1. PowerPoint made by Sana Gill BLACK HOLES

2. WHAT IS A BLACK HOLE? A black hole is an area in space-time so compact that no matter, not even light can escape from. Black holes grow by capturing close by objects. A black hole’s surface is called the event horizon. Black holes are invisible because no light can escape from it. In order to find black holes astronomers study their effects on nearby objects.

3. FORMATION OF A BLACK HOLE When a star runs out of “fuel” it collapses. Stars the size of our sun become a white dwarf when they collapse, but when an enormous star, 20 times the mass of our sun, collapses it turns into a black hole. The star will become a black hole because it has so strong of a gravity that it keeps on collapsing to a tiny point, that has a gravity so strong that light can not escape. This image taken by the Hubble Telescope shows the remnants of a supernova.

4. TYPES OF BLACK HOLES We know there at least two different types of black holes, a stellar-mass black hole and a supermassive black hole. A stellar-mass black hole is created when a supernova happens (a massive star explodes after running out of its fuel). The stuff left after the supernova collapses into an extremely compact object creating a black hole. The formation of supermassive black holes is unknown, but astronomers think supermassive black holes are at the center of galaxies like our Milky Way galaxy. Supermassive black holes contain as much matter as a million to a 100 million Suns. Astronomers suspect this object (the one boxed in) is a black hole that is bigger than a stellar-mass black hole, but smaller than a supermassive black hole.

5. INTERESTING FACTS A black hole with the same mass of Earth would be around the size of a fingernail. Black holes can contain a volume of space bigger than our solar system. A supernova occurs in the Milky Way galaxy around once every 300 years. When black holes collide there is a massive burst of gravitational energy that could knock a black hole out of the galaxy. Our galaxy is estimated to contain 100 million black holes. Eventually black holes evaporate, giving their energy back to the universe.