Test your knowledge on our solar system, from the biggest and smallest planets to the behemoth mountain on Mars. When you purchase through links on our site, we may earn an affiliate commission.
The solar system is approximately 4.6 billion years old. Astronomers believe that roughly 100 million years into its existence, the planets first began to form in a rotating, flat cloud of gas ...
A planet parade is when several of our solar system's planets are visible ... but all three planets will be under the horizon by 11:30 p.m. to midnight depending on your location.
Planets form in clouds of gas and dust known as protoplanetary disks around young stars. But the formation process of multi-planet systems, like our own Solar System, is still poorly understood.