Skylights featured on Astronomy Picture of the Day

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Skylights featured four times on Earth Science Picture of the Day: 1 , 2 , 3 , 4 .

Moon and Flowers

Photo of the Week.. A Moon for Spring.

Astronomy news for short week starting Friday, April 11, 2003.

This is the week of the full Moon, the phase taking place on Wednesday, the 16th, during the day and well before Moonrise in North America. The closest view to the full Moon will therefore rise just after sunset the night of the 16th, the approaching-full rising just before sunset the night of Tuesday, the 15th. Less than a day after full, the Moon passes perigee, when it is closest to the Earth, the combination raising especially high tides at the coasts.

All the full Moons have traditional names, this one called the Grass Moon, the Egg Moon, the Planter's Moon. Full Moon is the best time to view the lunar maria (or "seas"), the dark spots that make the "man in the Moon." Never real "seas," the maria are dark lava flows that fill in ancient impact basins. All have names, the prominent one near the top to the east of center "Mare Imbrium," the "Sea of Showers," never mind that the Moon has essentially no water, all the names now just whimsical. Through the telescope, the famed craters all but disappear, as the Sun is directly overhead on the Moon's center, and there are no shadows to outline them.

The evening sky is highlighted this week by Mercury, which reaches its greatest eastern elongation, 20 degrees to the east of the Sun, on Wednesday the 16th. Though bright, the little planet will still be difficult to find, as it will be very low in the west in evening twilight. Better to admire Saturn, seen to the west in eastern Taurus as evening begins, and then very bright Jupiter, which is high to the south in fading evening twilight.

The morning sky is the domain of the two planets that flank the Earth: Venus and Mars, which are quickly separating. Venus, still very bright and noticeable, is now rising in the east rather well after twilight begins, while Mars is now rising in eastern Sagittarius around 2:30 AM Daylight Time.

That icon of the northern skies, the Big Dipper, now rides nearly overhead in late evening, as seen from the middle northern latitudes. Bisect the handle to the south, and you pass through a pair of stars that represent the modern constellation Canes Venatici, the "Hunting Dogs." Farther to the south you run into a filigree of stars called Coma Berenices (Berenices Hair), a real cluster whose stars are bound together by gravity. So in fact are the middle five stars of the Big Dipper, which together form the core of a cluster that is slowly breaking apart.
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