November 2011: Mercury lurks just 2° below Venus during November's first 2 weeks. You'll need a clear sky and an unobstructed southwestern horizon to see the more challenging innermost planet.
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| The two inner planets (Venus at left and Mercury to its right) passed within a few degrees of each other April 4, 2010. The pair repeats this performance in November’s evening sky. Rick Stankiewicz |
Half an hour after sunset this November, Venus stands out in the southwestern sky. The planet shines at magnitude –3.9 — far brighter than any other point of light in the sky. It becomes even more obvious with each passing minute as the bright blue sky turns a deeper and darker azure.
Mercury lurks just 2° below Venus during November’s first 2 weeks. You’ll need a clear sky and an unobstructed southwestern horizon to see the more challenging innermost planet. Glowing at magnitude –0.3 throughout this period, Mercury appears just 4 percent as bright as its neighbor. The pair sets about an hour after the Sun.
These two planets maintain their relative positions because both move eastward against the background stars at about the same rate. You can track their nightly progression using the 1st-magnitude star Antares as a guide. The star seems to approach the pair from the left before sliding beneath both November 9. That evening, Mercury passes 2° north of Antares and Venus lies 2° farther north. You’ll likely need binoculars to pull Antares out of the twilight glow.
Mercury reaches its greatest eastern elongation November 14. The planet then reverses direction and heads back toward the Sun while Venus continues to move away. Mercury dims and sinks deeper into the twilight, disappearing from view before the month ends.
Venus, on the other hand, grows more prominent in November’s second half as it climbs higher. A nice photo opportunity occurs November 26 when a waxing crescent Moon passes 3° from Venus. That same evening, the planet sits less than a degree southwest of the Lagoon Nebula (M8) in Sagittarius. Astroimagers will have no trouble capturing the Moon and planet together; recording the fainter nebula against the deep twilight presents a formidable challenge. Venus ends the month 1° northwest of 3rd-magnitude Lambda (λ) Sagittarii, the star that marks the tip of the constellation’s Teapot asterism, and sets nearly 2 hours after the Sun.
These two planets maintain their relative positions because both move eastward against the background stars at about the same rate. You can track their nightly progression using the 1st-magnitude star Antares as a guide. The star seems to approach the pair from the left before sliding beneath both November 9. That evening, Mercury passes 2° north of Antares and Venus lies 2° farther north. You’ll likely need binoculars to pull Antares out of the twilight glow.
Mercury reaches its greatest eastern elongation November 14. The planet then reverses direction and heads back toward the Sun while Venus continues to move away. Mercury dims and sinks deeper into the twilight, disappearing from view before the month ends.
Venus, on the other hand, grows more prominent in November’s second half as it climbs higher. A nice photo opportunity occurs November 26 when a waxing crescent Moon passes 3° from Venus. That same evening, the planet sits less than a degree southwest of the Lagoon Nebula (M8) in Sagittarius. Astroimagers will have no trouble capturing the Moon and planet together; recording the fainter nebula against the deep twilight presents a formidable challenge. Venus ends the month 1° northwest of 3rd-magnitude Lambda (λ) Sagittarii, the star that marks the tip of the constellation’s Teapot asterism, and sets nearly 2 hours after the Sun.
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| Mercury and Venus lie no more than 2° apart during this month’s first half. First-magnitude Antares joins the pair November 9 and 10. Astronomy: Roen Kelly |
It’s worth spending a few minutes each night viewing Mercury and Venus through a telescope. The innermost planet orbits the Sun faster, which translates into a more rapid transformation. On November 1, Mercury appears 5.4" across and 84 percent lit. By the 15th, the disk spans 6.7" and is 62 percent illuminated. Venus exhibits more subtle changes. During the course of November, its apparent diameter grows from 10.6" to 11.5" while its phase dwindles from 94 percent to 89 percent lit.
If you look about halfway up in the southern sky after darkness falls, you’ll find the sprawling constellation Aquarius. And tucked into a corner of the Water-bearer, near its border with eastern Capricornus, lies the distant planet Neptune. This ice-giant world remains 1.7° northwest of 4th-magnitude Iota (ι) Aquarii throughout November.
Neptune glows at magnitude 7.9, which makes it bright enough to see through firmly held 50mm binoculars. (For a steadier view, try mounting them on a tripod.) If you turn a telescope on this distant world, you’ll see a blue-gray disk that measures 2.3" across.
Some 30° east and a bit north of Neptune lies its solar system sibling, Uranus. The easiest way to find Uranus is to start with autumn’s most distinctive asterism: the Great Square of Pegasus. This group lies due south and more than two-thirds of the way to the zenith at 8 p.m. local time in mid-November. From the Square’s center, drop about 20° south to a circular group of a half-dozen stars in Pisces known as the Circlet asterism. Uranus lies about one binocular field southeast of the Circlet’s center.
Glowing at magnitude 5.8, Uranus is easy to pick up through binoculars. You can even glimpse it with naked eyes under a dark sky, although it helps if you first locate it with binocs. Don’t confuse this world with a slightly fainter (magnitude 6.3) star that stays within 0.5° of it all month. You can confirm Uranus’ identity by targeting it through a telescope at medium magnification. The planet shows a 3.6"-diameter disk with a noticeable blue-green color.
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| Ganymede's black shadow stands out against Jupiter's clouds November 14/15, just after the moon clears the planet's western limb. Astronomy: Roen Kelly |
Spotting Uranus and Neptune requires a little bit of time and effort. Jupiter makes no such demands. Head outside on any clear November night and you can’t miss the brilliant planet. It shines at magnitude –2.9 (only the Moon and Venus glow brighter) and lies in a sparsely populated region near the border between Aries and Pisces.
Jupiter reached opposition and peak visibility in late October, but it declines so slowly that the views this month are nearly as good. The most significant change in the planet’s appearance is a positive one — it rises earlier and thus appears higher in the evening sky.
The image of Jupiter through a telescope never ceases to impress. The gas-giant world’s apparent equatorial diameter shrinks slightly in November, from 50" to 48", although that’s still plenty big enough to reveal many details. The most obvious features are two relatively dark equatorial belts, which reside above and below a brighter equatorial zone that bisects the planet’s disk. A series of alternating dark belts and bright zones shows up on nights when Earth’s atmosphere steadies and telescopic views sharpen.
Features within Jupiter’s cloud belts, including festoons, barges, ovals, and the Great Red Spot, show up with longer looks. Spending time at the eyepiece trains your eye to see finer details on display in the jovian atmosphere. Careful observers can see features change position within 10 to 15 minutes as Jupiter’s rapid spin carries them across the planet’s disk.
The presence of up to four bright moons significantly enhances Jupiter’s appearance. Io, Europa, Ganymede, and Callisto shine bright enough to see through any telescope as long as they aren’t passing in front of or behind the planet. (They would appear to naked eyes if the brilliant planet didn’t overwhelm them.)
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| Conspicuous Saturn returns to view in November's morning sky, where it forms half of a colorful pair with Virgo's brightest star, Spica. Astronomy Roen Kelly |
The most exciting observation is to watch a moon and its inky-black shadow cross Jupiter’s bright cloud tops. You can witness a good example with Ganymede
the evening of November 14. At 7:13 p.m. EST, this moon first touches Jupiter’s southeastern limb. It then tracks across the planet’s southern hemisphere for more than
90 minutes, exiting the disk at 8:46 p.m. EST. Just 4 minutes later, Ganymede’s shadow starts a similar trek. The dark spot marches across the jovian clouds from 8:50 p.m. to 10:45 p.m. EST.
You’ll have to wait until morning for another prominent planet to appear. Mars pokes above the eastern horizon around midnight local time and grows more conspicuous as it climbs higher in the predawn sky. It lies among the background stars of southern Leo, passing 1.4° north of the Lion’s brightest star, Regulus, the morning of the 10th. The planet then shines at magnitude 1.0, which is 0.3 magnitude brighter than the star. Note the color contrast between ruddy Mars and blue-white Regulus.
Mars grows larger during November, swelling from 5.9" to 7.0" in apparent diameter. Observers with 8-inch or larger telescopes should see the white north polar cap along with more-subtle surface features during moments of good seeing.
Saturn returns to view following its mid-October solar conjunction, climbing quickly into a dark sky before dawn. By November 30, it stands 20° high in the southeast as twilight commences. Like Mars, Saturn has stellar company — in the ringed planet’s case, it’s Virgo’s luminary, Spica. The two remain within 5° of each other all month. Golden-colored Saturn shines at magnitude 0.8, slightly brighter than the blue-white star.
A telescope transforms Saturn from a point of light into a showpiece. The planet itself measures 16" across the equator while the ring system spans 36". By late November, the rings tip 14° to our line of sight, their largest tilt in more than 4 years. The wide angle affords earthbound observers magnificent views.
A partial solar eclipse occurs deep in the Southern Hemisphere November 25. Observers will see the Moon cover a tiny sliver of the Sun from South Africa (in the morning) and Tasmania (late afternoon). Those on New Zealand’s South Island will witness nearly 30 percent of the Sun disappear as our star sets. All of Antarctica sits under the Moon’s shadow; visitors to the South Pole can view the Sun diminished by nearly 80 percent. To avoid damaging your eyesight, be sure to view the eclipse through a safe solar filter.
Will the Lion sleep or roar?
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| The Leonid meteor shower peaks the night of November 17/18, although its shooting stars will have to battle a nearby Last Quarter Moon after midnight. Astronomy: Roen Kelly |
The Leonid meteor shower always brightens November’s sky. In some years, it does so only a little; in others, it brings a veritable storm of “shooting stars.” The occasionally wild swings from year to year depend on how Earth encounters the various debris streams laid down by the shower’s parent comet, 55P/Tempel-Tuttle.
Although astronomers caution that there’s no certainty with the Leonids, they don’t expect a spectacular show in 2011. The shower should peak before dawn November 18, when a Last Quarter Moon lies near the shower’s radiant in Leo the Lion. Observers with an otherwise dark sky can expect to observe up to 10 meteors per hour. To see the most, head out to the country and face away from the Moon’s glare.
Don't be afraid of the darkness
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| Shortly after First Quarter phase, the large craters Archimedes and Plato catch their first rays of sunlight. This northern hemisphere region abounds with smaller craters and mountain peaks. Consolidated Lunar Atlas/UA/LPL |
The first week of November features a waxing Moon that dominates the evening sky. Grab your telescope any clear night and scan along the terminator — the line dividing light and dark on the surface. In this region, the rugged lunar landscape casts long shadows.
First Quarter phase arrives November 2, when half our celestial neighbor appears lit. The next evening, observers start to glimpse the Moon’s western hemisphere. Look along the terminator halfway between the equator and the north pole, and you’ll see the perfectly circular crater Archimedes. The ragged rim of this 52-mile-wide impact structure projects spiky shadows onto its smooth lava-filled floor, and even longer spikes into the darkness to the west.
Two smaller craters lie east of Archimedes. Aristillus spans 34 miles and appears more impressive thanks to a distinctive group of three central peaks. The high rim and smaller size (24 miles across) of Autolycus keeps its floor in nearly complete shadow November 3.
North of these three craters, the solitary peak of Mons Piton sprouts above the wrinkled lava plains of Mare Imbrium. The large elliptical crater Plato lies northwest of Mons Piton. This crater’s rim appears as a broken outline in the early evening of the 3rd but fills in to become a complete ring in the next few hours.
Garradd offers a month of déjà vu
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| Comet C/2009 P1 (Garradd) crawls to the north and west this month against the stellar backdrop of southern Hercules. Astronomy: Roen Kelly |
Comet lovers can hardly believe their good fortune. Eight months ago, the brightest comets glowed at 13th magnitude and barely showed up through moderate-aperture telescopes under dark skies. But in November, observers have two comets to choose from, and both should be visible through binoculars or small scopes.
Leading the parade is 7th-magnitude Comet C/2009 P1 (Garradd). This first-time visitor to the inner solar system offers a distinct advantage to new observers — unlike most comets, Garradd hardly moves relative to the background stars. This means you can find it in essentially the same spot night after night. It resides against the backdrop of southern Hercules, a few degrees northeast of Alpha (α) Herculis. This region lies about one-third of the way from the western horizon to the zenith at the end of evening twilight.
The geometry of this encounter means that Garradd’s tail fans out to the northeast (almost straight up in the evening sky). Although the tail fades gradually, the comet’s head appears well-defined on its southwestern side. This is where material released from the icy nucleus interacts with the solar wind. Boost your telescope’s power past 100x, and you’ll see a bright spot near the head’s center. This is the inner coma; the nucleus remains hidden inside this cocoon of dust.
Our second comet is C/2010 X1 (Elenin). Astronomers expect it to glow around 8th magnitude in early November and dim to 12th magnitude by month’s end. Search for it before morning twilight during November’s first week, when it lies in southern Auriga and appears high in the west with the Moon out of the sky. It won’t be as easy to spot as Garradd because it is crossing the Milky Way.
California, here comes Eunomia
The constellation Perseus climbs high in the eastern sky on November evenings. Sliding in front of the gas and dust clouds at the Hero’s feet is asteroid 15 Eunomia. This minor planet swings close enough to Earth this month that it shines brighter than all others except 4 Vesta.
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| Eunomia reaches its peak in late November, when it glows at 8th magnitude while passing in front of the California Nebula (NGC 1499) in southern Perseus. Astronomy: Roen Kelly |
Eunomia begins November glowing at magnitude 8.3 and brightens to magnitude 7.9 by the month’s final week. It reaches opposition and peak visibility on the 28th, when it passes nearly overhead around midnight local time.
But that’s not the main reason to view Eunomia around opposition. During the month’s final days, it passes in front of the California Nebula (NGC 1499), which lies just north and east of 4th-magnitude Xi (ξ) Persei. Although this emission nebula appears prominent in photographs, it’s tough to see visually through a telescope. You’ll need a dark sky, and a nebula filter (Hydrogen-beta is best) definitely helps.
In contrast, Eunomia stands out from the field. Only a few stars in its immediate vicinity shine as bright as the asteroid. You can confirm which object is Eunomia by sketching the field and then returning a night or two later to see which dot of light moved.
Martin Ratcliffe provides professional planetarium development for Sky-Skan, Inc. Alister Ling is a meterologist for Environment Canada.
Quoted from Astronomy
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