It’s not just the annual income tax deadline that expires tomorrow. The Moon will also be going out—though like taxes, it will reappear, and 364 days sooner.
In the wee hours of tomorrow morning, stargazers in the Western Hemisphere will start losing sight of the moon. For 78 minutes, the southern half of Earth’s umbral shadow will block the sun from illuminating the features of our only satellite. At totality, the Moon will attain its “ring of fire” appearance. The northern half of the Moon will appear much darker than the southern half because it lies deeper in the umbra.
Fred Espenak of The Observer’s Handbook explains why:
At the instant of greatest eclipse (07:45:40 UT) the Moon lies at the zenith for a point in the South Pacific about 3000 km southwest of the Galapagos Islands. The umbral eclipse magnitude peaks at 1.2907 as the Moon’s northern limb passes 1.7 arc-minutes south of the shadow’s central axis. In contrast, the Moon’s southern limb lies 9.0 arc-minutes from the southern edge of the umbra and 40.0 arc-minutes from the shadow centre.
The fiery moon will contrast greatly with the nearby bright blue star Spica, in the constellation Virgo, during the eclipse. Also tonight, the planet Mars will be making its closest approach to Earth in the past six years (within 57.4 million miles [92.4 million km]) of our planet.) Red as always, Mars will shine as strongly as Sirius, the brightest star in the sky.
The table at right gives more detail about the eclipse from American time zones. Thanks to Alan MacRobert of Sky and Telescope for this detailed schedule! MacRobert also guides readers through the highlights of the five eclipse phases in his article.
Four consecutive total lunar eclipses will take place this year from Earth, a coincidence that only happens once every decade or so. The next will be visible over all of North America except the farthest northeast on the morning of October 8.