Inhabiting the solar system at comfortable distances from the Sun, Earth and Mars might well have begun their developments with remarkably similar surface conditions. It is this fact that has intrigued planetary scientists and directed the search for life to Mars.
According to popular theories about the formation of the solar system, some four and a half billion years ago an enormous cloud of gas and dust condensed, collapsed, and began to rotate, forming itself into a disk. Overdense regions developed that drew in more material. The largest of these collections of matter became so massive that the pressure and temperature in its center triggered thermonuclear reactions. Our Sun was born. This star at the center of our solar system began to radiate heat and light.
Photo. It would take over one and a quarter million Earths to fill our Sun, which is made up largely of hydrogen and helium gases. Astronomers have estimated the temperature to be around 27 million degrees Fahrenheit at its center and nearly 10,000 degrees F at its surface. Courtesy of NASA.
Other objects formed that were too small to become stars. These smaller orbs became the planets. Two of these planets were similar. Both Mars and Earth formed at a distance from the Sun that was neither too close to the heat of our star nor too far away from its life giving warmth. The temperature allowed water to exist in all three forms, solid, liquid, and gas. Both worlds developed volcanoes that belched out atmospheres of thick gases. The air surrounding the planets trapped heat and kept the surface from cooling too quickly.
As the planets slowly cooled, water condensed from the atmospheres. Long periods of rain made way for oceans, seas, lakes, and rivers. Both Earth and Mars had flowing water covering much of their surfaces. On Earth, lightning in the atmosphere provided the energy, and the oceans provided the water and other chemicals. Eventually complex molecules of carbon, hydrogen, oxygen, and nitrogen formed. Hydrocarbons are present in all forms of life on Earth. To quote the late Carl Sagan, "It is not impossible that..." the same processes which started life on Earth also occurred on Mars.
Mission to Mars. An educational site created for the ThinkQuest contest.