Astronomy Term One

Question 1

Star

Answer 1

A large, glowing ball of gas that generates energy through nuclear fusion in its core

Question 2

Planet

Answer 2

An object that;
- Orbits a star
- Is massive enough for its own gravity to give it a nearly round shape
- Has cleared the neighbourhood around its orbit
Made of rock, ice or gas

Question 3

Solar System

Answer 3

A star and all the objects that orbit it

Question 4

Galaxy

Answer 4

A great island of stars in space, containing billions of stars, all held together by gravity and orbiting a common centre; nearest galaxy is Andromeda and is 2.5x10^6 ly away

Question 5

Nebula

Answer 5

An interstellar cloud of gas and/or dust

Question 6

Light-Year

Answer 6

The distance light can travel in one year, which is 9.46 trillion km. Light takes one second from the moon; eight minutes from the sun; galaxy is over 100 ly across

Question 7

Thousand

Answer 7

Kilo; 1,000

Earth’s distance from the sun is 150 million km; 1.5x10^8km

Question 8

Million

Answer 8

Mega; 1,000,000

Question 9

Billion

Answer 9

Giga; 1,000,000,000

Question 10

Trillion

Answer 10

Tera; 1,000,000,000,000

Question 11

Astronomical Unit

Answer 11

The average distance of Earth from the Sun, which is 150 million km

Question 12

The Big Bang

Answer 12

14 billion years ago

Question 13

Cosmic Calendar

Answer 13

• Big Bang occurred Jan 1st
• Globular clusters were the first thing to form (M80) on February 1st*
• Galaxies grew by colliding March 2nd
• Formation and destruction of stars in June
• Solar system began September 3*
• Oldest known evidence of life on Earth September 22 in West Greenland (3.85 billion years ago)*
• December 17th illustrates Cambrian explosion
• December 26th is dinosaurs and they died December 30th
• December 31st 9pm is our oldest relatives, 11:58 is me*

Question 14

Horizon

Answer 14

Boundary between Earth and Sky

Question 15

Zenith

Answer 15

Point directly overhead

Question 16

Meridian

Answer 16

Imaginary half circle from the horizon due south, through the zenith to the horizon, due north

Question 17

Altitude

Answer 17

Angular distance between the horizon and an object in the sky

Question 18

Constellation

Answer 18

A region of the sky; 88 official constellations cover the celestial sphere

Question 19

Angular Distance

Answer 19

A measure of the angle formed by extending imaginary lines outward from our eyes to span an object or the space between two objects

Question 20

Ecliptic

Answer 20

The Sun’s apparent annual path among the constellations

Question 21

Celestial Sphere

Answer 21

Imaginary sphere on which objects in the sky appear to reside when observed from Earth

Question 22

North Celestial Pole

Answer 22

Directly over Earths north pole

Question 23

South Celestial Pole

Answer 23

Directly over Earths south pole

Question 24

Celestial Equator

Answer 24

Projection of the Earths equator into space making a complete circle

Question 25

Zodiac

Answer 25

Constellations on the celestial sphere through which the ecliptic passes; tradition places twelve but there is officially thirteen (Ophiuchus)

Question 26

June Solstice

Answer 26

June 21; Northern hemisphere is tipped toward the sun; longest day and highest midday sun

Question 27

December Solstice

Answer 27

December 21; Northern hemisphere is tipped away from the sun; shortest day and lowest midday sun

Question 28

Vernal Equinox

Answer 28

March 21; Equal day and night; Northern hemisphere moves from being tipped away to toward the sun

Question 29

Automnal Equinox

Answer 29

September 22; Equal day and night; Northern hemisphere moves from being tipped toward to away from the sun

Question 30

Why Do We Have Seasons?

Answer 30

Due to the Earth’s axis tilt at 23.5 degrees

Question 31

Waning Moon

Answer 31

The set of phases in which less and less of the visible face of the Moon is illuminated; the phases that come after full moon but before new moon

Question 32

Waxing Moon

Answer 32

The set of phases in which more and more of the visible face of the Moon is illuminated; the phases that come after a new moon but before a full moon