On a smaller scale, things in space spin because of something called angular momentum.
Everything in space is in constant motion. The Earth revolves around the Sun, the Sun orbits the center of the galaxy, and even galaxies move. But why is everything in space in constant motion?
According to astrophysicist Edward Gomez, it all started with the Big Bang. This massive 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 a trace of the beginning of the universe. “The beginning was all motion, so motion has been part of the universe since the beginning.”
The expanding universe affects very large objects. As the universe grows, the space between distant objects becomes larger. This makes it appear as if objects are moving away from each other, but they are not 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 approach each other, their gravity pulls them together. If they don't collide, they usually start orbiting 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 similar way to how pizza dough is spun. As the dough spins, it flattens out into a disk. Similarly, the solar system was formed from a rotating cloud of gas and dust, which flattened into a disk due to angular momentum. This spinning force keeps the planets in orbit around the sun.
Galaxies also spin, but in surprising ways. Gomez notes that stars farther away from a galaxy should spin more slowly than those closer to the center. However, this is not the case, suggesting the presence of dark matter. Dark matter is a mysterious substance that does not emit light, so we cannot see it directly, but it has mass and affects the motion of stars.