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May 10: Can you catch Comet Tempel 2?
Asteroid 13 Egeria is a great 10th-magnitude target in the evening sky, already high after sunset as it floats through the large constellation Virgo. Today is a particularly good day to view it, as it’s passing near magnitude 5.7 80 Virginis, offering a clear signpost against which to measure the asteroid’s drift in just a couple of hours.
A few hours after sunset, Virgo is high in the south. It’s easy to find its brightest star, magnitude 1.0 Spica, about 40° above the horizon and due south around 11 P.M. local daylight time. Egeria lies above and slightly to the left of this star, 6° north-northeast of it. There, you should spot a faint star by eye — that’s 80 Vir. Tonight, Egeria is just less than a degree from this star, located to its southwest. The asteroid is also moving southwest, away from the star and toward a fainter, 9th-magnitude field star. Center your view on 80 Vir and draw a quick sketch or snap a photo, then come back in two or three hours. In a comparison sketch or shot, you should notice Egeria’s movement.
Sunrise: 5:49 A.M.
Sunset: 8:05 P.M.
Moonrise: 2:50 A.M.
Moonset: 2:21 P.M.
Moon Phase: Waning crescent (28%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. local time from the same location.
Early risers on May 12 have a great view of a lunar feature normally located near the limb. An hour before sunrise, the Moon is roughly 20° above the eastern horizon. About 25 percent of its nearside is still lit, as sunset slowly occurs across the lunar disk.
Zoom in on the lunar southwest with a telescope and you’ll immediately notice a broad, shallow crater with a bright eastern rim and a dark, flat floor. This is 132-mile-wide (212 kilometers) Schickard, a circular feature that often appears artificially elongated thanks to its location near the limb. Today, though, it should look more round than on other occasions, as lunar libration — the nodding or wobbling motion of our Moon as it orbits — brings it more into view, carrying it farther from the limb.
Look particularly at Schickard’s floor: Some but not all of it has been flooded with lava. There should be a noticeable textural difference between the southwest and northeast regions within the walls. Additionally, several smaller craterlets pockmark the floor, showing that they came much later than the initial impact that formed the larger Schickard.
