Solar System Astronomical Units Chart

The Solar System formed 4. 6┬ábillion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system’s mass is in the Sun, with the majority of the remaining mass contained in Jupiter. The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal. The four outer planets are giant planets, being substantially more massive than the terrestrials. The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane. All eight planets have almost circular orbits that lie within a nearly flat disc called the ecliptic.



So mark your calendar for the 16th June 2015 This is an awesome event itself but on this night you will have an amazing chance to view our celestial neighbors These icy moon-worlds are the next important step in the scientific quest for the Holy Grail of life beyond our own planet. It is a strange era in human history. Astronomers have collected large amounts of data revealing bewitching clues that habitable ocean moon-worlds may be out there, within the family of our very own Star. Humanity is poised at the beginning of a new era. Sophisticated new technology might very soon answer the profound, and very ancient question, "Are we alone?" There was a time when Earth had no Moon. About 4.5 billion years ago, when our ancient Solar System was still forming, the dark night sky above our primordial planet was moonless. At this time, the Earth was about 60 percent formed, although it did have a differentiated crust, mantle, and core. This was a very chaotic and violent era in our Solar System's past, with planets first forming out of blobs of primordial dust, gas, and rock. During this era, frequently likened to a "cosmic shooting gallery", collisions between the still-forming planets were commonplace. Orbits were not as orderly as they are now.