Astronomy

Get facts about astronomy. Learn about the moon, sun, stars, planets, galaxies, and more.




The light year is a unit of length used to measure vast distances, like between galaxies.
The light year (ly) is a unit of length that is the distance light travels in a vacuum in one Earth year. One light year is approximately 9.46 trillion kilometers (9.46 x 1012 km) or 5.88 trillion miles (5.88 x 1012 mi). The light year is used to describe distances to stars without having to use very […]

What Is a Light Year? Definition and Examples




Astronomers believe it's possible for a moon to have a moon of its own.
We all know planets orbit stars and moons orbit planets. Have you ever wondered whether a moon can have a moon of its own (a submoon)? Theoretically, the answer is yes, but there is a good reason why we haven’t discovered any submoons around moons in our own solar system. […]

Can a Moon Have a Moon?


The average distance between the Earth and the Sun is about 93 million miles. (NASA)
All of the planets, comets, and asteroids in the solar system orbit the Sun. The average distance between the Earth and the Sun is 92,955,807 miles (149,597,870 km). Most people just round it up to 93 million miles. This distance is called an astronomical unit or AU and is used […]

How Far Is the Sun From Earth?