On paper, May of 2013 looks like a pretty exciting month in astronomy, because there will be not one, but two eclipse events this month. Unfortunately for those of us living in North America, the first of these, a spectacular annular solar eclipse, won’t be visible. And while the second eclipse, a penumbral lunar eclipse, will be able to be seen in North America, there will be virtually nothing to see.
The annular eclipse of the sun will take place on May 9th. An annular eclpise is when the long umbral shadow cone of the Moon is too short to reach the Earth. In angular size, the Moon’s disk will appear about 4 1/2 percent smaller than the disk of the Sun, so the effect will be like placing a penny atop a nickel; a ring of sunlight will remain visible surrounding the Moon. The shadow path where the ring can be seen runs for thousands of miles, but will get no wider than 107 miles at greatest eclipse. Much of the path falls over the Pacific Ocean, but at or soon after local sunrise, the eclipse will slice across northern Australia, the extreme eastern tip of Papua New Guinea, and some of the nearby Solomon Islands. At the point of greatest eclipse, the ring phase will last 6 minutes 4 seconds.
Partial Eclipse Begins: 5:25 p.m. – Annular Eclipse Begins: 6:30 p.m. – Greatest Eclipse: 8:25 p.m. – Annular Eclipse Ends: 10:20 p.m. – Partial Eclipse Ends: 11:25 p.m.
The penumbral eclipse of the moon will begin late in the evening on May 24th, ending about an hour later, on the 25th. This eclipse is virtually a nonevent; the Moon’s lower limb barely grazes the Earth’s faint penumbral shadow. Although much of North America will be turned toward the Moon during the eclipse, there will be absolutely no trace of any perceptible darkening.
Moon Enters Penumbra: 11:44 p.m. – Middle of Eclipse: 12:10 a.m. Moon Leaves Penumbra: 12:36 a.m.
While the moon and sun may disappoint North American sky watchers this month,the planets will more than make up for it. During the period from May 23 to 29, three bright planets–Venus, Jupiter and Mercury–will gather closely together low above the west-northwest horizon, about 45 minutes after sunset. Such an unusual configuration is called a “trio.” The three planets will fit within a 5° circle – small enough to fit inside the bowl of the Big Dipper – during this time. They will appear closest together on May 27, when they’re separated by less than 2 1/2 degrees. Astronomers have named this configuration, which will shift over the following weeks, “the Dance of the Planets.”