10. Mars: Earth's cousin
Bearing a similar tilt to Earth – Mars has a 25° tilt while our planet has a 23.5° tilt – Mars also experiences the same four seasons, though they are more extreme.

9. Could we breathe on Mars?
Though the red planet is often cited as a potential second Earth, we would not be able to breathe in its atmosphere made up of 96% carbon dioxide and less than 0.2% oxygen. Earth’s 21% oxygen is right about where we need to be. Scientists are currently testing microbes that can be sent ahead of humans to begin converting and creating oxygen on the planet.

8. The first assumption of life on Mars
7. Mars' rotation around the sun
A Martian year is significantly longer than an Earth year (the time it takes to make one rotation of the sun). On Earth, we have 365 days whereas Mars has 687 days.
6. Martian day

5. The Curiosity Rover
One of the primary goals of NASA’s well-known Curiosity Rover, currently on the Martian surface, has been to plan for a human visit to the planet. Other goals are understanding the climate and geology of the planet and determining if life ever existed on Mars.
4. First spacecraft exploration of Mars
The first spacecraft sent to explore Mars was the Soviet Union’s “Mars 1” in 1962. En route, mission controllers lost contact with the vehicle. The first American spacecraft to reach Mars was Mariner 4 in 1964 which sent back the first pictures of the red planet.
3. Water on Mars
Astronomers have known for years that water exists on Mars, locked up in its polar ice caps. However, they’ve recently found dark streaks on the planet which would indicate flowing water. Mars’ temperatures (#16) would mean the water would have to be incredibly salty to keep it in liquid form.

2. Martian land area
Despite being considerably smaller than Earth – about half of Earth’s diameter and a tenth of its mass – Mars has a land area similar to that on Earth due to our planet’s high amount of water. This would only apply to Mars’ current state since the Martian oceans have dried and frozen up.
1. Martian size
Volume-wise, Mars is much smaller than Earth. Over six whole Mars’ would be able to pack into our Earth.

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