April 2015 Total Lunar Eclipse
By Hannah Kavanaugh
3.30.15 – Also known as a “Blood Moon”, a total lunar eclipse will occur on average, once a year, but seeing them from your location is by no means a guarantee. Though rare, sometimes a “lunar tetrad” will occur, where four lunar eclipses happen in a relatively short amount of time. Each are six months apart and several full moons will happen in between the total eclipses.
So what is a lunar eclipse anyway, let alone a total lunar eclipse? A lunar eclipse is when the Earth comes in between the sun and the moon, and the Earth’s shadow is cast onto the full moon. Most of the time, the three bodies wont line up perfectly, which can cause a partial lunar eclipse, but about once a year, the three line up and the Earth’s shadow will fully cover the moon. This is different from a solar eclipse where the moon casts a shadow on the Earth and temporarily blocks out the sun.
Many people may have seen images of lunar eclipses where the moon is big and bright and rust colored. Interestingly enough, this only occurs during a total lunar eclipse, and only when the eclipse reaches totality. Until that point, the moon looks like sections of it are missing. As the Earth’s shadow covers the moon, less and less of the moon is visible, until the moon is entirely covered and the moon begins to glow red or orange. This coloring is caused by light passing through the Earth’s atmosphere.
The Earth’s atmosphere is filled with elements that scatter the light from the sun. This scattering causes our blue sky on Earth. During a lunar eclipse, the moon appears red because red light is scattered least. This way it can pass through the Earth’s atmosphere and light up the moon (EarthSky.org). The color can vary from eclipse to eclipse based on the constant changes going on in Earth’s atmosphere. It may be dustier one day, higher humidity or temperature the next.
Coming up soon is a rare “Blood Moon”, the third in this lunar tetrad. So if you go out early in the morning on April 4th you might be able to catch the very beginning of the eclipse before it sets in Maine.