Skylights featured on Astronomy Picture of the Day

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

Full Moonset

Photo of the Week.. The full Moon and the Earth's shadow set to the west in early morning twilight.

Astronomy news for the week starting Friday, January 17, 2003.

The full Moon sails across the sky during the early part of the week, the exact phase reached on Saturday, the 18th, around the time of Moonset in the Americas, causing the Moon to set almost exactly at sunrise. The night of Friday the 17th, the near-full-Moon will rise just before sunset, the following night just after. Since the Earth has just passed the winter solstice in Sagittarius, the full Moon will reside just to the east of the Summer Solstice, which places it nicely among the stars of Gemini just to the south of Castor and Pollux. Toward the latter part of the week, on Thursday, the 23rd, the Moon passes perigee, where it is closest to the Earth. As our companion wanes through its gibbous phase, rising ever later, it passes north of Jupiter during the day of Sunday, the 19th. The Moon will therefore be just to the northwest of Jupiter the night of the 19th and to the northeast of the giant planet the night of Monday the 20th. Full Moon is the best time to admire the extent of the lunar "seas," the "maria," which are made not of water, but are shallow oceans of dark solidified lava that fill huge impact basins. These spots, all of which are named, make the "man in the Moon" and other fanciful figures. That we see them always in the same position shows that the Moon rotates such that it keeps one face pointed toward Earth at all times, the result of tides raised by the Earth on the Moon.

Four planets are now readily visible, Jupiter (well marked this week by the Moon), Saturn, which sits high in Taurus rather well to the west of Jupiter and just to the northwest of Zeta Tauri, brilliant Venus, which outshines everything in the pre-dawn morning sky except for the Moon itself, and much fainter Mars, which falls due west of Venus and to the northwest of Scorpius. The others are tucked in too close to the Sun, with the exception of Pluto, which is far too faint to be seen without substantial optical power. The little planet is in the morning sky, Mars, Venus, and Pluto all rather in ordered line and angularly equidistant from each other.

The autumn constellations, including the great figures of the Perseus myth, are slowly making their exit. As the sky darkens, Andromeda and Pegasus are to the west of the meridian, while the villain in the story, Cetus the Whale or Sea Monster (who is to devour Andromeda) lies due south. While not a brilliant constellation, the Whale's rather circular head stands out nicely to the southwest of Taurus. Far to the north of it are the graceful curves that make Perseus, the slayer of Cetus, while to the south lies the western bend of Eridanus, the River.
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