• Question: what causes an eclipse?

    Asked by yassie to Adam, Catherine, Karen, Leila, Nazim on 19 Mar 2012. This question was also asked by purplebug123.
    • Photo: Adam Stevens

      Adam Stevens answered on 19 Mar 2012:

      There’s two types of eclipse – lunar and solar.

      Lunar eclipses happen because the Earth blocks the moon from the sun’s light. Note this isn’t the same as a new moon, which is just when we can’t see the illuminated side of the moon. What happens in a lunar eclipse is that some light from the sun is refracted through the earth’s atmosphere, just like a prism, making the moon turn red! However, you don’t really get a total eclipse, the moon just dims a bit.

      A solar eclipse is much more impressive. By some quirk of cosmic coincidence the moon is just the right size and in just the right place to totally block the light from the sun. This means it is directly in front of the sun. Not everywhere on the Earth gets eclipsed at the same time as the moon is so small, and it is very rare because the orbit of the moon doesn’t always line up with the sun, but when it happens it totally blocks the light from the main part of the sun, leaving only the corona visible (in fact, the corona was discovered by observations during eclipses)

    • Photo: Leila Battison

      Leila Battison answered on 19 Mar 2012:

      Eclipses of the sun are caused when the moon moves between the Earth and the Sun, and lines up directly in front of it so it blocks all the light coming from it.

      A lunar eclipse happens when the earth passes in front of the moon, so the sunlight that normally reflects off the moon, is blocked.

    • Photo: Karen Masters

      Karen Masters answered on 19 Mar 2012:

      A solar eclipse the name we give for when the Moon gets between the Sun and the Earth – so the Sun’s light gets blocked by the Moon. It’s a funny coincidence that while the Sun is 300 times larger than the Moon it’s also 300 times further away so they appear exactly the same size on the sky. So the Moon can exactly block out the Sun.

      A lunar eclipse is when the Earth gets between the Sun and the Moon. The Moon only shines because it reflects the Sunlight, so when this happens the Moon gets very dark.

    • Photo: Nazim Bharmal

      Nazim Bharmal answered on 19 Mar 2012:

      We are quite lucky that the Moon is the right size and distance from the Earth to be almost the same size as the Sun. So what happens is that the Moon basically gets in the way of the Sun and casts a shadow on the Earth. This can only happen in a one place at a time, for a couple of minutes, and then the light from the Sun returns.

      That is a solar eclipse, and it can happen in reverse too: the Earth just blocks the light from the Sun hitting the moon directly. When that happens, the light reflecting from the moon turns red (because of the light from the Sun that is bent about in the Earth’s atmosphere) and the moon looks reddish-pink in the sky, although it is still quite bright. (Remember that the moon can only reflect light it gets so to see the Moon means there is still light falling onto it and reflecting into our eyes.)