Galaxies • A galaxyis a large group of stars, dust, and gases. • They come in variable sizes and shapes. • The largest have over a trillion stars.
Types • In the 1920’s— Edwin Hubble beganclassifying galaxies-mostly by theirshape. • Spiral Galaxy • EllipticalGalaxy • IrregularGalaxy
Spiral Galaxies • Spiral galaxies bulge at the center and have arms that spiral. • The arms are made of gases, dust, and new stars that formed in the denser regions. The Milky Way is believed to be a spiral galaxy
Elliptical Galaxies • Cucumbershaped, verybrightcenters and verylittledust and gas • About 1/3 of all galaxies are classified as elliptical. • Usuallycontainold stars. • Hugeelliptical galaxies are calledGiantElliptical • Smallerelliptical galaxies are calleddwarf galaxies Giant Elliptical
Irregular Galaxies These are basically the galaxies that did not “fit” into the other categories. They are often companions of Large Spiral Galaxiesthat could be the cause of their irregular shapes.
Content of Galaxies • Billions of stars • gasclouds ( Nebulas) • planetarysystems.
Nebula • Clouds of gases • Regions where new stars are born • Region where stars explode when they die • Spiral Galaxies usually contain Nebulas
Star Clusters 1. Globular cluster: a group of stars that looks like a ball and contains up to 1 million stars • Found in « halo » that cansurround a spiral galaxy
Star Clusters 2. Open Cluster: Group of closely packed stars that are usually located along the spiral disk of a galaxy. • Newly formed Open Clusters have bright BlueStars • There may be a few 100 to a few 1000 stars
Objectives 10/24/2013 8th Grade Please enter quietly & begin the warm-up immediately WARM UP: Please take out your Review Sheet AND your 2-3 Galaxy Notes. Take this time to cut out the Domino pieces. Agenda: • DOMINO Review • Finish 2.3 Notes (Galaxies) • BrainPop- BIG Bang • Go over Review Sheet ?’s GOAL: • I will be Learn about the 3 types of galaxies and their unique characteristics. HWK: STUDY!!! AND Moon Calendar
Quasars • They are amongthe mostpowerfulenergy sources in the universe. • They are caused by massive black holes • They are starlight sources of light extremely far away. • Among the most distant objects in the space.
The Doppler Effect Doppler effect- as a car approaches it sounds higher in frequency (pitch). The same thing occurs with light. Moving Away - redshift Moving Towards - blueshift