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GALACTIC UNIVERSE. Twinkle, twinkle, little star, how I wonder what you are?. What are stars? And what are they made of?. Stars are huge, hot, bright balls of gas. Stars have different temperatures. Stars are of different colors. Stars are made of different elements.
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Twinkle, twinkle, little star, how I wonder what you are? • What are stars? • And what are they made of?
Stars are huge, hot, bright balls of gas. • Stars have different temperatures. • Stars are of different colors. • Stars are made of different elements.
Stars are of different colors. Betelgeuse Rigel Which star is hotter?
Composition of Stars • Stars are made of different elements in the form of gases. • A star is very dense and hot. • The outer layers of a star (atmosphere) are made of cooler gases (elements). • The elements emit certain wavelengths of light (fingerprints)
The Fingerprints of Elements Emission Spectral Lines Hydrogen Helium Neon Sodium Mercury
What is a Galaxy? It is a group of billions and billions of stars held together by gravity.
Spiral Galaxy Bulge Disk Side View Top View • Huge; contains stars, gas, and dust • Held together by gravity • Pinwheel shape/looks like a hurricane • Bulge and thin disk • Halo (glow) is present • Rich in gas and dust • Young and old stars are present
Elliptical Galaxy • Huge; contains stars, gas, and dust • Held together by gravity • Round to oval • Bulge but no disk • Halo is present • Little cool gas and dust • Mainly OLD STARS are present
Irregular Galaxy • Huge; contains stars, gas, and dust • Held together by gravity • No regular shape • May show signs of a disk and/or bulge • Halo is present • Usually rich in gas and dust • Young and old stars are present
Nebulae Stellar Nebula (where stars are born) Planetary Nebula (death of a star) Movie
Betelgeuse Rigel Orion Constellation
Top View Side View Elliptical Galaxy Irregular Galaxy