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Flashcards in P7 - new cards Deck (120)
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1

What is a year?

The time it takes the Earth to complete one orbit of the sun.

The Earth takes 365.25 days to complete one orbit

2

What is the tilt of the moons orbit round the earth compared to the orbit of the earth around the sun?

About 5 degrees.

3

What is the position of the moon during the various phases? 

4

What does the earth spin around?

An imaginary line called the axis.

5

What is the angle of the axis of the earth to the plane of the planetary disk?

6

Why is the sidereal day shorter than 24hrs? 

7

Why do we see different constellations in summer and in winter?

The earth moves around the sun, so we are facing in a different direction at night.

8

Which way does the moon APPEAR to move, seen from earth? 

East to West

9

Which way does the moon ACTUALLY orbit the earth?

From west to east, it actually moves the opposite way to what we see.

10

What is the effect of the moons orbit from west to east on the length of time that it takes for the moon to be in the same place overhead?

It is longer than a day, it is 24h 49mins.

11

What do we see happening to the position of the moon over a month? 

It appears to move "back" slightly every night.

12

What is meant by retrograde motion? 

A planet going the "wrong" way, moving west to east rather than the normal east to west.

13

Draw a picture to explain retrograde motion

14

Explain retrograde motion in words.

  • The nearer to the star a planet is, the faster it moves.
  • Earth therefore moves faster than eg mars.
  • We are therefore catching up with mars, and leaving it behind.
  • As we do so our angle of view changes against the background of the stars are the planet therefore appears to move backwards.

15

Phases of the moon - draw a picture to explain the phases of the moon.

16

Draw a picture of a solar eclipse. Explain the umbra and the penumbra.

17

Draw a picture of a lunar eclipse. What phase of the moon does an eclipse happen in? 

18

Why are lunar eclipses more common than solar eclipses?

The earth's shadow is bigger than the moons shadow.

19

Why are eclipses rare? Draw a picture to demonstrate.

20

How are the coordinates of a star given? 

The angle along the direction of the equator, and the angle along the line connecting the two poles. 

21

What does light travel as?

Waves

22

What is the substance that light travels through called?

The medium

23

What does the speed of light depend on?

The medium

24

What happens to the frequency of a wave when it changes medium?

It remains constant

25

What happens to the speed of a wave as it changes medium?

It changes

26

If the speed of the wave changes, and the frequency remains constant, what happens to the wavelength? 

It has to change.

27

What do we call a change of wave direction as it goes from one medium to another? 

Refraction

28

Draw a picture of refraction

29

What type of lens does a refracting telescope use?

Convex lenses.

30

What happens to parallel rays of lights that enter a convex lens? 

They converge and come to a point at the focus.