Unit 4 Introduction1. How many powers of ten separate the approximate diameter of Earth (North and Central America) from the diameter of our SolarSystem (the orbits of Neptune and Pluto)?a. 62. How many powers of ten separate the diameter of the Solar System and the diameter of the milky way galaxy?a. 83. How much bigger is the Earth than quarks (sub-atomic particles)?a. 1023 times4. What is the name of the nearest large spiral galazy to our own Milky Way in the Local Group?a. The Andromeda Galaxy.Unit 4 Part 1: Galaxy Classification1. Which Galaxy do you come from?a. The Milky Way2. Why is our Galaxy called the Milky Way?a. The term 'Milky Way Galaxy' is derived from the Greek word for milk, and there appeared to be a stream of milk running across the sky.3. What kind of Galaxy is the Milky Way?a. Spiral4. What color of stars are found in the young star clusters in the disk of the Whirlpool galaxy?a. Blue5. Why do hydrogen gas clouds glow red?a. Electromagnetic radiation from nearby stars heats the clouds until they glow red.6. Why are there dark lines in the spiral arms of the Whirlpool Galaxy?a. They are regions of dust that block the light of the stars behind them.7. In what part of spiral galaxies do new stars form?a. In the Spiral Arms8. Why can’t Thomasin find any constellations she recognizes?a. From any position far outside the Solar System, the stars are seen at different angles and fall out of the constellations' traditional shapes.9. What causes the long tail to protrude from this galaxy?a. Tidal forces caused by interaction with another galaxy are drawing the material off.10. Why are the star clusters in the tidal tail blue?a. Blue stars in these newly active star-forming regions far outshine the less massive red stars.11. Compared to spiral galaxies, elliptical galaxies have…a. … les gas, less dust,, and less new star formation12. Among Spiral galaxies, an “SBa” has…a. …. A bar, tight smooth spiral arms, and a large bulge13. What is the difference between an E0 and an E7 galaxy?a. The E7 has an oval shape and the E0 is circular14. What category do astronomers use if a galaxy does not fit into the spiral or elliptical category?a. Irregular15. What happens to the planets in a galaxy when that galaxy collides with another galaxy?a. Nothing, because the spaces between stellar systems in a galaxy is much larger than their size.16. What kind of galaxy will be the final result from the collision of the Milky Way and Andromeda galaxies?a. A large elliptical17. What is the result when gas clouds from both of the colliding galaxies meet?a. The clouds crushing down on each other starts a burst of new star formation18. What are the 3 parts of the spiral galaxy, and which 2 might you see through a telescope?a. Disk, bulge, and halo; would see bulge and disk, and wouldn’t see halo19. What are the “friends” (other types of galaxies close to ours)a. Nearby dwarf galaxies clustered around the spiral galaxy20. How might a nearby neighbor change the shape of this galaxy?a. The merger of two spiral galaxies may give rise to an elliptical galaxy21. What is this galaxy doing that keeps it from being idle?a. Stars are forming in the spiral arms and the disk is rotatingUnit 4 Part 2: Distant Universe, Distant Past1. How far does light travel in 100 years?a. 100 lightyears2. How many galaxies are needed to get a fair sample to determine what fraction are elliptical?a. 35-453. About what percentage of Hubble Deep Field (HDF) galaxies do astronomers find are irregular?a. 70%4. Does the universe look the same in the directions of HDFN and HDFS (fractions of galaxy types statistically similar?)a. Yes5. How old was the universe when light from the most distant galaxies in the Hubble Ultra Deep Field was emitted?a. 800 million years6. What would describe the earliest galaxies?a. They were undergoing rapid changes7. How do tadpole galaxies get their shape?a. They represent merging galaxies8. Why didn’t they see flickering brightness that would show black holes were eating gas from mergers?a. There’s a delay between the merger and time gas and stars flow into the black hole9. How might light be captured?a. Hubble Space Telescope10. Why won’t an object be seen as it is today, if you could go to its location instantly?a. Light has been traveling a large distance through space since it left theobject; we see the object as it was in the past11. What is nature’s speed limit?a. The Speed of Light12. If the objects seen in the past are galaxies, how might they have changed?a. The galaxies were more irregular and patchy in the past than they are at presentUnit 4 Part 3: Implications of the Hubble Deep Field1. Why was it important to have a “boring” patch of sky for the Hubble Deep Field?a. To minimize the number of objects in the view that were local to our own galaxy.2. How many stars are in each galaxy in the Hubble Deep Field?a. From one billion (109) to a hundred billion (1011).3. Why did these astronomers take so many different pictures of the same patch of sky?a. To average over many images and keep only the consistent object details, filtering out random single-exposure events like charged particles from the solar wind.4. How far away is most distant galaxy seen in the Hubble Deep Field?a. A: About twelve billion (1.2x1010) light years.5. How many galaxies are there in the observable universe?a. Fifty to a hundred billion (5x1010 - 1011).6. How many stars are there in the observable universe?a. 100 billion x 10 billion = 1022.7. How tiny a spot is the Hubble Deep Field?a. The size of President Roosevelt's eye on a dime held at arm's length.8. Why does the image show very few stars?a. It was chosen so that bright stars in the Milky Way Galaxy do not interfere with our picture of the distant universe.9. About how many dots are seen in the Hubble Deep Field image, just within that image? What are the dots seen in the Hubble Deep Field?a. 3000 galaxies10. How many galaxies are there in the part of the universe we can observe?a. 50-100 billionUnit 4 Part 4: Quasars and gamma ray bursts1. Where do we observe black holes?a. In orbit around stars in binary systems, in the center of the Milky Way Galaxy, In the centers of elliptical galaxies, and in quasars2. Which are more massive, the black holes in x-ray binaries or those at the centers of galaxies?a. Black holes in the centers of galaxies are more massive3. Which have more massive supermassive black holes, spiral