Light Intensity / arbitrary units What does this graph show? Light Intensity / arbitrary units Time / min

Eclipses

Solar eclipse Taken with a camera filter NEVER look directly at the Sun, even to observe an eclipse. Use a pin-hole camera instead!

Solar System Data Questions Diameters Sun = 1392 000 km Moon = 3474 km Distance away from Earth Sun = 150 000 000 km Moon = 385 000 km Questions How many times larger is the Sun’s diameter compared with the Moon’s diameter? How many times further away from the Earth is the Sun compared with the Moon? What can we say about the sizes of the Sun and Moon in the sky?

Copy and Complete The Sun is about ___ times wider than the Moon. The Sun is also about _____ times further away from the Earth than the Moon. This means the Sun and the Moon look almost exactly _________in the sky as each other. If this was not the case, eclipses would not be possible.

An eclipse is actually very simple

Solar Eclipse

However…

Secondly However… The Moon’s orbit is not perfectly circular but an ellipse. This is like a slightly flattened circle.

Why don’t eclipses occur all the time? The Moon does not orbit around the Earth’s equator but at an angle. This makes it uncommon for the Moon-Earth-Sun to line up perfectly for an eclipse.  The moons elliptic orbit means that the umbra often doesn’t fall on the Earth’s surface and therefore eclipses don’t happen. Partial eclipses are still very common though

Partial Eclipses

1999 total eclipse

2015 total eclipse

Upcoming Solar eclipses 23rd September 2090 – total eclipse for much of England and Wales How old will you be when these occur?

Lunar Eclipse Much more common, but a bit less spectacular !

Lunar Eclipse A lunar eclipse occurs when the ____ passes behind the ____ so that the _____ blocks the Sun's rays from striking the ____. This can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the _____ in the middle. Hence, a lunar eclipse can only occur the night of a ____ moon. Often the moon will appear red because the Earth’s atmosphere bends the red light and scatters the blue.