What keeps everything in space moving?

Everything in space is always moving. Earth circles the sun, the sun orbits around the center of the galaxy, and even galaxies move. But why is everything in space in constant motion?

According to Edward Gomez, an astrophysicist, it all started with the Big Bang. This huge explosion, which happened a long time ago, caused everything to expand outward. "From the very beginning, the universe started expanding because of the Big Bang," Gomez explains. This initial movement set the stage for everything in the universe to keep moving.

Carol Christian, another astrophysicist, adds that this constant movement is like an imprint from the universe’s beginning. "The beginning was all about movement, so movement has been part of the universe from the start."

The expanding universe affects very large objects. As the universe grows, the space between distant objects gets bigger. This makes it seem like objects are moving farther apart, but they aren't actually moving through space. Instead, the space between them is expanding.

On a smaller scale, things in space spin because of something called angular momentum. When two objects come close to each other, their gravity pulls them together. If they don't collide, they usually start to orbit around each other. This spinning effect is seen everywhere, from tiny dust particles to huge galaxies.

Gomez explains that the solar system was created in a way similar to how pizza dough is spun. As the dough spins, it flattens out into a disc. Similarly, the solar system formed from a spinning cloud of gas and dust, which flattened into a disc shape due to angular momentum. This spinning force keeps the planets orbiting the sun.

Galaxies also spin, but in a surprising way. Gomez notes that stars further out in a galaxy should spin more slowly than those near the center. However, they don’t, which suggests the presence of dark matter. Dark matter is a mysterious substance that doesn’t emit light, so we can't see it directly, but it has mass and affects the movement of stars.