Earth and Space: Astronomy

Question 1

What does HR stand for in the HR diagram?

Answer 1

Hertzsprung-Russell

Question 2

What two values does the HR diagram compare?

Answer 2

Luminosity and temperature

Question 3

A star that is very bright and hot would be found in what part of the HR diagram?

Answer 3

Upper left corner (main sequence)

Question 4

A star that is dim and somewhat hot would be found in what part of the HR diagram?

Answer 4

Bottom left corner (white dwarves)

Question 5

A star that is very bright and cool would be found in what part of the HR diagram?

Answer 5

Upper right corner (supergiants and giants)

Question 6

A star that is dim and cool would be found in what part of the HR diagram?

Answer 6

Bottom right corner (main sequence)

Question 7

Most stars are classified under what system?

Answer 7

Morgan-Keenan system (MK)

Question 8

The Morgan-Keenan system classifies stars by letters and numbers, which are?

Answer 8

O, B, A, F, G, K, M (O being hottest and M being coolest).

0 - 9 (0 being hottest and 9 being coolest).

Question 9

In the MK system, Roman numerals indicate what?

Answer 9

Luminosity

Question 10

Our sun has the spectral classification of what?

Answer 10

G2V

Question 11

Several new classifications have been added to the MK system. What are some of these?

Answer 11

Class L (very red dwarf), Class T (brown dwarfs with methane in their emission spectra), Class Y (brown dwarfs with ammonia in their emission spectra), Class C (carbon star).

Question 12

What is found on the y-axis of the HR diagram?

Answer 12

Luminosity

Question 13

What is found on the x-axis of the HR diagram?

Answer 13

Temperature

Question 14

What are Kepler’s three laws of planetary motion?

Answer 14

1. All planets move around the sun in elliptical orbits, with the sun as one of the foci.
2. A radius vector joining any planet to the Sun sweeps out equal areas in equal lengths of time.
3. The squares of the sidereal periods (of revolution) of the planets are directly proportional to the cubes of their mean distances from the Sun.

Question 15

What is the brightest constellation?

Answer 15

Crux (or The Southern Cross)

Question 16

Which constellation has the largest number of visible stars?

Answer 16

Centaurus

Question 17

The Big Dipper and the Little Dipper are not constellations; they are _________.

Answer 17

Asterisms (groups of stars within a constellation, in this case Ursa Major and Ursa Minor).

Question 18

The brightest star in the sky is _________, found in the ________ constellation.

Answer 18

Sirius, Canis Major

Question 19

What northern constellation appears to circle Polaris and straddle the Milky Way?

Answer 19

Cassiopeia

Question 20

Which northern constellation named after a famous Greek king never dips below the horizon (circumpolar)?

Answer 20

Cepheus

Question 21

Which southern constellation is found on Australia’s flag and surrounded by Centaurus on three sides?

Answer 21

Crux (The Southern Cross)

Question 22

What is the scientific name for The Swan northern constellation?

Answer 22

Cygnus. Also colloquially referred to as The Northern Cross.

Question 23

The stars Castor and Pollux are found in what constellation?

Answer 23

Gemini.

Question 24

The twelve Zodiac constellations are unique how?

Answer 24

They are located on the ecliptic.

Question 25

What constellation contains Vega, the 5th brightest star in the sky?

Answer 25

Lyra (The Lyre) (northern constellation).

Question 26

The three brightest stars in the northern constellation Orion are what?

Answer 26

Rigel, Betelgeuse, and Bellatrix. Betelgeuse is the left shoulder, Bellatrix is the right shoulder, and Rigel is his right foot.

Question 27

What is a Barlow Lens?

Answer 27

A lens that’s placed into the focusing tube to effectively double or triple a telescope’s focal length and, in turn, the magnification of any eyepiece used with it.

Question 28

Describe a compound telescope.

Answer 28

A telescope with a mirror in the back and a lens in the front.

Question 29

A system of two stars orbiting each other is called a what?

Answer 29

Binary star

Question 30

Define declination.

Answer 30

The celestial equivalent of latitude, denoting how far (in degrees) an object in the sky lies north or south of the celestial equator.

Question 31

What is the ecliptic?

Answer 31

The path among the stars traced by the Sun throughout the year. The Moon and planets never stray far from the ecliptic.

Question 32

Define inclination.

Answer 32

The angle between the plane of an orbit and a reference plane. For example, NASA satellites typically have orbits inclined 28° to Earth’s equator.

Question 33

The Moon tips slightly from week to week, caused by the Moon's inclination and elliptical shape of orbit. This phenomenon is called what?

Answer 33

Libration

Question 34

What is an occultation?

Answer 34

The moon or a planet passing in front of a more distant planet or star.

Question 35

What is The Terminator?

Answer 35

The dividing line between dark and light sides of the Moon. (Disappointing answer, but it's true.)