The Red Planet is, in many ways, the planet that is most like Earth, which is probably why our science fiction is filled with stories of Martians. Percival Lowell even drew maps of the canals built by Martians. In the early 20th century, an organization offered a cash prize to the person who first communicated with an alien civilization. But Mars was excluded because, at that time, everyone knew that Mars was inhabited by intelligent creatures! But our first close-up images of Mars from Mariner 4 were a little disappointing to those who imagine Mars to be inhabited. Subsequent pictures have shown Mars to be a place that may have once been hospitable. It is now believed that Mars once had an extensive ocean. Mars may have even had plate tectonics in the past.Mars has approximately the same period of rotation as Earth. One synodic rotation is called a sol. What is the time on Mars at the Curiosity rover right now? You can have the time on Mars displayed on your computer. It has polar ice caps which consist of frozen water and carbon dioxide. We occasionally see clouds in Mars' thin atmosphere. In the spring on Mars, the carbon dioxide in the polar cap sublimates and the increase in atmospheric pressure causes huge dust storms to form. Occasionally, one sees dust devils moving across the surface. The surface temperature is never higher than about 10 degrees Celsius. Here's the latest Martian weather report!
Mars has a radius of 3396 km, which is approximately one half that of Earth. This gives the planet about the same surface area as the land area of Earth.
Mars rotates in 24 hours 37 minutes at the sidereal rate, referenced to the stars. Its synodic day, from noon to noon, is 24 hours 39 minutes. This is very near Earth’s rate of rotation. The day on the surface of Mars would seem very familiar to an earthling.
Mars orbits the Sun at an average distance of 1.52 A.U. and takes 1.87 years to complete one revolution. Because of its axial tilt, it has seasons, just as Earth. But each of its seasons is about twice as long.
The atmosphere of Mars consists of 96% carbon dioxide. The remaining 3% is mostly nitrogen. The pressure at the surface varies from from 4.0 to 8.7 mb (depending on season). We occasionally see cloudsin Mars' thin atmosphere.
Since it lacks an appreciable iron core, Mars has no self-generated magnetic field. This results in radiation levels at the surface that would be harmful for human beings.