SKY REPORTER: A Bright Setting for Winter's Gems
by Steve Beyer on
The day after Thanksgiving, as updated SOHO images showed ghostly shreds of comet ISON whipped beyond the Sun, hopes were crushed that we might enjoy a transfigured “Comet of the Century” this year. Although eventual scientific returns on ISON’s passage are expected to be significant, visual prospects that day were glum.
Things brightened for us at dusk while crossing Lexington Avenue at E. 31st Street, en route to dinner. As wary New Yorkers, we check for traffic both ways on one way streets. That caution yielded vistas that let us forget the erstwhile comet. Northward glistened the wonderful Art-Deco Chrysler tower draped with arching garlands of light. Then toward the south, we spotted Venus’ brilliance poised above vehicles dashing down Lexington. The planet shone like a sparkling diamond, holding its own nicely against the city’s dazzle.
Venus’ appearance reminds us the night sky provides refreshing orderly change as well as elements of constancy. December’s evening array of bright stars around the constellation Orion is bookended this year by complementary brilliance of Venus and Jupiter. Throughout December at about five pm, Venus is in the southwest then sets by the time the figure of Orion and bright Jupiter both ascend from the eastern horizon. In future years, these planets will move on to other settings along the zodiac and their current neat framing of this month’s evening stars will be gone.
Orion’s classic figure is highlighted by red supergiant star Betelgeuse at its northeast corner and the even more intense light of blue-white Rigel to the southwest. Each marks opposite parts of the celestial hunter’s traditional frame. Light we see from Betelgeuse takes somewhere between 500 and 650 years to reach us and the star’s vast diameter extends across a span approaching the size of Jupiter’s orbit. Betelgeuse is classified as a red supergiant, and the adjective “red” indicates the most intense individual colors in the blend of its visible glow. To my eyes, this remarkably named star appears yellowish-beige.
As beautiful counterpoint to Betelgeuse, Rigel is a blue-white supergiant with an estimated distance from us of about 850 light years and a diameter equivalent to the size of Mercury’s orbit. Rigel is the brightest member of a four star mutually orbiting stellar system.
The three stars marking the Belt of Orion appear halfway between Rigel and Betelgeuse and the set provides an eye-catching base for exploring other fine features of the winter evening sky.
We’ll be in the dome of the Hayden Planetarium Space Theater at 6:30 the evening of Thursday December 19 for the indoor segment of our Winter Solstice Telescope Party. If the sky is clear, we’ll later go out on Ross Terrace for sky viewing with telescopes courtesy of the Amateur Astronomers Association of New York. Participants are welcome to bring their own binoculars and telescopes. Here is more information about the event.
Winter begins in the northern hemisphere at 12:11 pm ET the afternoon of Saturday December 21th. At that time the Sun is directly above a point on the Tropic of Capricorn 500 miles west from the coast of Chile.
December’s Full Moon is Tuesday December 17th with traditional names including Full Cold Moon and Long Night Moon. This year it’s located among stars of Taurus.
|New Moon||December 2|
|First Quarter||December 9|
|Full Moon||December 17|
|Last Quarter||December 25|
The Full Moon appears north of Orion and west of Jupiter on the night of December 17-18. On Wednesday December 18, the waning gibbous moon is just five degrees of arc from Jupiter. The moon may be seen to the south of Mars during post-midnight hours of December 25 and 26. Between about five and six am the mornings of December 28 and 29, a narrow lunar crescent is low in the southeastern sky near Saturn.
|Mercury||Rises 6:40 a.m.||Ophiuchus|
|Venus||Sets 7:03 p.m.||Sagittarius|
|Mars||Rises 12:32 a.m.||Virgo|
|Jupiter||Rises 6:09 p.m.||Gemini|
|Saturn||Rises 4:18 a.m.||Libra|
|Uranus||Sets 1:05 a.m.||Pisces|
|Neptune||Sets 10:01 p.m.||Aquarius|