Giant clouds of gas and dust The birthplace of stars! Nebula

Eagle Nebula: 9.5 Light Years Tall!

 Hydrogen gas is pulled together by gravity. It begins to spin, heats up, and becomes a star. Creation of a Star

Cool Fact: Hydrogen in its core is converted into helium – this creates massive amounts of heat and light energy (this is called nuclear fusion)

A star will take one of two paths during its lifetime…

Lifetime: Approximately 9 billion years as a main sequence star Average Stars (such as our sun)

 Hydrogen runs out. The outer layers of the star cool and expand outward Red Giant – cool, large, red star Cool Fact: When this happens to our Sun, scientists hypothesize that it will extend out as far as the Earth or even Mars.

 The core of the Red Giant collapses and becomes a White Dwarf. The outer layers of the star drift away. White Dwarf – Small, dense star Cool Fact: Typically, a white dwarf has a radius equal to about 0.01 times that of the Sun, but it has a mass roughly equal to the Sun's. This gives a white dwarf a density about 1 million times that of water!density

 When the white dwarf runs out of energy, it eventually cools to become a black dwarf Black Dwarf – small, dead star

Lifetime = approximately 10 million years Size = times the size of the Sun! Lifetime = approximately 10 million years Size = times the size of the Sun! Path #2: Massive Stars!

 Hydrogen runs out. The outer layers of the star cool and expand outward. Red Super Giant – Very large, cool, red star

They continue to burn for a time and expands to an even larger volume.

Light Echoes From a Red Supergiant NASA Photo

 When a star dies, it explodes into a radioactive cloud. Supernova = extremely bright explosion (brighter than an entire galaxy)! Kepler’s Supernova

Crab Nebula: The remains of a supernova

Cassiopeia A (Cas A, for short), the youngest supernova remnant in the Milky Way.

 What is left after the Supernova is Neutron Star. Neutron Star/Pulsar: When a Neutron Star begins to rotate, it is called a Pulsar. Cool Fact: According to astronomer and author Frank Shu, "A sugar cube of neutron-star stuff on Earth would weigh as much as all of humanity!" Neutron stars can be observed as pulsars.pulsars

 The core of a more massive star will collapse and create a black hole. Gravity becomes so strong not even light can escape (which is why it’s called a “black hole”) Video: Simulation of gravitational lensing by a black hole, which distorts the image of a galaxy in the backgroundgravitational lensinggalaxy

Cool Picture: This is a simulated view of a black hole in front of the Large Magellanic Cloud.