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, join together, and start nuclear fusion. Creation of a Star

Nuclear Fusion: Hydrogen molecules join together into helium – Releases massive amounts of heat and light energy -- Makes stars glow

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

Lifetime: Approximately 9 billion years Converts hydrogen to helium Lifetime: Approximately 9 billion years Converts hydrogen to helium Average Stars (such as our sun)

 Hydrogen begins to runs out a  Nuclear fusion can no longer occur  Outer layers cool and expand outward Red Giant – large, cooling star that is running out of hydrogen Cool Fact: When this happens to our Sun, scientists hypothesize that it will extend out as far as the Earth or even Mars.

 Core of the Red Giant collapses  Outer layers of the star drift away. White Dwarf – Small, dense star that has burned out all it’s hydrogen Continues to produce heat in the core 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

 White dwarf runs out of energy, cools to become a black dwarf Black Dwarf – small, dead star Cool Fact: There are no known black dwarves in the universe because stars take billion years to cool… that is longer than our universe has existed!

Blue Giant: Lifetime = approximately 10 million years because they use up hydrogen very quickly Size = times the size of the Sun! Super hot Blue Giant: Lifetime = approximately 10 million years because they use up hydrogen very quickly Size = times the size of the Sun! Super hot Path #2: Massive Stars

 Hydrogen starts to run out  Star starts to fuse heavier elements  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 expand to an even larger volume.

Light Echoes From a Red Supergiant NASA Photo

 Massive star runs out of fuel  expands outward, then explodes into a radioactive cloud. Supernova = extremely bright explosion, when a star ejects most of it’s mass Kepler’s Supernova

Crab Nebula: The remains of a supernova

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

After a supernova, one of two things happen to a massive star: Neutron Star Or Black Hole

 Small, dense core keeps collapsing Neutron Star: Gravity continues to press in on the star, causing it to create neutrons Pulsar: Rotating neutron star, releasing pulses of light and radio waves 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!"

 The core of the most massive stars (at least 10x larger than the sun) 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.