2. An interstellar cloud of gas known as an H-II region is mainly composed of what?
3. What celestial object is known as the morning star or the evening star depending on when it is seen in the sky?
4. Which planet of the Solar System is accompanied by two moons named for the Greek gods of fear and terror?
5. On what kind of diagram are stars plotted according to their surface temperature and luminosity?
6. A common problem with refracting telescopes is a fringe of false color around the image, caused by the inability of a large lens to refract all colors of the spectrum to a common focus. This is known as ______.
7. For a body in orbit around the Sun, the point in its orbit which is furthest from the Sun is called __________.
8. The first constellation in the Zodiac is _______.
9. The brightest star in the constellation Taurus the Bull is the red giant Alpha Tauri, better known as ______.
10. A solar eclipse isn't always total. If the Moon is far enough from the Earth, its umbra fails to completely obscure the Sun, so that a ring of sunlight appears around the Moon. This is a called an ______.
11. The brightness of a star as it is seen from Earth is measured on a logarithmic scale, and known as its _______.
12. Right next to Pegasus is this constellation named after a mythical princess who was rescued by Perseus. Within its boundaries is the nearest spiral galaxy to the Milky Way. What is it?
13. Aristarchus of Samos in 280 BCE was one of the earliest philosophers to suggest which model of the solar system?
14. A black hole is always surrounded by an ___________.
15. The Pinwheel Galaxy, a spiral galaxy located in the constellation Ursa Major, is also known as M101. What does the "M" stand for?
16. What is the name for the point when an object in orbit around the Earth comes its closest to