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The Sky This Week, 2009 November 10 - 17

Will the Leonids Roar Again?

The Moon may be found waning in the pre-dawn sky this week as her crescent becomes ever slimmer.  New Moon occurs on the 16th at 2:14 pm Eastern Standard Time.  Luna may be seen within 10 degrees of the golden glimmer of Saturn on the mornings of the 12th and 13th.  On the morning of the 14th she lies just three degrees due south of the bright blue star Spica.  You’ll probably need binoculars to spot the Moon’s hairline crescent some six degrees south of bright Venus in the bright twilight half an hour before dawn on the 15th.

The absence of the Moon enhances your prospects for observing one of the most fickle of sky phenomena, the annual Leonid meteor shower.  Every year the Earth blunders into the scattered bits of dusty debris sputtered from the surface of Periodic Comet Tempel-Tuttle, which orbits the Sun once every 33 years.  From 1999 through 2001 the shower produced spectacular displays; in 2000 I gave up counting after seeing some 400 shooting stars in an hour observing from the suburban skies of Alexandria.  The following year we saw almost as many from the same spot.  Generally these outbursts coincide with the passage of the comet through the inner solar system, so most astronomers seem content to wait until 2033 for the next bug burst.  However, a number of people have been intensely studying the distribution of debris bands from different perihelion passages of the comet, and a number of them think that we may get a brief, intense burst of activity this year.  They think that we might encounter a particularly rich plume from the 1466 pass of the comet, and thus it may just be worth your while to get up before dawn on the 17th or around midnight on the 18th.  Peak activity under the best conditions heavily favor observers in Asia, but the Leonids are often full of surprises.  The shower members tend to be very swift, fairly bright, and often leave a short train in the sky that fades after several seconds.  Under “normal” circumstances a single observer can expect to see around 10 Leonids per hour; outbursts can raise that figure to several hundred!

Much easier to spot is the bright planet Jupiter, who sits on the meridian as evening twilight deepens.  Old Jove beams down from the barren autumnal sky with no bright rival except the lonely first-magnitude star Fomalhaut, some 25 degrees southeast of the giant planet.  Your best telescopic views of Jupiter now take place around the dinner hour, so set the telescope up as soon as you get home and enjoy the best he has to offer.  By 9:00 pm he’s just 20 degrees above the southwest horizon.

Jupiter’s departure signals the arrival of ruddy Mars, who may now be seen cresting the eastern horizon at around 10:30 pm.  By 1:00 am he’s well up in the east, coursing his way between the Twin Stars of Gemini, Castor and Pollux, and Regulus, the blue-tinted heart of Leo, the Lion.  Mars not only outshines these bright stars, his orange-pink tint makes him very easy to identify.  Small telescopes should now just be able to start resolving detail on his distant disc.

Saturn is slowly making his way through the western stars of the sprawling constellation Virgo.  He’ll be spending the year in this neighborhood, reaching opposition in the spring.  Early risers can get a good view of him and his gradually opening rings through the telescope at the start of morning twilight.

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