Earth & Space
Why Do Tides Happen?
Tides happen because the moon's gravity pulls on Earth's oceans unevenly, creating two tidal bulges that coastlines rotate through each day.
tidesmoon
Space
Why Is Earth Round?
Earth is round because gravity pulls matter equally from all directions toward the center, shaping large objects into a sphere over millions of years.
spacegravity
Space
Why Is Gravity Weaker on the Moon?
Gravity is weaker on the moon because the moon has much less mass than Earth. Less mass means less gravitational pull, so objects weigh about one-sixth of what they do on Earth.
spacemoon mass
Where gravity wins completely
What Is a Black Hole?
A black hole is a region of space where gravity is so strong that nothing, not even light, can escape. Here is what they are, how they form, and what falling into one would actually involve.
black holesspace