The universe is about 13.8 billion years old. Venus is the hottest planet due to a runaway greenhouse effect. Elliptical galaxies are the most common type. Stars produce energy through nuclear fusion.

If you look across space with a telescope, you’ll see countless galaxies, most of which host large central black holes, ...

The universe is generally referred to as infinite, unknown, and limitless. With over 2 trillion galaxies and millions of stars and planets, the universe is so enormous that it stretches the boundaries ...