Jupiter was known during ancient times as one of the "wanderers" in the night sky, its name identified with the god of the sky and thunder.
Until the year 1610, it was known to most people as nothing but a small star like object in the sky. In that year however, the Italian astronomer Galileo Galilei peered at the heavens with a simple telescope. Focused on Jupiter, Galileo observed four tiny "stars" forming a line through the planet and after many nights of careful observations he concluded that these objects were not stars at all, but smaller planets orbiting around Jupiter. It was part of a revolutionary breakthrough in the view of the universe at that time, helping to support a theory that the Earth was not the center of everything and providing a stepping stone for the development of our current view of the universe.
Jupiter is the largest of eight planets in our solar system. It is so large that you could fit a dozen Earths in a line across its equator. However, the king of planets is very different than Earth. Jupiter is a gas giant with no solid surface to stand on. If someone were to try and land on Jupiter, they would simply descend through the clouds into a thicker and thicker atmosphere until the pressure and heat became too great to bear. We know this due in a large part to an unmanned spacecraft appropriately named Galileo that was launched in 1989 to study the great planet and its many moons.
Jupiter has 67 natural satellites (moons) of which four are quite large. Ganymede, Callisto, Europa and Io (pronounced eye-oh) are called the Galilean moons and are the objects Galileo himself observed orbiting Jupiter more than 400 years ago. At the end of its mission in 2003, the Galileo craft, having exhausted most of its fuel, was sent plunging into Jupiter's atmosphere to prevent a possible collision with and subsequent bacterial contamination of Europa which was a focus of interest for some time. Scientists believe this moon may have an ocean of liquid water beneath its frozen surface with the possibility of extraterrestrial microbial life.
There are those who theorize that we would not be here today if it were not for Jupiter. They believe that in the early solar system, Jupiter's large mass and gravitational pull acted like a vacuum cleaner, gobbling up asteroids and comets that might have otherwise made it into the inner solar system and caused serious problems for Earth. In July of 1994, Jupiter provided evidence to help support this theory when it tore apart and then gobbled up comet Shoemaker-Levy 9. It was a spectacular event with piece after piece of the fragmented comet slamming into Jupiter's atmosphere and leaving temporary "scars" as big as Earth itself. Not long after, in 2009, 2010 and again in 2012, astronomers observed evidence of other impacts in the atmosphere of Jupiter. So it appears that Jupiter to this day is still cleaning up debris left from the formation of our solar system.
With our roll-off roof facility up and running, astronomers of the Adirondack Public Observatory are eager to dazzle you with telescopic views of the moon and cosmos every first and third Friday of each month (next on Feb. 21).
Go to the APO website at apobservatory.org, and click on "events" for more information and directions to our site above Little Wolf Pond in Tupper Lake. Listen for Aileen on North Country Public Radio about once a month during "The Eight O'Clock Hour" or email Aileen with any questions at firstname.lastname@example.org.