Gravity pulls the dust and gas together to form a protostar. The outward pressure from the expanding hot gases is balanced by the force of the star’s gravity. Our Sun is halfway through its 10 billion year stable phase. Gravity pulls smaller amounts of dust and gas together, which form planets in orbit around the star.

The Sun and the planets formed together, 4.6 billion years ago, from a cloud of gas and dust called the solar nebula.

Asteroids

The small bodies from which the planets formed are called planetesimals. They begin as tiny grains of dust, but, over time, they collect more and more…

Consolidations of these rocky planetesimals formed the four small, dense inner, or terrestrial, planets—Mercury, Venus, Earth, and Mars. Many other icy bodies of planetesimal size and smaller are thought to have remained unconsolidated beyond the orbit of Neptune, forming a debris ring called the Kuiper belt.

Ceres

Black holes are the densest things in the universe. That means that they can fit more matter into a given space than anything else. The smallest black holes may cram as much matter as three million Earths into a single tiny point.

Over time they shrink down to nothing and simply pop away in a flash of energy. It’s not exactly fast. A good size black hole — say, a few times more massive than the sun — will take about 10^100 years to eventually evaporate through this process, known as Hawking Radiation.

White holes

There is consensus that supermassive black holes exist in the centers of most galaxies. The presence of a black hole can be inferred through its interaction with other matter and with electromagnetic radiation such as visible light.