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Physics 21st Century > The Earth in the Universe > Flashcards

Flashcards in The Earth in the Universe Deck (87)
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1

What is at the centre of the solar system

A star called the sun

2

How many planets in the solar system?

8

3

Make up a way of remembering the planets MVEMJSUN

eg My Vicious Earthworm Might Just Swallow Us Now

4

What is the planet nearest to the sun?

Mercury

5

Name the planets in order, starting at the sun

Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune

6

What is a moon?

A ball of rock in an orbit around a planet

7

What is a comet?

A small lump of ice and rock in a very elongated orbit around the sun

8

What is an asteroid?

Irregular lumps of rock, mainly found in orbit around the sun in a belt between Mars and Jupiter

9

Where are the dwarf planets?

Beyond Neptune (though Pluto can go inside the orbit of Neptune)

10

How much of the mass of the solar system is in the sun?

99%

11

Which is the heaviest planet?

Jupiter

12

Earth is larger than?

Venus, Mars, Mercury

13

What is the Milky Way?

Our galaxy

14

What is a galaxy?

A group of stars

15

What is the speed of light?

3x10 ^ 5 km/s.

16

What is a light year?

The distance light travels in a year - about 9.5 million million km.

17

What evidence can we collect from distant stars?

Only the radiation they emit.

18

What is the difference between brightness and relative brightness?

Brightness is what the star is giving out, relative brightness is what we see from earth.

19

What happens to relative brightness as stars are further away?

It reduces.

20

How can relative brightness be used to calculate the distance of stars?

The difference of relative brightness can be used to calculate the difference between two similar stars

21

What are the problems of using relative brightness to calculate the distance to a star?

It is based on the assumption that the same type of star has a constant brightness. It is based on an estimate of the distance to one of the stars. Brightness can be affected by many things on earth, eg light pollution, dust.

22

Where are telescopes placed to avoid the distortion of earth's atmosphere?

Space

23

How else can the distance of a star be measured?

Parallax

24

How is parallax used?

The earth moves in orbit, so the star is observed 6 months apart, and it appears to move relative to stars that are further away. The amount of movement can be used to calculate the distance.

25

What are the problems of using parallax?

Only close stars appear to move as the earth orbit is small compared to interstellar distances.

26

How does the sun generate energy?

Nuclear fusion.

27

What nuclear fusion takes place in the sun?

4 hydrogen nuclei are fused to form helium

28

What elements are believed to have been present in the early universe?

Only hydrogen

29

Where do all the elements from hydrogen up to iron come from?

They have been produced by nuclear fusion in stars, then spread through the universe by stellar explosions.

30

Where are the elements heavier than iron made?

In a supernova