waits for.

Oppositions repeat roughly every 26 months, because Earth has to “lap” the slower-orbiting Mars. The last one was on 16 January 2025, which means Mars is not at opposition in 2026 — through 2026 it is on the far side of its cycle, small and distant. The next opposition falls around 19 February 2027. Mark it: that is when planning, equipment tuning, and clear-sky luck should all come together.

Why are some oppositions better than others?

Mars has a noticeably elliptical orbit, so not all oppositions are equal. When opposition happens near Martian perihelion (its closest point to the Sun), Mars can swell to about 25 arcseconds across, as it did spectacularly in 2003 and 2018. The 2025 and 2027 oppositions are “aphelic” — Mars stays farther away and peaks nearer 14 arcseconds. Smaller, yes, but for northern observers these apparitions place Mars high overhead, which steadies the view and often beats a big-but-low disc boiling in the murk near the horizon.

How do you see Mars with the naked eye?

Learning how to see Mars without any equipment is the easiest first step: it is one of the brightest objects in the night sky near opposition and shines with a steady, distinctly orange-pink light. Unlike a star, it does not twinkle much, and its colour gives it away among the white and blue-white stars around it.

To find it, check where the planet currently sits along the ecliptic — a planetarium app or our Solar System hub will show you which constellation hosts it tonight. During 2026, with Mars far from opposition, expect a modest orange “star” rather than a beacon; save your high expectations for late 2026 into early 2027 as it brightens toward the February 2027 event. Mars observing rewards patience: even naked-eye, tracking how it drifts month to month against the stars is a genuine pleasure.

How do you observe Mars through a telescope?

Mars observing through a telescope is the real prize, but it is demanding because the disc is small. Here is the practical approach I use after years of planetary work.

Aperture, magnification and a Barlow

You can glimpse the polar cap and the largest dark markings in a 4-inch (100 mm) scope, but 6 to 10 inches of aperture transforms the view. Mars rewards high magnification — aim for around 200x to 350x when the air is steady. A good 2x or 2.5x Barlow lens paired with a quality eyepiece is the cleanest way to reach those powers without buying a drawer full of short-focal-length eyepieces. Push too hard, though, and you simply magnify a blurry, boiling blob.

Seeing, timing and patience

Atmospheric “seeing” matters more than aperture for Mars. Observe when the planet is high in the sky, let your scope cool to ambient temperature for 30 to 60 minutes, and wait at the eyepiece — detail snaps into focus during brief moments of calm air. A colour filter helps too: an orange or red filter boosts contrast on dark surface markings, while a blue filter highlights clouds, hazes and the polar caps. Want to confirm what fits in your view? Our telescope field-of-view calculator takes the guesswork out of eyepiece and Barlow combinations.

Watch for dust storms

One uniquely Martian hazard: global dust storms. Every few Martian years, regional storms can balloon into planet-encircling events that erase surface detail for weeks — the great 2018 storm did exactly that during a prime opposition. If your familiar dark markings suddenly fade to a bland orange disc, you may be watching a dust storm unfold in real time. It is frustrating and fascinating in equal measure.

How do you photograph Mars?

Imaging Mars relies on a technique called “lucky imaging.” Instead of one long exposure, you record a high-frame-rate video — thousands of frames over a couple of minutes — then use software to keep only the sharpest frames where the atmosphere briefly steadied, and stack them into one clean image.

My workflow from Deepsky Chile

From my Alluna 12.5″ RC on the Paramount MX+, I run a fast planetary camera at high frame rates through a Barlow to reach an effective focal ratio around f/15 to f/20. I capture short videos in AutoStakkert, stack the best 5–10% of frames, then sharpen with wavelets in RegiStax or AstroSurface, finishing colour balance and detail in PixInsight. The dark Chilean skies and high altitude give steadier seeing than most backyards, but the core method is identical at any aperture.

Beat the rotation and the clock

Because Mars rotates in about 24 hours 37 minutes, surface features visibly move during a long capture. Keep each colour-camera run under roughly three to four minutes to avoid smearing detail, or use de-rotation software to combine longer sequences. To plan exposure and signal targets across different setups, I lean on our astrophotography calculator. If planetary imaging hooks you, the same lucky-imaging discipline applies to Jupiter and Saturn — Mars is simply the most unforgiving of the three.

What missions and rovers have explored Mars?

Mars is the most explored planet beyond Earth. Decades of orbiters, landers and rovers have mapped it in extraordinary detail and are actively searching for signs that it was once habitable.

NASA’s Curiosity rover has been climbing Mount Sharp inside Gale Crater since 2012, while the Perseverance rover, which landed in Jezero Crater in 2021, is collecting rock cores for an eventual sample-return mission and flew the first powered aircraft on another world, the Ingenuity helicopter. Orbiters from NASA, ESA, India, the UAE and China continue to study the atmosphere, ice and geology from above. For an authoritative, regularly updated overview, NASA’s Mars exploration program is the best starting point. To put Mars in context with its neighbours, browse our planets overview, the rocky inner world Mercury, and the small bodies of the asteroid belt just beyond Mars’s orbit.

Frequently asked questions

Why is Mars red?

Mars is red because its surface soil and dust are rich in iron oxide — the same compound as common rust. Iron in the Martian crust oxidised over billions of years, and fine reddish dust now coats the planet and fills its thin atmosphere, giving Mars its characteristic orange-red colour.

When is the next Mars opposition?

The next Mars opposition is around 19 February 2027. The most recent one was on 16 January 2025, so Mars is not at opposition during 2026 and appears relatively small and faint that year. Oppositions recur roughly every 26 months as Earth catches up to and passes Mars.

Can you see Mars without a telescope?

Yes. Mars is easily visible to the naked eye and looks like a bright, non-twinkling orange star. It is most striking around opposition; far from opposition, as in much of 2026, it appears as a modest orange point. A simple planetarium app will show you exactly where to look on any given night.

What can you actually see on Mars through a telescope?

With a 6-inch or larger telescope at 200x or more during good seeing, you can see the bright white polar cap, dark surface markings such as Syrtis Major, and occasionally clouds or dust storms. The disc is small, so high magnification, steady air and patience at the eyepiece are essential.

How do astrophotographers get sharp images of Mars?

They use lucky imaging: recording a high-frame-rate video of thousands of frames, then stacking only the sharpest ones in software like AutoStakkert and sharpening with wavelets. A Barlow lens brings the effective focal ratio to about f/15–f/20, and short capture runs prevent Mars’s rotation from smearing surface detail.