Sunday, November 17, 2013

This Week's Sky at a Glance for November 16 - 23, 2013

Saturday, November 16

Tonight, look above the Moon for the leading star or two of Aries glimmering through the moonlight. To the Moon's left are the Pleiades. Much farther left twinkles bright Capella.

Mercury is now in the midst of its finest morning apparition of 2013. The planet lies 10 ° high in the east-southeast 45 minutes before sunrise, an altitude it maintains for the next three days. (Mercury officially reaches its greatest elongation west of the Sun tomorrow.) The inner world shines at magnitude 0.5, which is easily bright enough to see with naked eyes though binoculars will help you pick it out of the twilight glow. When viewed through a telescope, Mercury's 7 " appears half-lit.

Sunday, November 17
Full Moon arrives at 15:16 UT. The Moon lies among the background stars of Taurus the Bull, between the conspicuous Hyades and Pleiades star clusters. Unfortunately, the bright Moon puts a damper on the annual Leonid meteor shower, which peaks before dawn today. For the best views of these "shooting stars," wait until an hour or two before dawn, when the Moon lies low in the west and you can use a stand of trees or a building to block it.

Comet ISON is within 2 ° of Spica this morning and Monday morning. Their closest approach, 1/3 °, comes around 1h November 18th Universal Time, good timing for observers in the longitudes of eastern Europe and western Asia.

Monday, November 18
This evening look right of the just-past-full Moon for Aldebaran. Later in the evening, Orion rises below them.

Comet ISON (C/2012 S1) experienced a notable outburst this past week, which brought it into naked-eye visibility to those viewing under dark skies. If you are seeking your first views of this interplanetary interloper, the bright star Spica now serves as a convenient guide. The comet's head lies less than 2 ° below Virgo's 1st-magnitude luminary this morning; it lay a similar distance above the star yesterday. The pair rises nearly three hours before the Sun and appears some 10 ° high in the east-southeast by the time twilight starts to paint the sky. Binoculars or a telescope at low power will provide the best views of the comet

Tuesday, November 19
After 9 or 10 this evening, you'll find the waning gibbous Moon shining inside a huge quadrilateral: Capella to the Moon's upper left, Aldebaran to the Moon's upper right, Betelgeuse closer to its lower right, and bright Jupiter far to its lower left .

Mars rises just after 1 am local time this week and appears nearly halfway to the zenith in the southeastern sky by the time twilight begins. Although several stars appear brighter than magnitude 1.5 Mars, the planet stands out for its ruddy color. A telescope reveals a bland disk measuring just 5 "across.

Wednesday, November 20
By late evening the waning Moon is up in the east. It's now part of a long, ragged, roughly horizontal snake. From right to left: Rigel in Orion's foot in the east-southeast, Orion's Belt, Betelgeuse, the Moon, Jupiter, Pollux, and above Pollux, Castor.

A lone bright star now hangs low in the south during early evening. First-magnitude Fomalhaut - often called "the Solitary One" - belongs to the constellation Pisces Austrinus the Southern Fish. From mid-northern latitudes, it climbs 20 ° above the horizon at its best. How solitary is Fomalhaut? The nearest 1st-magnitude star to it, Achernar at the southern end of Eridanus the River, lies some 40 ° away.

Thursday, November 21
The waning gibbous Moon passes 5 ° south of brilliant Jupiter tonight. The two rise around 8 pm local time and appear nearly overhead by 3 am Both will appear in the same binocular field of view against the background stars of Gemini the Twins. Point a telescope at Jupiter and you'll see a 44 "-diameter disk with at least two parallel dark belts in its massive atmosphere.

Friday, November 22
The Moon reaches apogee, the farthest point in its orbit around Earth, at 9:49 UT. It then lies 251,931 miles (405,443 kilometers) from Earth's center and appears almost imperceptibly smaller in our sky. To see it, however, you'll have to wait until it rises shortly after 9 pm local time.

Saturday, November 23
The variable star Algol in Perseus reaches minimum brightness at 01:06 UT, when it shines at magnitude 3.4. If you start watching it after darkness falls this evening, you can see it more than triple in brightness, to magnitude 2.1, over the course of a few hours. This eclipsing binary star runs through a cycle from minimum to maximum and back every 2.87 days. Algol appears in the northeastern sky after sunset and passes nearly overhead around 11 pm local time.

Sources: Sky & Telescope & Astronomy Magazine

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