redOrbit’s Top 5 Amazing Facts About Mars
Dr. John Millis for redOrbit.com — Your Universe Online
Mars, the subject of human fascination for millennia, is an amazing world with an interesting history. Here, we look at the five most amazing facts about the Red Planet.
1. Mars is only about half the diameter of Earth: We often think of Mars as being quite similar to Earth; a place to visit and potentially inhabit in the future. But while it does bear some similarity with Earth, it is much smaller. In fact“¦
2. The Gravity on Mars is only one-third that of Earth: Here on Earth we are pulled to the surface by gravity. While the same is true on Mars, its gravity is only slightly more than a third of what we experience here on Earth. This is because it is only one half the diameter, and one-tenth the mass, of Earth.
3. Mars has 2 small moons: These satellites, known as Phobos and Deimos, look nothing like our Moon. Instead they more closely resemble asteroids, at least as we traditionally think about them. However, recent research suggests that these Moons were formed by something — possibly another planet forming in the early solar system — colliding with Mars early in its formation; kicking up material from the surface that would later coalesce into rocky objects. This is similar to how our own Moon was thought to have formed billions of years ago.
4. Mars is sometimes the closest planet to Earth: The planet that is closest to Earth varies literally by the day. The distance at which the planets orbit the Sun determines their orbital speed (i.e. the closer they are to the Sun, the faster they travel), so the planets are rarely aligned relative to the Sun. In fact, when this does occur, it is usually cause for excitement in the astronomy community. In August of 2003 Mars and Earth were in such an alignment and were only about 35 million miles apart. At other times, however, Mars can be more than 200 million miles away when they are on opposite sides of the Sun.
5. The surface of Mars can be either extremely cold, or quite warm depending on the time of year: Since Mars is farther away from the Sun than Earth, it is little surprise that the neighboring world is colder than the climate we experience here. But it is the lack of an atmosphere that really makes it cold. Mars has only a thin atmosphere, which means the temperature is much more varied across the surface and, in general, much cooler. The warmest it gets on mars is about 80 degrees Fahrenheit during the “summer” season. But during certain times of the Martian year temperatures can plummet to -225 degrees, while the average temperature is around -67. On Earth our atmosphere partially traps the energy from the Sun near the surface — a process commonly known as the greenhouse effect — which raises the average temperature of the planet.