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 , 4 .

Dancing clouds

Photo of the Week.. Clouds dance on a stage of blue...

Astronomy news for the week starting Friday, January 21, 2005.

The Moon begins our week in its waxing gibbous phase as it heads to full the night of Monday, January 24, the phase actually taking place the next morning, that of Tuesday the 25th about the time of Moonset. The near-full-Moon will thus rise just before sunset the night of the 24th.

This full phase is particularly far north. The Moon's orbit is tilted by about 5 degrees to the plane of the orbit of the Earth about the Sun. As a result, the Moon can be as much as 5 degrees north of the ecliptic (the apparent path of the Sun against the background of the stars) and 5 degrees south of it. At this full Moon, which will be just to the east of Castor and Pollux in Gemini, the Moon is nearly at the full extent of its tilt to the north and well above the ecliptic plane. The effect is made obvious by the planet Saturn, which currently lies practically smack on the ecliptic, and will appear 5 degrees to the south of the Moon the morning of Monday the 24th. Two days before full, the Moon passes apogee, where it is farthest from the Earth. The remainder of the week sees our companion in its waning gibbous phase.

Venus and Mercury, still close together, are effectively gone from the morning sky. Bright as it is, rising only in mid dawn, Venus is now near impossible to see because of the brightening sky. The morning sky is thus left with Mars, now well east of Antares, Jupiter (just to the west of the meridian at dawn), and Saturn, which is near to setting at that hour. The early evening is host to Saturn alone, the planet tucked nicely into Gemini, already risen as evening comes to a close, and transiting the meridian about 11:30 PM. Just as Saturn transits, Jupiter rises, the giant planet just to the northwest of Spica in Virgo, the ecliptic just passing between the two. Be sure to keep following the news about Saturn's satellite Titan.

Comet Machholz, visible to the naked eye, but really best in binoculars, is now trekking northerly through the bright stars of Perseus. The night of Saturday the 22nd, it will pass just to the west of Mirfak, Alpha Persei.

Though the stars of winter are now full upon us, do not forget the so-called stars of autumn, which are still on full -- and best -- view in early evening. As the sky darkens in mid-northern latitudes, Cassiopeia is nearly overhead and to just to the west of the meridian, while Perseus is just to the east of it. The line between the two passes to the south first through extreme eastern Andromeda, then down through Triangulum, Aries (both simple triangles), and then on to the more-or-less circular head of Cetus, the Sea Monster, who in myth was slain by Perseus in the rescue of Andromeda.
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