If you happen to be around the Four Corners area on October 14, make sure to have your solar-eclipse glasses with you, and you’ll be able to tell your friends that you saw an eclipse from four different states!
An annular solar eclipse will grace our skies that morning, with the full eclipse beginning around 9:30 MST and lasting for just under five minutes. People will be enjoying this path of totality along a swath of the US stretching from the Oregon coast to South Texas.
An annular eclipse is a type of solar eclipse, where the moon is directly between the Earth and Sun. With a total solar eclipse the moon completely covers the sun’s disk, but with an annular eclipse it covers the center, leaving a slim ring of sunlight visible around it. This halo is the annulus, from the Latin anulus (‘finger ring’), which in mathematics is defined as the area between two concentric circles.
We have both total and annular eclipses because of the non-circular nature of the moon’s orbit. While we may think of them as neat circles, the orbital paths that objects in space usually follow are ellipses. At one point in its elliptical orbit, called the perigee, the moon is closest to us and we experience “supermoons,” as we saw in August (twice!). At the opposite point, the apogee, it’s as far away as it gets. So when the moon is at apogee during a solar eclipse, its apparent diameter is not enough to fully cover the sun, giving us a “ring-of-fire” eclipse that’s quite the sight to behold.
Whether total or annular, solar eclipses happen about twice each year, though with more than 70% of the planet’s surface covered by water they’re not always conveniently visible. In addition, the earth’s rotation can put a viewable eclipse path on any continent, making the few we can see locally unique events.
The path of this month’s annular eclipse will be only around 120 miles wide as it tracks across the western US, down Central America and across Colombia and Brazil, but viewers hundreds of miles away from the path of totality will still experience a partial eclipse. Here in central Yavapai County we’ll see approximately 82% coverage of the sun’s face that morning.
Enjoy, and again, be safe, don’t forget your solar glasses!
If you would like to learn more about the sky, telescopes, or socialize with other amateur astronomers, visit us at prescottastronomyclub.org or Facebook @PrescottAstronomyClub to find the next star party, Star Talk, or event.
Adam England is the owner of Manzanita Financial and moonlights as an amateur astronomer, writer, and interplanetary conquest consultant. Follow his rants and exploits on Twitter @AZSalesman or at Facebook.com/insuredbyadam.
