Mars is a cold and dead world, but it wasn’t always this way. We know water once flowed on Mars. Orbital images reveal its valleys were formed by rivers, while surface experiments have found minerals that require liquid water to form.
Today, however, Mars’s rivers are no more.
It’s thought that the Red Planet’s thin atmosphere is to blame as the low pressure caused most of the oceans to boil away, while temperatures mean any remaining water is frozen.
What isn’t known is how long there was water on the surface.
It could be that ancient Mars was warm enough to hold permanent oceans, but it could also be the case that the water spent most of its time frozen, and only thawed when a volcano eruption or meteor impact heated the planet enough to create a flash flood.
Such eruptions were common in Mars’s early history.
With low gravity and air pressure, the volcanoes on Mars could grow to enormous size and the planet is home to the Solar System’s largest known volcano: Olympus Mons, a huge shield volcano 624km wide and 22km high.
However, the planet’s interior solidified around a billion years after its formation, freezing the planet in this early stage of formation. Could Mars volcanoes still be active?
A section of Elysium Planitia on Mars, as seen by ESA’s Mars Express spacecraft. Credit: ESA/DLR/FU Berlin (G. Neukum), CC BY-SA 3.0 IGO
Facts about Mars
- Diameter: 6792km (0.53 times Earth)
- Mass: 642 billion trillion kg (0.11 times Earth)
- Distance from the Sun: 228 million km (2.45 AU)
- Length of day: 24 hours, 37 minutes
- Length of year: 687 days (1.9 years)
- Number of moons: 2
- Temperature: -143ºC to 35ºC
- No of spacecraft visitors: 25+
- Number of moons: 2
- Type of planet: Rocky
How to observe Mars
Mars and the Pleiades, photographed by
Gábor Szendrői, Hungary, 30 March 2019. Equipment: Canon EOS 700D DSLR camera, Leica APO-Telyt-R 3.4 / 180mm lens.
Mars is best viewed around the time of its closest approach to Earth and opposition, when it appears largest on the sky.
To the naked eye, Mars is bright and has a slightly reddish hue, while through a telescope you should be able to make out the features on the lunar surface.
It is possible to see the planet the rest of the year provided it is visible in the night sky, but it will be much smaller and dimmer.
A view of the Murray Buttes region of Mars, captured by the Curiosity rover. Credit: NASA/JPL-Caltech/MSSS
Why is it called Mars?
Mars is named after the god of war, whose Greek name is Ares, as the planet’s red colour is reminiscent of blood.
Mars’s two diminutive moons are called Phobos and Deimos (meaning fear and dread) after the god’s twin sons that are sometimes depicted as the horses pulling Mars’s chariot.
What missions have explored Mars?
The rim of Jezero Crater – Perseverance rover’s landing place and area of study – captured in a 360° panorama by the Mastcam-Z instrument onboard the rover. Credit: NASA/JPL-Caltech/MSSS/ASU
Mars is probably the most thoroughly explored planet after our own, though it has a reputation for being cursed. Around half of all missions that attempt to travel to the planet have failed.
Despite this, the planet has seen several orbiter missions and a great many landing missions.
These have looked at all aspects of Mars’s geology, particularly focusing in on the history of water on the planet in an effort to predict whether life has ever existed on the planet.
To date, NASA has sent 5 rovers to the planet: Sojourner, Spirit, Opportunity, Curiosity and Perseverance.
The three most recent arrivals at Mars are NASA’s Perseverance rover, the Emirates Mars mission and China’s Zhurong rover.
For more on the new Mars missions, watch our interview with planetary scientist Emily Lakdawalla.
- Mariner programme (1965–71, NASA)
- Viking (1976, NASA)
- Mars Global Surveyor (1997, NASA)
- Pathfinder and Sojourner (1997, NASA)
- Mars Odyssey (2001)
- Mars Exploration Rovers, Spirit and Opportunity (2004, NASA)
- Phoenix (2008); Curiosity (2012, NASA)
- ExoMars Trace Gas Orbiter (2016)
- InSight (2018)
- Perseverance (2021)
Pictures of Mars
Below is a selection of images of Mars captured by astrophotographers and BBC Sky at Night Magazine readers.
For astro imaging advice, read our guide on how to photograph Mars, how to photograph planets or our beginner’s guide to astrophotography.
And if you do manage to capture an image of Mars, we’d love to see it! Don’t forget to send us your images or share them with us via Facebook, Twitter and Instagram.
Mars passing the Beehive Cluster by Mark Casto, Halesworth, Suffolk, UK. Equipment: Lumix G1, Skywatcher 200p, Eq5 mount, Single Axis Tracking.
Mars in The Beehive by Frank Ryan Jr, Shannon, Ireland. Equipment: Takahashi FSQ-ED 106mm & SBIG ST-8300C CCD.
Mars by Tom Howard, Crawley, Sussex, UK. Equipment: Celestron C11, EQ6, DBK21 CCD, Televue x2.5 PowerMate.
Mars by Michael Lloyd, Cheshire, UK. Equipment: Skywatcher 254mm (10″) Dobsonian Reflector, 5mm Wide Eyepiece, Fujifilm S4000.
Mars by Lars L, Grönbo, Sweden. Equipment: C-11, PGR Flea 3, Powermate 5, Astronomik RGB.
Mars by Miles Lord, Sandhurst, UK. Equipment:Skywatcher 200p, modified MS LifeCam Studio webcam, IR/UV Cut.
Mars by Martin Reeve, Yeovil, Somerset, UK. Equipment: Celestron CPC800, Canon video camera with eyepiece projection.
Mars 14 March 2012 by Andy Laing, Northamptonshire, UK. Equipment: Skywatcher 127mak, 2x Barlow, green filter & DMK21AF02.AS mono
Mars from SE London, March 24 by Jim Thurston, London, UK. Equipment: Celestron 9.25″ SCT, EQ6, DMK21AU618, Astronomik LRGB filters.
Mars by Alastair Woodward, Derby, UK. Equipment: 8″ Manual Dob., Canon 350d.
Mars by Chris Garry, Cambridge, UK. Equipment: C14, x2.5 Powermate, ASI120MC
Mars IR-RGB by Stephen Jennette, Morecambe, UK. Equipment: DMK21au618, Baader LRGB filters, Celestron C11, Televue Powermate 2.5, Skywatcher EQ8 mount
Mars IR-RGB by Stephen Jennette, Morecambe, UK. Equipment: Celestron Cll, DMK21au618, Baader RGB filter, Powermate 2.5
Mars 18042014 on a cloudy night by Alan Kennedy, Ferryhill, County Durham. Equipment: 8″ SCT, NEG6 mount, ZWO ASI120MC, 2x Vixen barlow.
Mars at Opposition by Bill McSorley, Leeds, UK. Equipment: Celestron 5se, QHY5l-ii, Celestron 2x Barlow.
Mars by Martin Pyott, Detmold, Germany. Equipment: Skywatcher 127mm Maksutov, Synscan AZ goto mount, 2x Celestron Ultima Barlow, QHY IMG132E Planetary CMOS camera.
Mars by John Chumack, Dayton, Ohio, USA. Equipment: C8 (2000mm), QHY5IIL CCD, 3x Barlow.
Mars with Skywatcher 150/750 by Houssem Ksontini, Tunis, Tunisia. Equipment: Skywatcher 150/750, Neq3-2 mount, Webcam Logitech C270, Barlow x3
Mars at Opposition by Matt Watson, Sydney, Australia. Equipment: Takahashi Mewlon 250, Losmandy G11, ZWO ASI174MM mono, Baader RGB filters, A Televue 3x Barlow
Mars at Opposition by Alexei Pace, Malta. Equipment: QHY5III, EdgeHD 14
Mars at Opposition, 2016 John Chumack, Dayton, Ohio, USA. Equipment: C8, Qhy5IIL CCD, 2x barlow.
Mars Planet by Ronald Piacenti Jnr, Norma Observatory, Brasilia-DF, Brazil. Equipment: Celestron C6, HEQ5PRO, ASI120MC, Barlow 2X, Moon & SkyGlow Filter
Mars by Paul Williamson, Abu Dhabi. Equipment: C11, ASI 224 CCD.
Watercolor of the planet Mars in Scorpios by Michel Deconinck, Artignosc-sur-Verdon, Provence, France. Equipment: Bresser 4″/1000mm refractor
Mars by John Chumack, Dayton, Ohio, USA. Equipment: C8, 5X Barlow, QHY5IIL CCD.
MARS & Rho Ophiuchi – Aug 26, 2016 by Sebastian Voltmer, Siding Spring, Australia. Equipment: Takahashi FSQ ED, FLI Microline 16803.
Olympus Mons, the largest volcano in the Solar System by Avani Soares, Parsec Observatory, Canoas, Brazil. Equipment: C14 Edge, ASI 224, Powermate 2X, L filter
Mars by Avani Soares, Parsec Observatory, Canoas, Brazil. Equipment: C14 Edge, ASI 224, Powermate 2X, L filter
Mars, April 28-2018 by Avani Soares, Canoas, Brazil. Equipment: C14 HD, ASI 290 MC, PM 2X, L filter
Mars by Fernando Oliveira De Menezes, Sao Paulo, SP, Brazil. Equipment: C11 edge, So 290mc, Powermate 4x