Topic Twelve Flashcards Preview

Abi Biology 2015 > Topic Twelve > Flashcards

Flashcards in Topic Twelve Deck (25):
1

What is a constellation?

A constellation is a group of stars that is named.

2

Which inventions allowed astronomers to discover new planets?

The telescope, the radio telescope and infrared technology allowed astronomers to do this.

3

What allows us to get more close-up views of space?

Spacecrafts and special instruments allow us to do this.

4

What is a galaxy?

A galaxy is a large collection of stars held together by their natural gravity.

5

What shapes are galaxies?

Galaxies are sometimes spherical shaped, spiral shaped or irregularly shaped.

6

What are 'cities of stars'?

'Cities of stars' are merged galaxies.

7

What is a theory of how galaxies are formed?

One theory is that small lumps of matter clump together to form spiral-shaped galaxies.

8

What are ellipticals?

Ellipticals are formed when smaller galaxies are merged into bigger ones. The stars then wrap around the centre of the galaxy, forming a spherical shape.

9

What are dwarf galaxies?

These are smaller galaxies that have merged together

10

What is dark matter?

Dark matter is matter that does not produce any light, instead it reveals itself through its strong gravitational pull on stars and other objects. 90% of the Milky Way appears to be dark matter.

11

What is our galaxy called?

Our galaxy is called the Milky Way Galaxy.

12

What is the composition of the Milky Way galaxy?

The Milky Way galaxy consists of a thick bulge of stars in the centre with four bright spiral arms and from above it looks like a flat disc.

13

Where is our sun situated in the Milky Way galaxy?

It is located near the edge of one of the spiral arms.

14

How big is the Milky Way galaxy?

It is 100000 light years in diameter and 2000 light years thick

15

What is our closest star?

Our closest star is the sun.

16

What protects us from the harmful rays of the sun?

The ozone layer does this.

17

Which is our nearest star system?

Alpha Centauri is our nearest star system

18

Where is Alpha Centauri?

It is the brighter of the two pointer stars of the Southern Cross. It forms part of the constellation Centaurus.

19

What is the closest planet outside our galaxy that circles a sun?

Alpha Centauri B has an unamed as yet planet circling it.

20

What is the unit of measurement used for distances in space?

Light years.

21

What is a light year?

A light year is the distance that light travels in a year.

22

What was the name of the first galaxy discovered outside our solar system?

It was called the City of Stars.

23

What is the Local Group?

It is a group of about 45 galaxies that surround the Milky Way.

24

What is a merger?

A merger is galaxy that will become part of another galaxy.

25

What is the estimated age of the universe?

The universe is estimated to be 13.7 billion years old.