October's full moon won't be just any full moon, as the penumbral lunar eclipse will feature the Earth's shadow (also called the penumbra) on the moon. Viewers should note that only a portion of the Earth's shadow will fall across the moon and as such, there will be a slight dimming on the moon on the lower half. This is different from a total eclipse, during which the moon is darkened completely. "A Penumbral lunar eclipse is when the Moon passes through the "faint" penumbral part of the Earth's shadow - you can expect to see a notable darkening/reddening of the Moon as it passes through the shadow," writes PlanetSave.com about the penumbral lunar eclipse. "The red tint that the Moon possesses during such eclipses is due to the fact that as the Sun's light is filtered through the Earth's atmosphere much of the "blue light" is eliminated, leaving only the reddish hues."
Astronomers have estimated that the deepest penumbral lunar eclipse will take place at 7:50 PM ET on Friday, Oct. 18. Those living in the East Coast of North America and South America should be able to easily spot the eclipse, but the best views will be seen from Europe, Africa and the Middle East. Those living in the latter three regions can expect to observe the penumbral lunar eclipse overnight with bright full moon from 9:51 PM and 1:50 AM GMT. Those who live on the West Coast of North America and South America will not be able to spot the penumbral lunar eclipse, as it will be taking place during daylight hours on the West. As for the next lunar eclipse, it won't be taking place until April 2014 in the annual solar eclipse.
Curious about what exactly causes a lunar eclipse? It takes place when sunlight cannot reach the moon because the Earth's shadow blocks it. There are three different types-total, partial and penumbral-and they vary based on how much of the Earth's shadow falls on the moon. For example, a partial eclipse is when a small portion of the Earth's shadow on the moon's surface, while the penumbral eclipse involves a less dramatic shadow. "Unusual shading on the southern half of the moon should be fairly plain," Sky and Telescope's Alan MacRobert wrote on Sunday. "Look for the penumbral shadow to move from (celestial) east to west across the disc. You might be able to detect lesser traces of penumbral shading for about 45 minutes before and after mid-eclipse."