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2009 January 2 - 12
The Moon waxes in the evening sky this week, climbing up to join the bright stars of the Great Winter Circle by the week’s end. First Quarter occurs on the 4th at 6:56 am Eastern Standard Time. Full Moon follows on the 10th at 10:27 pm. January’s Full Moon is popularly called the Wolf Moon or Moon after Yule. Look for Luna just east of the Pleiades star cluster on the evening of the 7th. The Full Moon shares the sky with Castor and Pollux, the Gemini Twins, on the night of the 10th. By now most of you have probably noticed that the time of sunset is inching ever later in the evening. On January 4th sunset in Washington will occur at 5:00 pm, 14 minutes later than it did back on December 7th, when we had our earliest sunset for the season. However, the time of latest sunrise is now upon us, and that date also corresponds to the 4th, when Old Sol peeks over the horizon at 7:27 am. Sunset will start to regress by the week’s end. The total length of daylight is now just four minutes longer than it was at the solstice, but this week we tack on another 10 minutes to that figure, a sure sign that winter is slowly beginning to wane. Also on the 4th, Earth reaches perihelion, its closest distance to the Sun, at around 10:30 am. We’ll be only 147 million kilometers (just over 91.4 million miles) from Old Sol at this time. Brilliant Venus continues to dominate the early evening sky, but if you have a flat western horizon go out about half an hour after sunset and look for the pinkish glimmer of Mercury, who reaches greatest elongation east of the Sun on the 4th. The fleet planet is passing through a very sparse region of the sky, so there is nothing else that will give him any competition except Jupiter, who lies just over two degrees below Mercury on the evening of the 2nd. Mercury quickly pulls away from the giant planet, though, and by the week’s end Old Jove will be almost completely lost in twilight glow. Mercury should remain visible until at least the 10th. Late night skywatchers can now get a glimpse of Saturn before midnight if they have an open eastern horizon. The ringed planet rises at around 10:30 pm on the 2nd, and by the 12th he comes up well before 10:00. If you train your new Christmas telescope on him and don’t see his famous rings don’t return your telescope as defective! The Earth is crossing the distant planet’s ring plane this year, and the rings will appear as little more than short spikes flanking the planet’s golden disc for most of the current apparition. I’ll be attending the annual Meeting of the American Astronomical Society next week, so the next update for “The Sky This Week” won’t appear until after I return. I’d like to thank all of the readers who have supported this feature for all of the past years. Thanks to your efforts we’ll be jumping to the new Navy Oceanography Portal on January 15th. You’ll still find us at the same domain, www.usno.navy.mil, and we’ll still have a link on the top-level page. For information on the Phoenix Mars mission, click here. For information on the MESSENGER mission to Mercury, click here. For information on the Cassini/Huygens mission to Saturn, click here. For information on Mars Exploration Rover activities this week, click here. For more information on meteor showers, click here. For more information on observable comets, click here. For more information eclipses and planetary transits, click here. For more information on the digital pictures on this page, click here. For information on BRIGHT SATELLITES passing over Washington, DC this week, click here. Last Modified: 2009 JAN 02 (grc)
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