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31 Oct 2018

November Astronomy: Take Advantage of the Time Change to Enjoy Incredible Views of Venus This Month

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In November 2018, Venus is the up-and-coming morning “star.”

Next inward from Earth in our solar system, fast-moving Venus overtook our planet in late October while passing nearly between Earth and sun. Day by day in November, Venus rockets higher into the southeastern morning sky. Rising in twilight a full hour before sunup by Nov. 4, Venus’ rising time improves to two hours before sunup on Nov. 13, and three hours before on Nov. 27. (Graphic credit: Jeffrey L. Hunt.)

As it becomes visible in a dark predawn sky before the onset of twilight, Venus also increases in brilliance to magnitude -4.9—as bright as it ever gets. That’s easily bright enough to spot it in the daytime. One easy way to do that is to find Venus before sunup, and keep track of it until after sunrise.

This is the best time to enjoy Venus through a telescope, or even binoculars. On Nov. 1, Venus shows as a very thin crescent, less than 2 percent illuminated, and a full arcminute (one 60th of a degree) across. A magnification of just 30 power then makes Venus appear a half-degree across, about as large as the moon with the unaided eye. The illuminated portion of the crescent Venus thickens to 5 percent by Nov. 7; 10 percent by Nov. 13; 15 percent by the 19th; and 25 percent by the 30th. By month’s end, the apparent size of Venus has shrunk to 0.7 arcminute—still large enough to resolve the crescent shape with 7-power binoculars.

Observe Venus early enough for the sky to be dark—an hour before sunrise is enough—and you’ll notice it has a stellar companion close by. It’s blue-white first-magnitude Spica, within 5 degrees of Venus Nov. 4-28; within 2 degrees Nov. 10-19; and as close as 1 1/4 degrees on Nov. 14. This type of pairing—where a planet approaches a star or another planet within 5 degrees, but doesn’t pass it—is called a quasi-conjunction. You might think of this month’s rare Venus-Spica event to be a “kissing conjunction,” where the participants get so close … but then one of them has a change of mind.

Enjoy these various aspects of Venus this month, despite the early hour, especially after we change our clocks back to standard time on Nov. 4. You won’t regret it!

Our morning twilight map for November shows Venus ascending over the east-southeast horizon to join Spica. Next in brilliance after Venus is Sirius, the Dog Star, in the southwest. It is the southern vertex of the huge Winter Hexagon, also including (in clockwise order) Procyon, Pollux and Castor; Capella at the northern vertex; Aldebaran; and Rigel, with Betelgeuse inside. Regulus, heart of Leo, follows the Hexagon across the sky, and golden orange Arcturus follows Regulus. The waning crescent moon appears near Regulus on the mornings of Nov. 1 and 2. On Sunday, Nov. 4, get out early to watch for Venus rising 26 degrees below the moon. On the 5th, the moon is 13 degrees to the upper left of Venus, and on the 6th, the last thin old crescent moon, some 25 1/2 hours before the new moon, is 9 degrees to the lower left of Venus.

The moon returns to the scene on Thanksgiving morning, Nov. 22, with the nearly full moon about to set in the west-northwest, 19 degrees to the lower right of Aldebaran, and 13 degrees to the lower left of the Pleiades star cluster. On this date, Spaceship Earth is heading directly toward Regulus, 90 degrees from the sun, and is passing between the Pleiades and the sun—so that cluster is at opposition, setting in the west-northwest as the sun rises in the east-southeast. Go out that morning, and visualize the motion of Earth around the sun, with Venus pulling farther ahead of us. The stars drift farther west each day, as shown by their tracks on the twilight maps—a direct result of the Earth’s revolution around the sun. Venus will “round the bend” in our view of its orbit in early January 2019, and next will head toward the far side of the sun, where it will pass, invisibly, in August.

On the mornings of Nov. 23 and 24, the moon will leapfrog past Aldebaran. The waning gibbous moon will appear to the lower left of the “Twin” stars Pollux and Castor on the morning of Nov. 26, and to their upper left the next morning. The moon will appear closely to the upper left of Regulus on Nov. 29.

On our evening twilight chart for November, the Summer Triangle passes west of overhead; Mars remains in the south-southeast with Fomalhaut lower down; and Saturn gets lower in the southwest. Arcturus sinks into the west-northwest twilight glow, while replacement Capella ascends in the northeast. Late in the month, below the Pleiades, watch for Aldebaran rising in the east-northeast to the lower right of Capella. Binoculars, very clear skies and an unobstructed view toward the west-southwest to southwest will be needed to spot Jupiter and Mercury, and only early in month. If all these conditions are met, you might try for Mercury 5-6 degrees to the left of Jupiter on Nov. 1 and 2. Jupiter drops out, but Mercury lingers for another week. Try for Mercury 9 degrees to the left of the 2 percent crescent young moon on Nov. 8, and 7-8 degrees below the 6 percent moon on Nov. 9.

It will be much easier to spot Saturn within 8 degrees to the upper left of the moon on Nov. 10, and within 5 degrees to the lower right of the moon on Nov. 11. Mars will appear only about 2 degrees to the upper left of the 54 percent moon, just past first quarter phase, on Nov. 15. One week after it passes Mars, on Thanksgiving evening, Nov. 22, the full moon will rise just 3 minutes after sunset, although with all the mountains surrounding us, it would be impossible to verify. That evening, as the sky darkens, look for the Pleiades cluster 9 degrees to the moon’s upper left, and Aldebaran, the “follower” of the Pleiades, 11 degrees to the moon’s lower left. On the next night, Nov. 23, the moon rises about 50 minutes after sunset. Look for Aldebaran 3-4 degrees to the upper right of the rising moon. Binoculars will help. On Sunday, Nov. 25, the month’s northernmost moonrise occurs 2 hours and 40 minutes after sunset, well after the end of twilight, so the sky will be very dark for a short time before it brightens again due to moonlight. Within an hour after the moon appears, look for Orion to the right of the moon, and the “Twin” stars Pollux and Castor, 12-14 degrees to the moon’s left.

The website of the Astronomical Society of the Desert at www.astrorx.org has a listing of our evening star parties at two locations. Sawmill Trailhead, our high-altitude site (elevation 4,000 feet), will have a star party starting at dusk on Saturday, Nov. 10. Our primary, more-accessible star-party site is the Visitor Center of the Santa Rosa and San Jacinto Mountains National Monument, on Highway 74, within 4 miles south of Highway 111 in Palm Desert. Our next monthly star party there is scheduled for Saturday, Nov. 17, from 5 to 8 p.m. Also, beginning in late October, check the Impromptu Star Parties link. I’ll be offering sky watches in Palm Springs at the pedestrian bridge over Tahquitz Creek at North Riverside Drive and Camino Real—at dusk to catch Saturn while it’s still visible, and at dawn to welcome Venus as the morning star.

Abrams Planetarium publishes a monthly Sky Calendar with an evening sky map. Subscriptions are $12 per year at www.abramsplanetarium.org/skycalendar for three printed issues mailed quarterly.

Wishing you clear skies!

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing sky watching opportunities for a variety of groups in the Coachella Valley. Robert D. Miller did graduate work in planetarium science and later astronomy and computer science at Michigan State University and remains active in research and public outreach in astronomy.

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