1. Black Holes

2. Index 1- Historical Overview 2- What is a black hole? 3- How are they formed? 4-can we see them? 5-Some facts about black holes. 6-Refernces

3. Historical Overview In 1783 Marquis de Laplace from France and John Michell from England suggested the first theory of black holes

4. In 1969 the term of black holes was mentioned for the first time by the American scientist John Wheeler

5. What is a Black Hole? Laplace suggested that if a star is massive enough it would have a strong gravitational field that light could not escape, which means that any light emitted from the surface of the star would be dragged back. Black hole is defines as the most powerful force in the universe. It’s where the gravity has become so strong that nothing around it can escape.

6. How are they formed? Black holes are formed when giant stars explode at the end of their lifecycle. This explosion called Supernova. Then the star collapses on itself down to a very small size. The gravity will be very strong due to its mass and it became a black hole

7. Can we see Black Holes? Black holes are truly invisible, we can not actually see them because they do not reflect light. Scientists know they exist by observing light and objects around black holes. There is strange things happen around black holes.

8. Some Facts about Black Holes They don’t live forever, but slowly evaporate. Its center where all the mass stays is a point called Singularity. Black holes have the mass of several millions of our sun.

9. References “A Brief History of Time” by Stephen W. Hawking http://www.nasa.gov http://www.ducksters.com http://chandra.harvard.edu

10. Thank You