The moon glides directly in front of the sun this month. A total eclipse? Strangely, no. An odd annular eclipse will unfold, sweeping across the United States in the premier celestial event of the year.
That the moon and sun normally appear to be the same size is a happy accident. The sun is 400 times larger than the moon, but it happens to lie 400 times farther away. The result is a near perfect match, allowing the two to align occasionally for the stunning phenomenon of darkness at noon. But because the moon’s elliptical orbit carries it 28 to 32 Earth diameters from us, the moon now and then fails to block the sun totally even when the alignment is right. That’s what will happen on May 10. Because the moon will be near its far orbital point when it eclipses the sun, it won’t appear quite large enough ...
