Learn where the atmosphere ends and space begins. See why it's difficult to set a single value for where outer space starts.
Astronomy
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 Recently updated !
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? Recently updated !
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? Recently updated !
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 Recently updated !
It never gets truly dark at night because of an effect called airglow. Airglow is similar in color to the aurora, but you don’t have to visit a polar region to see it. While the aurora is light released by the interaction between magnetosphere and the solar wind, airglow is […]
What Is Airglow? Why the Night Sky Is Never Truly ... Recently updated !
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. […]