Chapter 16 Questions.

2, 5, 10, 22, 25

2. The most basic method of calculating stellar differences is stellar parallax, the measure of the slight back-and-forth shift in a nearby star's position due to the orbit of Earth. The closer the star is to Earth, the larger it's apparent motion will be. If the star is very far away from Earth, it's parallax, or movement, will be very slight.

5. The color of a star tells us the temperature that the star is burning. A bright blue star is burning very hot, with surface temperatures above 30,000 K. Yellow stars, such as our own, burn with medium temperature for a star, at about 5000-6000 K on the surface. Red stars are the coolest stars, with surface temperatures less than 3000 K.

10. A star spends the most of it's lifetime in the middle of an HR diagram, as 90% of stars are main-sequence stars, stars that have a normal lifespan. (Our sun is a main-sequence star, falling in the middle of the HR diagram.)

22. The three types of galaxies are; spiral galaxies, elliptical galaxies, and irregular galaxies. Spiral galaxies are usually disk shaped, with more stars near the middle of the galaxy, and have arms or lines of stars extending from the clump of stars in the middle. Elliptical galaxies are the most common, with an elliptical shape, that are nearly spherical. Irregular galaxies lack symmetry, and are more rare, accounting for 10% of known galaxies.

25. We still can see minor microwaves of energy left over from the Big Bang, and from it NASA has even managed to compose a picture of where this energy was distributed in the universe. While the Big Bang theory can never be 'proved' these findings provide significant evidence to support it.