4 Types of Galaxies

1. 4 Types of Galaxies Galaxies Test 1

2. 4 Types of Galaxies 1. Spiral 2. Irregular 3. Elliptical 4. Lenticular A galaxy is a group of stars, dust and gas.

3. Spiral Galaxy • The most common type of galaxy is called a "spiral galaxy." • Not surprisingly, spiral galaxies look like spirals, with long arms winding toward a bright bulge at the center. • About 77% of the observed galaxies in the universe are spiral galaxies. • Our own galaxy, the Milky Way, is a typical spiral galaxy

7. Elliptical Galaxies • They are generally round but stretch longer along one axis than along the other. • Elliptical galaxies contain many older stars, up to one trillion, but little dust and other interstellar matter. • The universe's largest known galaxies are giant elliptical galaxies, which may be as much as two million light-years long.

11. Irregular Galaxies • Approximately 3% of galaxies observed cannot be classified as either ellipsoidal or spirals. • These galaxies have little symmetry in their structure and are termed irregular galaxies.

15. Lenticular Galaxy • Lenticular galaxies are disc galaxies (like spiral galaxies) which have used up or lost most of their interstellar matter and therefore have very little ongoing star formation. • As a result, they consist mainly of aging stars and will produce the least amount of stars.

18. CONSTELLATIONS

19. What are Constellations? • Constellations are named patterns of stars. All societies created them. • The classical -- "ancient" -- constellations that populate our sky began in the lands of the middle east thousands of years ago, their origins largely lost to time. • They passed through the hands of the ancient Greeks, who overlaid them with their legends and codified them in story and verse. • There are 88 named constellations

20. Orion If you look about due south around 9 p.m. your local time this week, you may see a familiar sight dominating our winter skies: the Great Hunter or Celestial Warrior, Orion, the most brilliant of the constellations and visible from every inhabited part of the Earth. 

21. Red Supergiant Blue Supergiant

22. The ancient mythological stories of Orion are so many and so confused that it is almost impossible to choose among them. • Probably the best known is the one where he got into trouble for bragging that no game could ever escape him. This annoyed the goddess Hera, who sent a poisonous scorpion (Scorpius) to sting his heel, and Orion subsequently died. • Orion, however, was brought back to life by the great physician, Aesculapius who got his medical secrets from the snakes. But the god Hades, King of the Dead, heard about this miraculous deed and became concerned about the future of his kingdom.  • So he asked Zeus to intervene, and Zeus threw thunderbolts and liquidated both Orion and Aesculapius.  As a precaution, Orion and the Scorpion were placed in opposite parts of the sky so they could never get into further trouble.  

23. Canis Major-Sirius is the brightest star in the sky.

24. Big Dipper- Ursa Major

25. Follow the Drinking Gourd • The American folksong Follow the Drinking Gourd was first published in 1928. The Drinking Gourd song was supposedly used by an Underground Railroad operative to encode escape instructions and a map. These directions then enabled fleeing slaves to make their way north from Mobile, Alabama to the Ohio River and freedom. Taken at face value, the "drinking gourd" refers to the hollowed out gourd used by slaves (and other rural Americans) as a water dipper. But here it is used as a code name for the Big Dipper star formation, which points to Polaris, the Pole Star, and North.

26. Little Dipper- Ursa MinorThe most famous star in Ursa Minor is Polaris, the North Star Polaris-North Star