Besides the earth, what is another planet that once had oceans?

Among the eight planets in the solar system, Mars is another planet that once had oceans besides the Earth. Mars is the fourth closest planet to the sun, the second asteroid in the solar system after Mercury, and one of the four terrestrial planets in the solar system.

In ancient Europe, Mars was called "Mars", and the "God of War" in ancient Roman mythology was also called "Red Planet". In ancient Chinese, it was called flicker because, like fire, its position and brightness often changed. Its orange appearance is due to the surface covered with hematite (iron oxide). The diameter of Mars is about half that of the Earth, and the rotation period from the tilt of its axis is similar to that of the Earth, but period of revolution is twice as large as the Earth. The brightness of Mars can be as high as -2.9, but it is darker than Jupiter most of the time.

brief introduction

The atmosphere of Mars is mainly carbon dioxide (95.3%), which is thin and cold, spreading all over craters, canyons, sand dunes and gravel, and there is no stable liquid water. The southern hemisphere is an ancient highland full of impact craters, while the northern hemisphere is a younger lowland plain. Mars has the largest known mountain in the solar system-Mount Olympus, and the largest canyon-Mariner Canyon.

Mars has two natural satellites: Phobos and Phobos, which are irregular in shape and may be captured asteroids. According to the observed evidence, Mars has observed a phenomenon similar to groundwater gushing, and the Antarctic ice sheet has partially retreated. Radar data show that there are a lot of water ice under the polar and mid-latitude surface.