chapter 1: cosmology

Question 1

geocentric

Answer 1

all heavenly bodies circle around Earth, which is at the
center of the Universe

Question 2

heliocentric

Answer 2

Earth, planets, stars, etc. circle around the sun (but our Sun is not the center of anything beyond our solar system)

Question 3

Star

Answer 3

immense sphere of incandescent gas, mostly Hydrogen
(H) with some Helium (He), held together by gravity. Almost
all stars are orbited by planets that have coalesced from a
disk-shaped “nebula” of gas and dust.

Question 4

Galaxy

Answer 4

immense groupings of stars (100s of billions)

Question 5

Universe

Answer 5

immense grouping of galaxies (100s of billions)

Question 6

where do the elements come from?

Answer 6

• the “Big Bang”: formation of Hydrogen (H) and Helium (He) - simplest elements
• Gravity causes collapse of H/He gas clouds into first stars
• When H/He supplies get low, there are different paths a star can take, including several that involve the explosion of the star in a “supernova.”

Question 7

Why is the solar system made of planets and moons?

Answer 7

Nebular theory of solar system formation

Question 8

supernova

Answer 8

star explode, new elements –> life

Question 9

Moho boundary is due to…

Answer 9

composition
differences between crust and mantle.