In the early morning hours of January 26, the Moon will slip in front of the Sun producing a solar eclipse visible to observers on the Indian Ocean. This eclipse is a bit unusual, however, in that the Moon will be near the apogee of its orbit around Earth. As discovered by Johannes Kepler in the 17th century, orbits are not circular as the prevailing wisdom of thousands of years assumed, but are instead elliptical. The Full Moon of two weeks ago occurred when the Moon was at the closest point in its orbit around earth—perigee—and the New Moon of January 26 will occur near the farthest point from Earth (apogee.) Since the Moon will be slightly farther from Earth than usual, it will cover a smaller area of the sky. Add to this the fact that Earth is near the closest point in its orbit around the Sun (perihelion) at this time of year and the circumstances result in the Moon appearing just a bit too small to cover the visible disk of the Sun. The result is a ring of the Sun’s disk remaining visible producing a annular eclipse.
Note: Because the Sun’s visible disk is not completely obscured (the maximum coverage will be about 93%), it is NOT safe to look directly at the eclipse without protective filters. If protective filters are not available, the Sun’s image can be projected so that the projected image can be observed.
Fred Espenak’s “Mr. Eclipse” graphic for the January 26 annular eclipse.
Visit spaceweather.com for animations, videos and photo galleries of the eclipse.