When compared to that hypothetical road trip your family may take across ten states to the Grand Canyon, Mars is considerably further away. Let’s put this into perspective: If you happen to be standing in your back yard some night, chances are that you will be able to see Mars. To the naked eye, the object will look like one of the thousands of visible stars looming above, but it will have a reddish, orange hue. Furthermore, Mars is not a star, but the fourth planet out from our sun in this solar system. It is roughly half the size of Earth. It appears to be no larger than an eraser on the end of a pencil at a distance of about ten feet because its average distance from the sun is some 227.9 million kilometers.
Our planet Earth is by contrast only about 150 million kilometers from the sun. As you observe this red speck in the sky, you are looking at an object half the size of our world that lies nearly 78 million kilometers away! (Or, for those more comfortable with English measurements; about 48 million miles away.) These distances are average. At times, the planet will be closer to the sun as well as Earth due to the characteristics of its orbit. If the revolution of the planets were circular in nature, then they would always be the same distance from the sun. Since they are instead elliptical, this is not the case. As a result, the distance between Earth and Mars, which also orbit the sun at different velocities, can be as close as 36.9 million miles when the two planets are on the same side or as far as 247.25 million miles when they lie on opposite ends. Depending on your starting point, it may take two or three days to reach a vacation spot such as the Grand Canyon, but at an average driving speed of 60 mph, it would take approximately 91 years and 4 months to reach Mars at its average distance from your driveway!
Since Mars; also known as the Red Planet, is so far away from the sun in comparison to Earth, it’s a bit chillier there as well. The average, or mean, temperature is about 81 degrees Fahrenheit below zero. It can get as warm as 68 above at or near the equator and conversely as cold as 220 below zero in the Polar Regions. In comparison, our continent of Antarctica would seem almost tropical. Being further away from that source of heat known as the sun has a way of doing this. Planets further out are even colder, while the closer planets of Venus and Mercury have surfaces so hot that a human would be incinerated in a matter of seconds.
In the centuries preceding modern space exploration, Mars was believed to have the best chances of harboring life forms as we on Earth enjoy. In 1965, these hopes were all but dashed when Mariner 4 detected nothing but rocks, sand, and moon-like craters. Later, the Viking Landers of the 1970’s identified water, but no evidence of living organisms. Whether or not life once existed on Mars is still subject to speculation.
As we enter the second decade of the 21st century, plans to send humans to the Red Planet are in the works. Once we have crossed this threshold, we will undoubtedly become far more enlightened in our knowledge of this world.
As they say, progress is always something to look forward to.
