We measure the extremely long distances between things in space by light years. A light year is the distance that light travels in one Earth year. Light travels at about 300,000 kilometres per second.

Neptune is called an “ice giant” because it’s mostly made of a thick, slushy mix of water, methane, and ammonia, which ...

“This is a big step in understanding the outer solar system,” said Dr. Rosemary Pike, lead researcher from the Center for Astrophysics | Harvard & Smithsonian. “It shows that even very distant regions ...