Questions people actually ask
Short answers, each with its source. Longer ones live on the topic pages.
Why is Mars red?
It’s called the Red Planet because iron minerals in the Martian dirt oxidise, or rust. NASA Science: Mars facts
How big is Mars?
With a radius of 3,390 km, Mars is about half the size of Earth. NASA Science: Mars facts If Earth were the size of a nickel (a US 5-cent coin), Mars would be about as big as a raspberry. NASA Science: Mars facts
How far away is Mars?
Mars orbits at an average distance of 228 million km from the Sun, which is 1.5 times Earth’s distance (1.5 AU). NASA Science: Mars facts Mars and Earth are never closer than 54.6 million km, and they can be as far apart as 401.4 million km. NASA NSSDC: Mars fact sheet
How long is a day on Mars?
A day on Mars lasts 24.6 hours, a little longer than Earth’s. Martian days are called sols, short for “solar day”. NASA Science: Mars facts Measured from noon to noon, a Mars day averages 24.6597 hours and an Earth day 24.0000 hours. NASA NSSDC: Mars fact sheet
How long is a year on Mars?
A year on Mars lasts 669.6 sols, which is the same as 687 Earth days. NASA Science: Mars facts
How much would I weigh on Mars?
Gravity on Mars is about a third of Earth’s. If you weigh 100 pounds on Earth, you would weigh 38 pounds on Mars. NASA: Humans to Mars
Could I breathe on Mars?
Mars has a thin atmosphere made mostly of carbon dioxide, nitrogen and argon. NASA Science: Mars facts Mars’s air is 95.1% carbon dioxide and only 0.16% oxygen. NASA NSSDC: Mars fact sheet
How cold is Mars?
The average temperature on Mars is about −59 °C. NASA NSSDC: Mars fact sheet Temperatures on Mars can reach 20 °C or drop to about −153 °C. NASA Science: Mars facts
Is there water on Mars?
There is water on Mars today, mostly as ice just under the surface near the poles. The air is too thin for liquid water to last long on the surface. NASA Science: Mars facts There’s evidence of liquid salty water in the ground on some Martian hillsides. NASA Space Place: All about Mars
Is there life on Mars?
Scientists don’t expect to find anything living on Mars today. They are looking for signs of life from long ago, when Mars was warmer and wetter. NASA Science: Mars facts · checked 25 Oct 2026
How many moons does Mars have?
Mars has two small moons, Phobos and Deimos. NASA Science: Mars moons · checked 25 Oct 2026
How many rovers are on Mars?
NASA has sent five rovers to Mars: Sojourner, Spirit, Opportunity, Curiosity and Perseverance. NASA Space Place: The Mars rovers · checked 25 Oct 2026
When will people go to Mars?
NASA is working on technology to send astronauts to Mars as early as the 2030s. NASA: Humans to Mars · checked 25 Oct 2026
Most Mars numbers here come straight from NASA’s Mars facts page and NASA’s Mars fact sheet. Different NASA pages sometimes round differently (for example, Mars’s air is “95.1%” carbon dioxide on the fact sheet and “96%” on another page). Records and mission counts change, so they carry the date we checked them.