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The astronomical story that is drawing the most attention in November is Comet ISON, discovered on Sept. 21, 2012.
At that time the comet was still beyond the orbit of Jupiter and ISON’s brightness was unusually high for a comet that far from the sun. This gave rise to speculation that ISON could be brilliant by the time it makes its closest approach to the sun on Nov. 28.
That said, ISON has not brightened as fast as expected. As of Oct. 18, ISON was still far too dim to see with the naked eye.
While ISON could surprise us, current predictions (late October) indicate that you’ll need binoculars to see ISON in much of November.
Looking east about 4 a.m. Friday, Comet ISON appears about 12 degrees (slightly more than the width of your fist at arm’s length) southwest of Denebola, the second-magnitude star in the tail of Leo. If you can find Mars, ISON is about 7 degrees below the red planet.
Comet ISON is moving fast, and will move 1 degree per night (twice the diameter of a full moon) against the starry background in early November. Since the comet is moving from west to east, like the planets do in their regular motion, this means ISON will rise a little later each morning in November.
Spica, by far the brightest star in Virgo, is a useful reference for locating ISON in mid-November. White-blue Spica rises at 4:35 a.m. on Nov. 15, just south of due east. Once you spot Spica, Comet ISON will be 8 degrees to the west-northwest. The comet will appear closer each night, passing within 2 degrees of Spica on the 17th.
The comet should brighten substantially during these days. It may well be a naked-eye object by this time. ISON will be closer to the horizon by daybreak each day, so we’re playing a game between the brightening of the comet and the glow of the rising sun.
There is a big helper in finding ISON in these predawn skies around Nov. 22: he planet Mercury. Look for Mercury as it rises in the east at 5:25 a.m. Then look right about 5 degrees (a little more than two fingers at arm’s length), and you’ll find the comet. (Mercury will be 4 degrees above Saturn.)
After Nov. 23, the comet will be hard to see, as the comet heads for its passage past the sun. The comet makes its closest approach to the sun, or perihelion, on Thanksgiving Day.
This passage through perihelion is the moment of truth. No one knows if the comet will break apart as it goes through or if it will emerge intact. If it does survive the passage, it may well be a striking object in the December morning skies.
Find out more at www.astronomy.com/ison.
PLANETS
Venus is that airplanelike dot about one-third of the way up in the west as it gets dark. Venus is very consistent in November: It emerges partway up in the west at dusk and sets at 8:45 p.m. Look for the waxing crescent moon close to Venus on the nights of Nov. 5 and 6.
At minus 2 magnitude, Jupiter is by far the brightest morning dot in November. At the start of the month, Jupiter rises in the east at 10:45 p.m. and is in the top of the sky at daybreak. By the end, Jupiter rises at 8:45 p.m., goes exactly through the zenith at 3 a.m., and is about halfway down the western sky as day breaks. Look for the waning gibbous moon next to Jupiter on the nights of Nov. 21-22 and 22-23.
Mars remains pretty dim in the morning sky in November. The planet, whose naked-eye brightness varies far more than any other planet, shines at a mere 1.5 magnitude in early November. It rises in the east at 2:30 a.m. in early November and is halfway up in the east at daybreak. At the end of November, Mars rises by 1:30 a.m. and is two-thirds of the way up in the east at dawn. Look for the waning crescent moon next to Mars on Nov. 26 and 27.
Mercury’s best morning appearance in 2013 occurs in November. Look for the planet in the east from Nov. 7 to the end of the month. It rises at 5:45 a.m. on Nov. 7 and is briefly visible before day breaks just after 6 a.m. By Nov. 17, the time of its greatest apparent distance from the sun’s disk, Mercury rises in the east at 5:15 a.m., has grown in brightness and is 12 degrees above the horizon (a fist’s diameter) by daybreak an hour later.
Mercury remains visible before dawn all the rest of the month. The planet swells in brightness from magnitude 1.6 on Nov. 7 to minus 0.65 on Nov. 30.
Saturn emerges in the morning sky in late November. As early as Nov. 20, look for Saturn rising in the east at 5:50 a.m. It shines at 0.5 magnitude and is just below the brighter light of Mercury. Saturn will appear closer and closer to Mercury each morning till Nov. 25, when the ringed planet will be just half a degree (the width of a full moon) below Mercury. From then to the end of November the two planets switch places, with Saturn now above brighter Mercury.
The gathering is lovely but short-lived; you only have from about 5:50 to 6:15 a.m. to catch this pair anytime from Nov. 20 to 30.
SPACE STATION
If skies are clear, the International Space Station will make a spectacular pass on Thursday. The station will rise in the northwest at about 6:30 p.m. and set in the southeast at about 6:37.
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Mike Shanahan is director of Education, Exhibits and Planetarium. For more information, go to www.bishopmuseum.org/planetarium/planetarium.html
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