Friday, March 18, 2011

From the Moon to the Sun: Cool Astronomy Events This Weekend!

We have a couple of interesting astronomical events this weekend, from the Moon to the Sun. The Full Moon is Saturday night, rising in the east in Richmond at 7:40 PM.
This will be a rare perigee full moon, meaning that the Moon is at its closest proximity to the earth in its elliptical orbit around us. As a result of literally being closer to the Earth and also being a Full Moon, it will be 14% bigger and 30% brighter than when the Moon is at apogee (farthest away from Earth in its elliptical orbit).

In addition, there is an optical illusion that occurs when the moon is at the horizon: it looks to our eyes to be huge, even though it really isn't (camera photos can prove this illusion by showing the moon is the same size at the horizon as when it's higher aloft)!

(Image above: Lloyd Kaufman & James H. Kaufman)
So this combination of literally being bigger and brighter plus merely appearing to be bigger should lead to a great Full Moon viewing Saturday at sunset. It looks like cloud-cover on Saturday should be moving out of the area by sunset, so hopefully we'll get to see this Full Moon on the eastern horizon as it rises.

Our second astronomical note for this weekend is the Vernal Equinox.
This is the official astronomical start of Spring on Sunday at 7:21 PM EDT.
This is the exact moment when the Sun's most direct rays are over the Earth's Equator. After this, the most direct rays continue to creep northward into the Northern Hemisphere, leading us into our Spring and Summer months until the Autumnal Equinox, when the most direct rays are back over the Equator on their trek southward into the Southern Hemisphere.