See how to choose a telescope. Learn the difference between reflectors vs refractors, types of mounts, and other factors you should consider.
Astronomy
Learn what right ascension and declination mean (RA and DEC) and how to use them to find stars, planets, and other celestial objects.
Right Ascension and Declination Recently updated !
Learn where the atmosphere ends and space begins. See why it's difficult to set a single value for where outer space starts.
Where Does Space Begin? The Kármán Line Recently updated !
Learn what the zodiacal light is. Find out what it looks like. Determine the best time and location to see it.
What Is the Zodiacal Light? When and How to See ... Recently updated !
Learn the difference between meteoroids, meteors, meteorites, comets, and asteroids.
Difference Between Meteoroids, Meteors, Meteorites, Comets, and Asteroids
Find out which element is the most abundant element in the universe. See the abundance of other elements, too.
What Is the Most Abundant Element in the Universe?
One easy way to calculate your weight on other planets is to multiply your weight on Earth by the ratio between gravity on another planet and Earth.
How to Calculate Weight on Other Planets
The moon rotates, completing one rotation each month so we only see one side.
Does the Moon Rotate on Its Axis?
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 […]