How Big Is the Moon and
Sun?
Whitchurch High School
Year 8

Earth to the Moon
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The Moon is 384,403 kilometres
(238,857 miles) distant from the
Earth!
Its diameter is 3,476 kilometres
(2,160 miles).
Both the rotation of the Moon and its revolution around Earth takes 27 days, 7 hours, and 43 minutes.
The Moon’s orbit is not perfectly circular.
So the distance is an average!

How we carried out our experiment!

Moon Distance Experiment
Card
Diameter
(m)
0.040
Average
Distance to card (m)
4.27
Average
Distance to
Moon (m)
Diameter of Moon
(m)
384,000,000 3,600,000
0.050
0.060
5.39
6.68
384,000,000 3,560,000
384,000,000 3,450,000

Averages

The average diameter of the moon is
3,536,667metres

The Distance to the Moon is
384,000,000 metres!

How to do the ball experiment
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1 large ball
1 small ball
A ruler
Paper and Pen
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Place your measuring stick with the 0 edge on the side of the table
Then place the large ball at the other end of the meter stick
Place the small ball in front of the large ball at the point where the small ball eclipses the large ball from eye level
Look at the end of the measuring stick and record how far the small ball was away from the big ball.

BALL 2
EYE
BALL 1
B
A
X
Y
Z
KEY (NOTE MEASUREMENTS ALL IN cm)
A=BALL 1 DIAMETER B=BALL 2 DIAMETER
X=DIST TO BALL 1 Y=DIST TO BALL 2

A
(cm)
3.5
our results
B
(cm)
Z
(cm)
X
(cm)
9.5
50.0
17.9
B/A
2.7
Z/X
2.8
3.5
9 .5
100.0
37.0
2.7
2.7
3.5
3.5
9.5
9.5
150.0
200.0
60.0
2.7
76.5
2.7
2.5
2.6

From our results we have concluded that :
The ratio of the two distances and the ratio of the two diameters is the same at about 2.7
B/A = Z/X
So this means the method we just used to measure the diameter of the Moon is valid.

BY: Thomas Pacey and
Hugo Vine

What is the ‘Sea of Crisis’
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The Sea of Crisis is a crater/sea on the moon
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It looks like this:
This is a picture we took of the Sea of Crisis. We took it by placing a web-cam on the back of a telescope and videoed our findings. We used a computer program to stack up the frames and come out with a brilliant picture like this.
The Sea of
Crisis

Method
1. We cut a semicircular hole in a piece of cardboard that measured 1cm in diameter.
2. We then stuck this up.
3. We then slowly stepped back until the Sea of Crisis fitted into the hole.
4. We measured the distance from us to the cardboard
5. We did the experiment four times over and took an average result
6. We then used the other groups results to work out the approx size of the Sea of Crisis

The Results
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(X) The diameter of the hole in the cardboard, 0.01m (1cm)
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(Y) The diameter of the Sea of Crisis in metres
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(A) The average distance from us to the cardboard semicircle was 7.00m
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(B) The distance from the Moon to the
Earth, 384,000,000m

The Answer!
B/A = Y/X ,
This is a ratio standing for distance from earth to moon divided by the distance from us to cardboard is equivalent to the diameter of the Sea of Crisis divided by the size of the semicircle in the cardboard.
The diameter of the Sea of Crisis = B / A x
X = Y
The diameter is 550,000m
( Y ) – this is to 2 significant figures

Conclusion
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Using ratios we calculated the diameter of the Sea of Crisis.
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We discovered that the diameter of the Sea of Crisis is 550,000m
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We used the distance from Earth to Sun -
384,000,000m
End

The Pinhole Camera
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We used a pinhole camera to take measurements of the sun.

A pinhole projector is a box that has a black surface on 1 side, there is a hole a hole in the middle of the black surface. On the other side there is a translucent surface.

Object
Hole
This is a pinhole camera
Image on screen

The Equation
Diameter of the sun = height of sun image
Sun to pinhole image to pinhole

The Numbers Bit
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Camera 1
Measurements:-
Height of image:- 0.2cm
Distance from pinhole:- 16.7cm
Distance to Sun:-1.496x10 8 km

The Answer
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0.2cm x 1.496x10
8 km
16.7cm
=1.8x10
6 km =diameter of sun

The Numbers bit continued
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Camera 2
Measurements:-
Height of Image:- 0.1cm
Distance from Pinhole:-14.0cm
Distance to Sun:-1.5x10 8 km

The Answer
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0.1cm x 1.496x10
8 km
14.0cm
Diameter of Sun:-1.1x10 6 km

The Average Size of the Sun
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1.8x10
6 km+1.1x10
6 km=1.45x10
6 km
2

The Actual Answer
The Sun diameter is
1,391,980 km
Reference GCSE Astronomy