A Lunar Eclipse….from the Moon

We have all seen plenty of solar eclipses and lunar eclipses over the last decade. The solar eclipse of course being where the Moon while orbiting around the Earth passes between the Earth and the Sun. We go through a few minutes of darkness while the Moon passes it’s shadow across the earth.

But since the Moon orbits around the Earth once every month, why would we not have a solar eclipse every month? See if you can work that out.

Solar Eclipse seen from the Moon (Click to enlarge)

Of course the lunar eclipse is where the Moon passes behind the Earth so that the Moon blocks the Sun’s light from reaching the Moon… in other words the Moon is in the Earth’s shadow.

Now the lunar eclipse is always much longer than a solar eclipse…… see if you can work out why that is so……

When you are next watching a lunar eclipse, consider this. While you are standing in Sydney watching the Earth’s shadow cross the Moon, think about what the view would be like if you were standing on the Moon and the shadow crossed over the lunar landscape around you.

Surprisingly the area in shadow would not experience total darkness but would be bathed in red light as I have tried to show in the picture above. This is due to the refraction of the Sun’s light in the Earth’s atmosphere before it reaches the Moon.

So when we are experiencing a lunar eclipse where the Moon has to be a full moon, The Moon itself would be experiencing a solar eclipse which is pretty much the opposite view of a lunar eclipse.

Also consider that our Earth-Moon system is unique in our solar system since the angular size of the Sun exactly matches the angular size of the Moon. This means if you put them side by side in the sky they would occupy the same amount of space in the sky.

So during an eclipse, the Full Moon is in the right place and at the right time and will fit perfectly over the Sun. This is not seen elsewhere in our solar system.

~ by sydneystargazers on November 24, 2009.

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