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31 Jan 2017

February Astronomy: Venus Reaches Peak Brilliance, While Californians Miss Out on a Partial Lunar Eclipse

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Venus reaches peak brilliance, near magnitude -4.9, in February’s evening sky—giving rise to lots of UFO reports!

Through a telescope or even 7-power binoculars, the planet displays an ever-larger and thinner crescent, especially if viewed in daytime or at sunset. Venus appears 39 percent full and a half-arcminute across on Feb. 1, and only 17 percent full and 0.8 arcminute across by Feb. 28. (One arcminute equals 1/60th of a degree.) Try locating Venus in daylight when it’s highest and due south: On Sunday, Feb. 5, Venus is 59 degrees up at 2:44 p.m.; Feb. 12, 62 degrees up at 2:32 p.m.; Feb. 19, 65 degrees up at 2:16 p.m.; Feb. 26, and 67 degrees up at 1:55 p.m.

Find Venus easily with the unaided eye by sunset or shortly thereafter, 45 degrees to the sun’s upper left, on Feb. 1, to 33 degrees directly above the setting sun on Feb. 28. At dusk, Venus is in the west-southwest to west, getting lower as month progresses. Much fainter Mars (about magnitude +1.2) is 5 to 12 degrees to its upper left. Next in brilliance after Venus is the blue-white twinkling “Dog Star” Sirius (the brightest star, at magnitude -1.5) in the southeast to south, and next is yellowish Capella, the Mother Goat star, just northeast to north of overhead. Sirius and Capella mark extreme south and north vertices of the huge “Winter Hexagon,” with Betelgeuse and Orion’s belt inside. At the start of February, Regulus, heart of Leo the Lion, rises north of east over an hour after sunset. By Feb. 17, it rises at sunset and can be seen all night long.

In morning twilight: Jupiter, well up in the southwest as dawn brightens, ranks first in brightness in this month’s morning sky. Before the sky brightens too much, note Spica,about 4 degrees away. Catch bright Mercury very low in the east-southeast in the first week. The most prominent stars at dawn are golden Arcturus, high above the Jupiter-Spica duo, and blue-white Vega, high in east-northeast. Look also for Altair and Deneb, completing the Summer Triangle with Vega. Find steady yellow Saturn in the southeast with twinkling reddish Antares to its right.

Changes in predawn sky: In mid-February each year, the Earth’s orbiting motion carries us in a direction between the stars Spica and Antares, toward a spot in the sky 90 degrees west of the sun. As we face between those stars before dawn in mid-February, we are looking out the “front window” of Spaceship Earth. Go out an hour before sunrise and visualize how the motions of the Earth and other planets, orbiting at different speeds, will change the positions of planets and stars in our predawn sky. Speedy Mercury is now pulling away from Earth, and in early February sinks into the solar glare and disappears on the far side of the sun. On the night of February 17-18, our planet will pass between the sun and Regulus, and that star will appear at opposition, visible all night, low in the east at dusk, high in the south in the middle of night, and low in the west at dawn. Regulus appears lower in the west each morning.

As for the moon: On Tuesday, Jan. 31, the four-day-old waxing crescent forms a beautiful compact gathering with Venus and Mars. For the next few evenings, Venus and Mars remain 5.4 degrees apart. Meanwhile the moon moves on, passing widely south of the Pleiades (Seven Sisters) star cluster on Feb. 4; skipping past Aldebaran, eye of Taurus, by Feb. 5; getting by the Gemini twins, Pollux and Castor, by Feb. 8; and reaching full and rising at sunset on Friday, Feb. 10. That evening, sunset and moonrise occur simultaneously at 5:26 p.m. (assuming no mountains block the view), but that’s almost 45 minutes too late to catch the moon in deepest penumbral eclipse. Tell your friends east of the Rocky Mountains to look for a slight dusky shading covering the left or upper left part of the moon at 5:44 p.m. MST, 6:44 p.m. CST, or 7:44 p.m. EST. A much more impressive total lunar eclipse will be visible on Jan. 31, 2018—when Californians will have a great view!

A bit later in the evening of Feb. 10, watch for the rising of Regulus below the moon. The moon closes in on that star for the rest of the night, until dawn. On subsequent evenings, watch the waning moon rise later each night, farther south each time: on Feb. 11 at 6:28 p.m.; on Feb. 12 at 7:28 p.m.; on Feb. 13 at 8:26 p.m.; on Feb. 14 at 9:23 p.m. Or you can shift your viewing times to mornings, about an hour before sunrise. On the morning of Feb. 15, look for the beautiful gathering of the waning gibbous moon, Jupiter and Spica in the southwest an hour before sunrise. By Feb. 19, a fat crescent moon will appear above Antares, heart of the Scorpion. On Feb. 20, the one-third-illuminated lunar crescent will appear above Saturn, in the south-southeast. In morning twilight on Feb. 24, the 5 percent crescent is still easy to see, but very low in the east-southeast. Spotting the thin old 1 percent crescent, 25 hours before new, some 25-30 minutes before sunrise on Feb. 25, will be very difficult, requiring binoculars and very clear skies.

After new moon on Feb. 26 at 6:58 a.m., our first chance to see the waxing crescent will be at dusk on Monday, Feb. 27, when the 1.5-day old 3 percent moon will be very low, just south of due west, and far below and a little left of Venus. At dusk on Feb. 28, the 8 percent crescent moon appears about 10 degrees to the lower left of Venus.

The Whitewater Preserve will be hosting a star party on Saturday, Jan. 28, weather permitting, beginning at 6:30 p.m. Reservations are requested at 760-325-7222.

The Astronomical Society of the Desert will host the next of our series of monthly star parties on Saturday, Feb. 4 and March 4, from 6 to 9 p.m. They are held at 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. Also, check www.astrorx.org for listings of our high altitude star parties at Sawmill Trailhead starting at dusk. The next high-altitude star party (at 4,000 feet—wear warm clothes!) will be Saturday, Feb. 18. Follow links to maps and directions to both star party sites, and for dates and locations of lecture meetings. The meeting at 7 p.m., Friday, Feb. 10, at the Portola Community Center in Palm Desert will feature astronomy author Dennis Mammana on “The Great American Total Eclipse: August 21, 2017.”

Also, check the link to our “Impromptu Star Parties,” which could be announced on short notice at any time.

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs. 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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