Mars has many commonalities with our planet, which is often referred to as the "twin Earth".

They are both Earth-like planets; they both have polar ice caps.

And they both had active atmospheres and liquid water on their surfaces at one time.

In other respects, they are very different.

In particular, Mars can be said to be very different from Earth in terms of their respective atmospheres and climates.

For example, whenever it comes to the weather of Mars, the predictions are usually extremely dramatic.

Not only does the weather on Mars vary from day to day, but sometimes even from one small time to another.

This may seem a bit unusual for a planet with a surface gas density of only 1% of Earth's atmosphere.

But when extreme weather and meteorological phenomena strike, Mars is literally in control.

Mars is the planet most similar to Earth, and that "most" is compared to the seven planets in our solar system, excluding Earth, and includes the dwarf planets and all the moons.

But even if it is the most similar, the climate of Mars is very different from that of Earth.

Except for Earth, none of the other planets in the entire solar system has liquid water on the surface so far, and Mars has not yet been discovered.

The Martian atmosphere is mainly composed of carbon dioxide, and is extremely thin, with a density of only about 1% of the Earth, and a surface pressure of about 0.7% times that of the Earth.

The Martian day and Earth time is about the same, the average Martian day is 24 hours 39 minutes 244 seconds, so that the day and night felt in Mars and Earth is about the same.

Mars rotation axis inclination is 25.19 °, and the Earth 23.44 ° not much difference, so Mars has and Earth about the same four seasons a year.

However, Mars orbit is about 1.5 times as far from the Sun as the Earth, and the rotation line speed is slightly slower than the Earth, 24.13km/s.

Therefore, Mars has a year of about two years on the Earth, 686.98 days, and each season is almost twice as long as the Earth.

So far, the Earth is the most suitable for human habitation of the Earth, so why and the Earth is most similar to Mars can not be inhabited by humans?

There are several main reasons.

1. The atmosphere of Mars is thin, only one percent of the Earth.

2. Due to the thin atmosphere, carbon dioxide and can not form the greenhouse effect, Mars temperature has been maintained below zero, the average summer temperature of negative 50 degrees, the coldest winter negative 120 degrees.

3. There is almost no oxygen on Mars, people will immediately suffocate.

4. Because of the thin atmosphere, so a lot of ultraviolet light can shine on the surface of Mars.