Chapter 1 Vocab

Question 1

Solar System (or Star System)

Answer 1

A star (sometimes more than one star) and all the objects that orbit it

Question 2

Milky Way Galaxy

Answer 2

Used both as the name of our galaxy and to refer to the band of light we see in the sky when we look into the plane of the Milky Way Galaxy

Question 3

Galaxy

Answer 3

A great island of stars in space, containing millions, billions, or even trillions of stars, all held together by gravity and orbiting a common center

Question 4

Local Group

Answer 4

The group of about 40 galaxies to which the Milky Way Galaxy belongs

Question 5

Superclusters

Answer 5

The largest known structures in the universe, consisting of many clusters of galaxies, and individual galaxies, and individual galaxies

Question 6

Universe

Answer 6

The sum total of all matter and energy

Question 7

Astronomical Unit (AU)

Answer 7

The average distance (semimajor axis) of Earth from the Sun, which is about 150 million km

Question 8

Light-year (ly)

Answer 8

The distance that light can travel in 1 year, which is 9.46 trillion km

Question 9

Observable Universe

Answer 9

The portion of the entire universe that, at least in principle, can be seen from Earth

Question 10

Big Bang

Answer 10

The name given to the event thought to mark the birth of the universe

Question 11

Nuclear Fusion

Answer 11

The process in which two (or more) smaller nuclei slam together and make one larger nucleus

Question 12

Orbit

Answer 12

The path followed by a celestial body because of gravity: an orbit may be bound (elliptical) or unbound (parabolic or hyperbolic)

Question 13

Rotation

Answer 13

The spinning of an object around its axis

Question 14

Ecliptic Plane

Answer 14

The plane of Earth’s orbit around the Sun

Question 15

Axis Tilt of a planet in our Solar System)

Answer 15

The amount by which a planet’s axis is tilted with respect to a line perpendicular to the ecliptic plane