Skylights featured on Astronomy Picture of the Day

Scout Report Selection Webivore Selection SpaceCareers Selection

Skylights featured nine times on Earth Science Picture of the Day: 1 2 3 4 5 6 7 8 9 -- Full List Restored!


Photo of the Week.. Will it clear?

Astronomy news for the two weeks starting Friday, December 21, 2012.

Best wishes to all for a fine holiday season, a good year in 2013, and clear skies. The next Skylights will appear January 4, 2013.

The Moon starts off our fortnight just past its first quarter, so leads with its waxing gibbous phase, which ends at full Moon the morning of Friday, December 28, about the time of Moonset in North America. Our second week is then spent admiring the waning gibbous phase, which endures until third quarter arrives the night of Friday, January 4. The big event is another close passage between the bright Moon and Jupiter on Christmas night, the Moon (coincidentally at its apogee) climbing the sky with Jupiter on top (the Moon actually occulting the bright planet as seen from parts of South America and Africa). The previous evening, look for Jupiter to make a neat triangle with the Moon and the Pleiades: providing you can make them out in bright moonlight.

With us nearly all night, Jupiter dominates the sky, appearing high to the south in the hours before midnight, and by the end of our period still not setting until after 4:30 AM well in the northwest. In the morning, while Saturn enters more and more into the scene (at the New Year rising in dim western Libra around 2:30 AM), Venus (though as always still very bright) crosses a bit of a line, as at year's end it rises just as twilight begins to light the sky. In the last of planetary news, Pluto (once the "last planet") ends the year in near-conjunction with the Sun.

The fortnight begins with the Sun at the Winter Solstice in Sagittarius, which announces the start of astronomical winter, giving us the shortest day and longest night. Then around midnight on New Year's Day (as the first goes to the second), the Earth passes perihelion, where it is closest to the Sun, 1.7 percent closer than the average of 149.6 million kilometers (92.96 million miles), obviously showing that solar distance has nothing to do with the seasons (which are caused by the 23.4 degree tilt of the rotational axis against the orbital perpendicular). Finally, one of the better meteor showers of the year, the Quadrantids (named after a defunct constellation near the handle of the Big Dipper), peaks the night of Wednesday the 2nd (morning of the 3rd), but will be marred by a bright Moon.

In mid-evening, look for the roundish head of Cetus, the Whale or Sea Monster, about half way up the sky, his body floating off to the west. If you can't find it (once the Moon is out of the way), the vee-shaped head of Taurus, the Bull (just to the south of Jupiter), points right at it.
Valid HTML 4.0!