Annular Solar Eclipse – May 20, 2012

If you haven’t heard, there’s going to be an annular solar eclipse on Sunday, May 20, 2012. For a REAL astronomer’s take on it, I recommend going to Dr. Plait’s blog HERE and HERE. And, of course, the most thorough rundown can be found at the NASA Eclipse Site.

Essentially, an annular eclipse is one in which the moon eclipses the sun sufficiently close to its apogee that it blocks all but a ring of the sun’s surface. Since we just had a “Super Moon” when the moon was at its perigee on the other side of Earth almost two weeks ago, the moon is now at its apogee as it blocks out the sun. Cool, huh?

I live in north Texas, so I’m out of luck seeing the whole eclipse with my own eyes since the sun will set just before the eclipse reaches totality. Even so, I’m not sufficiently in line with the moon’s shadow to see an annular effect in any case. However, with my Android phone and Google Sky Map, I won’t have any problem monitoring the eclipse in real time.

The eclipse begins at 15:56 CDT. Here’s how that will appear on my phone:

Eclipse begins

Eclipse begins

And at sunset (note the horizon line), just before totality, here’s how things will look:

Eclipse before sunset

For those who witness totality, I’d be interested to know if it was dark enough for Jupiter or Mercury to be visible. Also, if you’ve been tracking the planets, you should be able to answer this question: If Mercury is visible during totality, what will its phase be? You’ve got two choices.


As the moon approaches the sun, Sky Map shows it crossing in front of Jupiter. However, that’s just a consequence of Sky Map’s tendency to render planets much larger than they actually appear in the sky. Still, it’s fun to see the sun, Jupiter, Mercury, and the moon so close together.

People (like me) who are somewhat off to the side of the moon’s shadow will not witness totality. They will instead see a crescent sun as the moon obscures a large portion of the sun’s southern or northern hemisphere. If you’re in this situation, and you’re monitoring the solar eclipse in real time on Sky Map, set your location to Albuquerque, NM. People in that city will see totality. Does it look any different than it does in north Texas (depicted above)?

This is the amazing thing about having an app like Sky Map. If you’re stuck in an office cubicle, if the weather’s cloudy, or if you’re not in the right place on Earth to see the eclipse, you can still watch it as it happens on your phone. Yeah, I know, it’s just an app with a digitally-rendered sky. But try it anyway. If you watch the eclipse on your phone as it’s happening, trust me: you’ll feel a connection to the sky that can’t be described. There’s no feeling like it.


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