Galaxy Stuff
Our Sun, called Sol, is of about (14) _400,000,000,000_ stars in our galaxy. Our galaxy, which is named the (15) _Milky Way_ galaxy, is one of about (16)_400,000,000,000_ galaxies is the Universe. The Milky Way is a (17) _Spiral_ type of galaxy, and our Sun is near the end of one of the spiral arms, but not at the (18) _Tip_ of it.
A galaxy that has symmetry, and can have a shape ranging from a spherical ball to a cigar, is called a (19) _Elliptical_ galaxy. The third type of galaxy, which has no regular shape, is a (20) _Irregular_ galaxy. The best known are the Large and Small _(21)_Magellan_ Clouds. They are actually galaxies, not clouds, and were named after (22)_Ferdinan_ Magellan. Galaxies are held together, not by black holes, but by exotic matter called (23) _Dark Matter__. We only know it is there, because it has gravity.
Groups of galaxies, called (24) _Galaxy Clusters_ may contain a few, or many thousands of galaxies. We belong to the galaxy cluster called the (25) _Local Group, which contains only 14 galaxies. The closest galaxy is (26) __Andromeda__ and it has its “sights” set upon us. It will crash into us in a few hundred million years.
Expansion
The (1) _Doppler_ effect is when the wavelength of energy is shortened or lengthened, because of the (2) __Movement_ of the energy source. Although its effect upon sound is obvious, it is also a factor in the (3) _Electromagnetic_ spectrum, or light. Lines of emission, which should remain PERFECTLY constant, appear to be moved to the wavelengths of the longer (4) __Red_ color when stars and galaxies move away from Earth at great speed. The emission lines would be moved to the (5) _Blue_ color if the stars and galaxies were moving towards Earth. Careful measurements show that all stars are moved towards the (6) _Red_ colors. This is called (7) _Red Shift__, and it implies that everything is moving away from us.
Hubble’s law states, and shows, that the farthest away galaxies are moving away the fastest, and nearby galaxies are moving away more (8) Slowly_. Using this law, we can determine how far away something is, by examining its (9) __Red Shift_ (number 7 above). Just because something is moving away, it does not say WHY it is moving away.
Big Bang.
The Universe started out as a very heavy, but very small, point of matter, about (1) _14 Billion_ years ago. It was about the size of a (2) _Proton_. It did, however, have size and mass. It was also very hot, so it was giving off radiation in the (3) _Gamma_ part of the electromagnetic spectrum. The Universe was expanding, so it also (4) _Cooled_ off, and the electromagnetic radiation began to lose energy as well. The radiation fell to the x-ray, then the (5) _Ultra Violet_, then to visible, then to (6) _Infra Red_, then to infrared, then to microwave, and then to (7) _Radio_. This is the best, best evidence of the big bang theory.
End Game
Some believe that (1) _Gravity_ will finally pull the Universe back together, and it will end in a big crunch. Most believe that an exotic force called (2) _Dark Energy_ will make it expand at a faster and faster rate, until it experiences an end of times, called
(3) _Thermal Death_. This is when the universe is so cold, and things have disconnected so much, that time and distance is meaningless. Mr. Monroe expects an end in ice, but would hope for fire.
1. Who discovered the red-shift of distant galaxies?
a. Drakeb. Winstonc. Hubbled. Webb
2. Disklike galaxies with spiral arms are divided into which of the following two subclasses?
a. normal spirals and flat spirals b. flat spirals and barred spirals
c. normal spirals and barred spirals d. loose spirals and flat spirals
3. Galaxies that are not flattened into disks and do not have spiral arms are called
a. dwarf galaxies. b. elliptical galaxies. c. barred elliptical galaxies. d. nebular galaxies.
4. Galaxies that do not fit into the spiral or elliptical classifications are called
a. dwarf galaxies. b. Hubble galaxies. c. barred galaxies. d. irregular galaxies.
For each statement, write true or false.
5. Most galaxies are spread evenly throughout the universe. _False_
6. The Milky Way belongs to a small cluster of galaxies called the Local Group. _True_
7. The Milky Way and the Andromeda Galaxy are similar in size. _False_
8. Faraway galaxies are blue-shifted. _False_
9. Studies of clusters of galaxies provide astronomers with the strongest evidencethat most of the matter in the universe is visible and accounted for. _False__
10. What forces will determine the fate of the Universe?
a. gravity, electromagnetic, dark energyb. dark energy, dark matter, gravity
c. dark matter, dark energy, electromagneticd. strong nuclear, gravity, electromagnetic
11. All of the possible outcomes for the universe are based on the premise that the rateof expansion has
a. remained the same since the beginning of the universe. b. slowed down.
c. increased since the beginning of the universe. d. doubled since the beginning of the universe.
12. The total amount of matter in the universe is doing what?
a. growing. b. decreasing. c. remaining the same. d. becoming critical.
13. Observations of visible galaxies reveal a(n)
a. red-shift b. blue-shift c. aliens d. no movement
14. Evidence suggests that the universe contains a great amount of
a. visible matter. b. invisible matter. c. mystery matter. d. dark matter.
15. By measuring redshifts of the most remote galaxies, it is possible for astronomers to
determine the
a. Doppler shifts. b. expansion rate of long ago.
c. absolute magnitudes. d. apparent magnitudes.
16. The universe began as a fluctuation in a vacuum and expanded very rapidly for a
fraction of a second, according to the
a. inflationary universe model.b. deceleration model.
c. steady-state model. d. flat universe model.
17. When the rate of expansion of the universe is known, it is possible to calculate the
a. date the universe will end. b. distance to each galaxy.
c. shape of the universe. d. age of the universe.