Monday, May 14, 2012

May 20th Annular Solar Eclipse - Time To Get Ready!

If you live in a corridor that stretches between north-central Texas and northern California, then you're in for a very special astronomical treat as the Sun will take part in an annular eclipse. However, don't count yourself out if you reside elsewhere. Most of central Mexico, the majority of the United States and Canada will still get a partial eclipse event. Want to know more? Then read on...

The 2012 Solar Eclipse event is called annular because the Moon doesn't totally cover the Sun's disk. Why does that happen? The reason is because the Moon is slightly further from the Earth, so it presents a smaller disk. This far point is called apogee. When it is closer in its orbit and appears to have a larger disk, it is known as perigee. However, just because the Moon is at apogee doesn't mean the eclipse isn't going to be an awesome sight... it means it will appear like a ring of fire!

The annular eclipse path is a narrow one. Why? Like creating a hand shadow on the wall, the shadow of the lunar orb can only be so big at a certain distance from the light source. This year the shadow path for the United States begins in north-central Texas, traverses through New Mexico, clips Arizona, Nevada and Utah and ends with the northern quarter of California and a very small edge of southern Oregon.

For partial eclipse viewers, the path begins in eastern Canada, making a diagonal swoop which passes through central New York and Pennsylvania. It continues south taking in Kentucky, Tennessee, Alabama and central Mexico. From there, the action heads west where the central United States and Canada witness around half of the event. For the western third of the US, you're in luck... While the partial event won't entirely cover the Sun, about 88%, you will get to see it from beginning to end!

Now, it's about time For those living in the east, the solar eclipse will be in progress as the Sun sets and gradually gain "time" as the solar show heads west. If you want precise times for your location, then use NASA's Solar Eclipse Explorer. It's a time calculator which is very specific to your locale.

Last, but certainly not least, is safe eclipse viewing. "The exposed part of the Sun will remain blindingly bright — literally so — so anyone viewing any part of this eclipse, partial or annular, must use a safe solar filter, such as a #13 or #14 rectangular arc-welder’s glass or an astronomer's filter made specifically for Sun viewing." says Alan MacRobert of Sky & Telescope magazine. "Ordinary dark glasses won’t do. Watching the Sun through an inadequate filter (or none) can permanently damage your eyesight." Plan in advance exactly how you will be viewing and make a practice run (or two!) if you're thinking about taking pictures.

However, the fun doesn't quite end! Look around and you'll notice Venus about a hand span away to the East... and the much dimmer appearance of Mercury and Jupiter to the west. Be sure to take note of the sky's appearance, too. The quality of "sky blue" becomes richer and deeper with less sunlight around!

Written by Tammy Plotner. 2004 Annular Eclipse Sequence courtesy of John Chumack. Eclipse Path Graphic courtesy of Sky & Telescope Magazine.

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