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Discover the galaxy's wonders - from shapes like elliptical and spiral to clusters and superclusters. Unveil the mysteries of massive collections of stars, gas, and dust in the vast arms of the Milky Way galaxy.
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Obj. 1: What is a galaxy? • The word Galaxy means “A city of stars” • Edwin Hubble is an American astronomer who put galaxies into categories.
Galaxy is a Sun’s Stellar Region massive collection of stars, gas, and dust kept together by gravity
If our solar system was the size of a cell in the human body, our galaxy would still measure over one mile across.
Our Sun belongs to the Milky Way Galaxy- It contains 200 billion stars which are grouped in a flatten disc which bulges in the center. • It is about 100,000 light years in diameter
Obj. 2 Describe 4 types of galaxies • Edwin Hubble classified galaxies according to their shape (1920-30) • Four Classes: • Elliptical • Spiral • Bar Spirals • Irregular (no clear shape) • Biggest Galaxies: Super Giant Elliptical= 3 million Light years Smallest Galaxies: DwarfElliptical= 1000 Light years
Spiral galaxy- It is a flatten disc with spiral arms. • There is a galactic bulge in the center that is thick and bright. • Two or more arms wind out from the center of the galaxy. • The Milky Way is a spiral galaxy.
The Andromeda galaxy is our nearest neighboring galaxy. It is a spiral galaxy. Hubble telescope has revealed that it has 2 nuclei which means at one point it has eaten a smaller galaxy
2. Barred spirals- they differ from spiral because of an elongated bar of matter that the arms extend from
The bar in this galaxy extends 150,000 light years across the center. The light we see from this galaxy took 75 million light years to reach Earth…left at the time of the dinosaurs
3. Elliptical galaxy- Has no spiral arms or shape. They range in shape from elongated to circular. Some contain trillion of stars.
Sombrero- famous ellipitical galaxy-it is shaped like a hat…because of its shape, some scientist think it has a black hole in the middle
4. Irregular galaxies- very young galaxies which lack regular structure.
Obj. 3: Describe Galaxy clusters and Super clusters Galaxy cluster- A group of galaxies held together by gravity We belong to the local group cluster Super cluster- a cluster of galaxy cluster