The dominant force that governs the motion of everything from moons and planets to entire galaxies.
If you want to dive deeper, several highly-rated guides break down these complex topics into manageable "nutshells." Astrophysics in a Nutshell (aka Basic Astrophys...
Because light has a finite speed, looking at distant objects means seeing them as they were in the past. Light from the Sun takes about 8 minutes to reach us, while light from distant galaxies can take millions of years. The dominant force that governs the motion of
Most of what we know comes from studying radiation beyond just visible light, including X-rays, radio waves, and gamma rays. and gamma rays.