Solar eclipse this week

If you live in Australia, the Solomon Islands, or Papua New Guinea, then this is your lucky week.  On Friday, residents of this corner of our planet (and anyone stuck in the ocean in between!) will have a front-row seat to what should be a spectacular partial solar eclipse.  At its peak, 95% of the Sun will be covered, causing it to appear as a "ring of fire."

Progression of a 2012 partial solar eclipse.

Solar eclipses occur when the Moon passes directly between the Sun andEarth, partially or totally blocking our view of the Sun.  If the Moon had a perfectly circular orbit that lay directly in the plane of the Earth's orbit, we'd see an eclipse every month.  Instead, the Moon's orbit is inclined a few degrees and a little bit elongated.  This means that usually the three bodies don't line up correctly and no eclipse occurs.

Not every planet-moon system can experience a total  or near-total eclipse.  The size of our moon, the size of its orbit, and our distance from the Sun have all lined up rather fortuitously for these kinds of eclipses to even be possible.  This has been put to good use by astronomers - total solar eclipses allowed us to study the outer layers of the Sun (called the corona) long before we otherwise could have.

Remember, even if 95% percent of the Sun's light is blocked, it is still really bright.  Never look directly at the Sun or a solar eclipse without the protection of solar eclipse glasses.