7L.4 The Sun and the Moon
You should already know Outcomes Keywords
You must be careful looking at the Sun. You must never the setting Sun
look directly at it even wearing sunglasses. The Sun is so
bright its light can permanently damage your eyes.
If you observe the Sun and the Moon from the Earth, they appear to
be about the same size. But this is just an illusion. The Sun is actually
400 times bigger than the Moon. If the Sun was the size of a house, the Moon in exactly the same
the Moon would be the size of a mouse. The diameter of the Sun is direction at a different time
over 400 times bigger than that of the Moon. However, the Sun is
nearly 400 times further away from the Earth than the Moon is. The
difference in their sizes is cancelled out by the difference in their
distances from the Earth. They appear to be the same size in the sky. The Sun and the Moon look the same size.
Eclipses
Because the Moon appears to be the same size as the Earth
Sun, it can blot the Sun out if it gets into just the right
position. This happens occasionally when the Moon Sun x
passes between the Sun and the Earth. This is called a
solar eclipse. The Moon casts a shadow on the surface Moon
of the Earth. The part of the Earth where the shadow
falls is dark, even though it is daytime! If you are in x = total eclipse not to scale
the place where the shadow is, the Sun is hidden by An eclipse of the Sun happens when
the Moon. the Earth is in the Moon’s shadow.
There are two parts to the Moon’s shadow. In the very 9
middle is a complete shadow where all of the Sun is 8
blocked out. This is called a total eclipse. This area is 7
usually only a few miles across. Total eclipses are not 6
very common in the UK. The last one was in August
5
1999 in Cornwall.
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Around the edge of the total shadow, there is a part
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shadow where only some of the Sun is blocked out.
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People in this area see a partial eclipse. This area
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stretches for hundreds of miles. When the total eclipse
happened in Cornwall, the partial eclipse could be seen
in Yorkshire.
Nine photos of the stages of a total solar eclipse.
Number 5 shows totality.
Question 1 2 3
130 7L The Solar System and beyond
7L.4 The Sun and the Moon
Eclipses do not happen every lunar month. The orbit of the Moon
around the Earth is at a slight angle compared with the orbit of the
Earth around the Sun. This means that the Earth, Moon and Sun do Moon
Sun
not line up very often.
Solar eclipses do not happen very often over the same place on the
Earth. Between 1724 and 1927, there were no total eclipses visible Earth not to scale
from mainland Britain.
Date Notes
1st August 2008 partial eclipse
4th January 2011 partial eclipse in south-east England
20th March 2015 partial eclipse
11th August 2018 partial eclipse in the north of Scotland
23rd September 2090 total eclipse in Cornwall lasting 2 minutes
and 10 seconds
The solar eclipses visible from the UK in this century.
Question 4
Lunar eclipses
Moon
The second type of eclipse we see from Earth is called
a lunar eclipse. This happens when the Sun, Earth and
Moon line up, with the Earth between the Sun and
Earth
the Moon.
A lunar eclipse happens when the Moon has moved Sun not to scale
into the Earth’s shadow. An eclipse happens when the Moon
is the Earth’s shadow.
You would expect the Moon to disappear completely
because there would be no light reaching it, but this is
not quite what happens. The Earth’s atmosphere bends
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some light from the Sun around to the Moon. This
8
means that the Moon is lit up by a faint glow. If you 7
look at the photograph under the number 5, you can see 6
5
that the Moon is a faint reddish orange colour, a bit like 4
3
copper metal, when the total eclipse happens. 2
1
Again, because the Moon’s orbit is at an angle to
the Earth’s orbit, lunar eclipses do not happen every
month, but they are much more common than solar
eclipses. Sometimes there are several in a year.
Question 5 6 Nine photos of a total lunar eclipse.
7L The Solar System and beyond 131