Visibility Check
Analyze real-time astronomical and meteorological data for Mars.
Mars
RockyMars · Solar System
The fourth planet from the Sun, known as the Red Planet due to its reddish appearance caused by iron oxide on its surface. Mars has the tallest volcano in the Solar System, Olympus Mons.
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About Mars
A cold desert that was once warm and wet, holding the tallest volcano and deepest canyon in the solar system.
Extremes of terrain
Mars is roughly half Earth's diameter but carries landforms on a scale Earth cannot match. Olympus Mons rises about 21.9 km — two and a half times the height of Everest above sea level — and spans roughly the area of France. Valles Marineris runs over 4,000 km along the equator, up to 7 km deep; placed on Earth it would stretch from New York to Los Angeles.
The reason is the absence of plate tectonics. On Earth, a volcanic hotspot builds an island and the moving plate carries it away, producing a chain of modest volcanoes like Hawaii. On Mars the crust does not move, so a hotspot piles material in one place indefinitely. Lower surface gravity lets the resulting structure stand taller before it collapses under its own weight.
The water that was there
The evidence for ancient surface water is now extensive and comes from several independent directions. Orbiters have mapped river valley networks and sediment deltas. Rovers have found clay minerals and hematite that only form in prolonged contact with liquid water. Curiosity drove across the bed of what was unmistakably a lake in Gale Crater, reading layered sediments deposited over millions of years.
So Mars had rivers, lakes and possibly a northern ocean, roughly three to four billion years ago — around the same period life was gaining a foothold on Earth. Whether it also gained one on Mars is the central open question in planetary science, and it is the reason Perseverance is drilling and sealing rock cores in Jezero Crater for a future mission to bring home.
How the atmosphere was lost
Present-day Mars has a surface pressure under 1% of Earth's, almost entirely carbon dioxide. Liquid water cannot persist there; it boils or freezes.
The explanation involves the planet's core. Mars once had a global magnetic field, recorded in the magnetisation of its oldest crust, but the small core cooled and the dynamo shut down early. Without a magnetic shield, the solar wind struck the upper atmosphere directly and stripped it away over billions of years. NASA's MAVEN orbiter has measured this loss actively happening and quantified the rate, and it rises sharply during solar storms. Mars did not merely dry out — it was gradually scoured.
The most-visited planet
Mars has received more robotic visitors than anywhere else beyond Earth. Sojourner arrived in 1997; Spirit and Opportunity followed in 2004, with Opportunity operating for fourteen years against a ninety-day design life. Curiosity landed in 2012 and is still working. Perseverance arrived in 2021 carrying Ingenuity, a small helicopter that made the first powered flight on another world and went on to fly seventy-two times before damaging a rotor blade.
Ingenuity mattered beyond the novelty. The Martian atmosphere is so thin that flight was widely considered impractical, and proving otherwise opened aerial survey as a genuine option for future exploration.
How to see it yourself
- Best time of year
- Around opposition, roughly every 26 months
- Equipment needed
- Naked eye; a 100 mm telescope shows surface detail near opposition
- Finding it
- Mars is recognisable by its steady orange-red light — it does not twinkle the way stars do. It is worth planning around opposition, when Earth passes between Mars and the Sun and the planet is closest, largest and visible all night. Between oppositions it shrinks to a disappointing dot even in good telescopes.
Sources
- Mars — NASA Science
- MAVEN mission — NASA
- Mars Perseverance rover — NASA