* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Astronomy Unit 4 Galaxies
Perseus (constellation) wikipedia , lookup
Shape of the universe wikipedia , lookup
Aries (constellation) wikipedia , lookup
Drake equation wikipedia , lookup
History of astronomy wikipedia , lookup
Rare Earth hypothesis wikipedia , lookup
Dark matter wikipedia , lookup
Dark energy wikipedia , lookup
Fine-tuned Universe wikipedia , lookup
Fermi paradox wikipedia , lookup
International Ultraviolet Explorer wikipedia , lookup
Outer space wikipedia , lookup
Space Interferometry Mission wikipedia , lookup
Gamma-ray burst wikipedia , lookup
Non-standard cosmology wikipedia , lookup
Expansion of the universe wikipedia , lookup
Corvus (constellation) wikipedia , lookup
Andromeda Galaxy wikipedia , lookup
Physical cosmology wikipedia , lookup
Malmquist bias wikipedia , lookup
Hubble's law wikipedia , lookup
Modified Newtonian dynamics wikipedia , lookup
Chronology of the universe wikipedia , lookup
Stellar kinematics wikipedia , lookup
Lambda-CDM model wikipedia , lookup
Observational astronomy wikipedia , lookup
Timeline of astronomy wikipedia , lookup
Star formation wikipedia , lookup
Cosmic distance ladder wikipedia , lookup
High-velocity cloud wikipedia , lookup
Name: __________________________________________ Astronomy Unit 4 Galaxies 1. A collection of millions or billions of stars held together by their gravity. ____________________ 2. Our galaxy. ____________________________ 3. Flattened, circular region our solar system is within. _______________________ 4. Central region of the Milky Way that contains older stars. ___________________ 5. Spherical region of faint stars that surrounds our galaxy. ____________________ 6. First person to estimate the size of our galaxy by counting stars in all directions. ___________________________ 7. This prevents us from seeing the true shape of our galaxy. __________________ 8. These stars are used to estimate the distance to distant parts of our galaxy. _________________________ 9. Variable stars represent which stage in evolution of stars? ___________________ 10. Low mass variable stars. _____________________________ 11. High mass variable stars. _____________________________ 12. Variable stars are used to estimate distance because the period of variability is related to the star’s ______________________. 13. Harlow Shapley discovered the Sun’s true place within our galaxy by measuring variable stars in ________________________ that surround the Milky Way. 14. The Sun is located _________________ from the center of our galaxy with the ______________. 15. The Milky Way takes approximately __________________________ years to revolve once at the Sun’s distance from the center. 16. The closer to the center of the Milky Way, the __________________ the stars revolve around the center. 17. These are used to “see” through the gas and dust that permeates our galaxy. ___________________________ 18. At the center of our galaxy resides a __________________________________ which is a strong radio source called _____________________________. 19. To measure the mass of our galaxy, the _____________________ of stars at the _________________________ regions is measured. 20. The speed of stars in the outer parts of the Milky Way are moving ____________ than they should be implying that there is _______________ mass than can be seen in the Milky Way. 21. This mass that cannot be seen is called __________________________. 22. Galaxies are categorized based on their ________________________ in a scheme called the _________________________________. 23. The four types of galaxies: a. ____________________ b. ____________________ c. ____________________ d. ____________________ 24. The type of galaxy the Milky Way is. _____________________________ 25. Easily seen objects with luminosities that are known and are used to measure distances in the universe are called _______________________________. 26. Galaxies tend to congregate in groups called _____________________________. 27. These groupings of galaxies themselves form larger groupings called __________________________ 28. Measuring the mass of superclusters of galaxies has led to the discovery that 90% of the universe is composed of this. __________________________ 29. Galaxies grow through collisions with other galaxies in a process known as ______________________________________. 30. Edwin Hubble observed the spectra of galaxies and noticed that the farther a galaxy is away from us the ______________ its redshift and the ______________ it is moving away from us. 31. The rate at which a galaxy recedes is directly proportional to its distance is known as this. ___________________________ 32. Hubble’s Law implies that all galaxies are moving _________________ from us and ______________________. 33. Hubble’s Law shows us that the universe is doing this. ____________________ 34. The redshift caused by the expansion of the universe. ______________________ 35. Hubble’s Constant tells astronomers how _______________ the universe is expanding. 36. The approximate age of the universe determined by using Hubble’s Constant. __________________________________ 37. The distribution of galaxies in the universe is not ___________________, but clusters of galaxies lie within structures called ___________________ which surround empty regions called __________________. 38. Galaxies that are brighter than normal are called __________________________ and emit most of their radiation at ________________ wavelengths. 39. The source of energy in active galaxies changes over short periods of time implying they come from regions which are _______________ in size. 40. Explosive activity in active galaxies is often emitted in two large extended regions called __________________________. 41. Quasi-stellar radio sources are better known as _____________________. 42. Quasars show large _________________ which means they are very _________________, so they must be the __________________ objects in the universe. 43. The energy from active galaxies comes from _____________________________ found at the center of these galaxies where gas is ___________________ onto it. 44. Active galaxies represent an _______________ stage in evolution of galaxies from a time when the universe had lots of gas to accrete onto supermassive black holes. 45. Some quasars evolved to form _________________ galaxies which evolved into normal spirals while others evolved into _______________ galaxies which evolved into elliptical galaxies.