SKYWATCHER'S DIARY: January 1996

Abrams Planetarium

SKYWATCHER'S DIARY:
January 1996

To the reader

The Skywatcher's Diary for January 1996 has been prepared by Robert C. Victor. Sometimes you can see next month's in advance by looking in our archives. Credit to Abrams Planetarium, Department of Physics and Astronomy at Michigan State University would be appreciated. Our illustrated Sky Calendar accompanies the printed version of Skywatcher's Diary as it is sent monthly to Michigan newspapers, but does not accompany this Internet version. If you would like a sample copy, send your request with a self- addressed, stamped envelope to

Sky Calendar
Abrams Planetarium
Michigan State University
East Lansing, MI 48824

A sample Sky Calendar of a past month is available over the Internet. It can be accessed via a World-Wide Web browser such at Netscape or Mosiac, directly at URL:

http://www.pa.msu.edu/abrams/novskycal.html

Lunar and Planetary Highlights for January

At dusk at the start of January, three planets are visible with unaided eye: Brilliant Venus in the southwest, Saturn over 30 degrees to Venus' upper left, and Mercury near the horizon to Venus' lower right. Mercury sinks and fades in January's second week, while Venus and Saturn approach each other all month, the gap between them closing by just over one degree each day. Dawn watchers can see Jupiter emerge from the Sun's glare on the ESE to SE horizon in January's 2nd week. Look for a thin crescent Moon near Jupiter on Jan. 18, and an even thinner crescent to Jupiter's lower left on the next morning. The first easy view of an evening crescent occurs at dusk on Jan. 21, with the Moon climbing near brilliant Venus on Jan. 22 and near Saturn on Jan. 23. Venus and Saturn approach within 5 degrees apart by Jan. 28, and 2 degrees apart by Jan. 31. (They will appear closest to each other on Feb. 1 and 2.) The Moon can be found very near the star Aldebaran at dusk on Jan. 2 and again one true lunar orbital period (27.3 days) later on the night of Jan. 29.

Astrophotography Project:
The Conjunction of Venus and Saturn

Using a 35-mm camera with a standard lens (about 50-mm focal length), take nightly photographs of Venus and Saturn against background stars. Use a tripod to steady the camera, and fast film such as Ektachrome 400. On clear evenings Jan. 20-Feb. 14, one-and-a-half hours after sunset, take a 15-second exposure with a wide-open fast lens such as a 50-mm f/1.2 to 2.8. The field of view of a 35-mm camera with a standard lens of 50-mm focal length is about 36 degrees by 24 degrees. For each photo, aim the camera to orient the long dimension of the field vertically, with the horizon just within the lower edge of your field. You'll obtain an impressive set of teaching slides showing the fast eastward motion of Venus and slow eastward motion of Saturn against background stars, the relative motion of Venus past Saturn, and the seasonal drift of the starfield toward the western horizon.

Monday, January 1

At nightfall, brilliant Venus is low in SW, while the Pleiades (Seven Sisters) star cluster is high in the eastern sky 7 degrees to the Moon's upper left. Follow Venus and the Pleiades for the first four months of 1996; in early April they'll pass very close to each other in the western evening sky.

Tuesday, January 2

Mercury appears farthest from the Sun tonight. Forty-five minutes after sunset, look for brilliant Venus in the SW, with Mercury 14 degrees to its lower right. Using binoculars, can you see Mars within 6 degrees to Mercury's lower right?

The first-magnitude star Aldebaran, eye of Taurus the Bull, appears within a couple of degrees of the Moon at dusk. Look every hour as the evening progresses, and watch them separate, owing to the orbital motion of the Moon around the Earth.

Wednesday, January 3

Remember how close to each other Aldebaran and the Moon appeared last night? This evening at dusk, the Moon has moved on, and appears some 13 degrees to the east (lower left) of that star.

Thursday, January 4

Orion is magnificent, even when low in the sky in twilight and bright moonlight. An hour after sundown, look for reddish Betelgeuse, Orion's bright shoulder, 12 degrees right of the Moon tonight. The Hunter's belt, a vertical line of three stars, appears 10 degrees right of Betelgeuse. Rigel, Orion's foot, lies 9 degrees right of the belt. The opening lines of Robert Frost's poem, "The Star-Splitter", has a good description of Orion rising:

"You know Orion always comes up sideways. Throwing a leg up over our fence of mountains,..."

Friday, January 5

Does the Moon seem unusually large when it rises in ENE shortly after sunset this evening? Actually, it's only an illusion, since this Moon after Yule happens to be the most distant Full Moon of 1996.

Saturday, January 6

The Moon rises tonight about 1-1/4 hours after sunset, the exact time depending on your location. Another hour later, look in the east for Procyon 11 degrees to the Moon's right. Another 26 degrees right of Procyon [and a bit lower, from northern U.S.], look for twinkling Sirius, the Dog Star and brightest star of the nighttime sky. You can also locate Sirius by following Orion's belt down toward the ESE horizon.

Sunday, January 7

At nightfall, locate Saturn in SW, 29 degrees upper left of Venus. Before the Moon rises, while Saturn is still well up in a dark sky, view Saturn through a good telescope. You'll see a dark band across the face of the planet, which consists mostly of the dark face of Saturn's rings, and partly the rings' shadow. But can you also see the darkened rings to the sides of the planet? You have a good chance to detect them this week. Although their shaded side is now tipped toward Earth, the rings aren't *completely* dark, because they're not solid. Some sunlight reflected from the rings' lighted side manages to make it through the rings toward Earth.

Monday, January 8

Some 4-1/2 hours after sunset, face east to see Regulus, heart of Leo, about 7 degrees lower left of the Moon. They keep company for the rest of the night; at dawn on Tuesday, they're in the WSW, with Regulus above the Moon.

Tuesday, January 9

Some 4-1/2 hours after sunset, the Moon has just risen in the east, with Regulus 8 degrees above it.

Wednesday, January 10

Some 45 minutes after sunset, binoculars help locate Mercury 20 degrees lower right of Venus in SW. Mercury will sink and fade quickly in the remainder of this week, but Saturn, 25 degrees upper left of Venus tonight, remains in easy view. A week from today, Mercury passes inferior conjunction, nearly between Earth and Sun. Around such times Mercury is invisible, because it appears as a faint, thin backlighted crescent only a few degrees from the Sun. Late this month, Mercury will reappear in the ESE at dawn.

Thursday, January 11

Castor and Pollux, two bright stars just 4-1/2 degrees apart marking the heads of the Gemini twins, are now visible all night: Low in ENE at dusk, high in S in middle of night, and low in WNW at dawn. That's because in the second week of January each year, as we face these stars, we are looking outward, directly away from the Sun. Keep track of these "Twin" stars an hour after sunset evenings until late June, and watch how they appear to drift across the sky as the Earth revolves around the Sun.

Friday, January 12

An hour before sunup on Saturday, the Moon is in SSW. Just over 90 degrees (1/4 circle) west of the Sun, the Moon is approaching Last Quarter phase and is still slightly more than half full. Look for Spica about 5 degrees to Moon's lower left.

Saturday, January 13

The Moon is in the south an hour before sunrise on Sunday. It has passed Last Quarter phase and is visibly less than half full. Note Spica 8 degrees to the Moon's right.

Sunday, January 14

In mid-January each year, the Summer Triangle is visible both at dusk and again at dawn. Altair, its lowest and southernmost star, is low in west at dusk and low in east at dawn. Vega and Deneb are 34 and 38 degrees away from Altair and farther north. At dusk, Deneb marks the top of the triangle. At dawn, Vega, the triangle's brightest star, marks the top.

Monday, January 15

An hour before sunup on Tuesday, the waning crescent Moon is in SSE with the three stars of the head of Scorpius just below. Reddish twinkling Antares, heart of the Scorpion, is 12 degrees to Moon's lower left. Can you see bright Jupiter just risen in ESE to SE, 24 degrees to Antares' lower left?

Tuesday, January 16

An hour before sunup on Wednesday, the thin crescent Moon is in SE. First-magnitude Antares, the Scorpion's heart,lies 9 degrees to the Moon's lower right, while bright Jupiter has just risen 19 degrees to Moon's lower left.

Wednesday, January 17

An hour before sunrise on Thursday, a very pretty crescent Moon is low in SE with Jupiter about 5 degrees below. Jupiter rises about two hours earlier with each passing month; around midyear Jupiter will rise at sunset and be up all night, near the Full Moon on the night of June 30.

Thursday, January 18

Last chance to see the old Moon: About 45 minutes before sunup on Friday morning, look low in SE for Jupiter, with a very slender Moon 12 degrees to its lower left. From mid-Michigan, it'll then be only about 24-1/2 hours before Saturday's New Moon. A Friday morning sighting from the West Coast would be only about 22 hours before New. A sighting from Hawaii would be about 20 hours before New. Binoculars enhance the view of the very delicate crescent. Note the times you last see the Moon with unaided eye and with optical aid.

Friday, January 19

The closest New Moon of the year occurs Saturday morning, at 7:50 a.m. Eastern Standard Time (4:50 a.m. Pacific Time, 2:20 a.m. Hawaii Time). Seacoasts may have unusually high tides. If you saw the old Moon this morning, calculate the time interval from your last sighting until the time of New Moon. When you see the young Moon in the early evening on Saturday or Sunday, calculate the interval from New Moon until the time of sighting.

Saturday, January 20

Will anyone near the U.S. West Coast or in Hawaii see the extremely young Moon tonight? The first *naked eye* sighting of the young Moon determines the start of the Islamic holy fasting month of Ramadan, but the first such sighting will be possible only from Hawaii or even farther west. An optically aided sighting from the U.S. West Coast would set a new record for the youngest Moon ever seen, a scant 13 hours after New, or even less. It'll be very difficult, with the short faint lunar arc in bright twilight within 8 degrees above the Sun. Using binoculars or a telescope, look 20 to 25 minutes after sunset, very low in WSW, 31 degrees lower right of Venus and 6 degrees right of Mars. [But Mars might not be visible.] Even from Hawaii, the Moon will still be only 9- 1/2 degrees from the Sun and less than 16 hours after New, but might just be possible with unaided eye!

A westerner who catches both the old Moon on Friday and the young Moon this evening might set an additional record for the minimum time between "opposing crescents". From Mauna Kea, Hawaii, the ages of the Moon at civil twilight (when the sun is 6 degrees below the horizon, about 24 minutes before sunrise and after sunset) are -20.2 hours on Friday morning and +15.7 hours on Saturday evening, an interval of 35.9 hours.

Sunday, January 21

The slender crescent young Moon is an easy and beautiful sight at dusk. Look in the WSW, about 18 degrees lower right of Venus. From mid- Michigan, the Moon's age is about 34 hours, from the U.S. West Coast, 37 hours. Watch for the earthshine on the Moon's dark side each evening this week. Will you still see it at week's end?

Monday, January 22

The two brightest nighttime objects, Venus and the Moon, make a spectacular pair for three hours after sunset. Try to see Venus in the daytime by using the Moon as a guide. Right at sunset, they're about 6 degrees apart, with Venus to the Moon's upper left. A much closer pairing of these bodies awaits us on Feb. 21.

Tuesday, January 23

Tonight the Moon forms a pretty pair with Saturn; they're 4 degrees apart, with Saturn to the Moon's left. Venus gleams 10 degrees below them.

Tonight, both Earth and Sun are nearly one degree from Saturn's ring plane, but on opposite sides. If your telescopic image of Saturn were large and sharp enough tonight, the dark band across the face of Saturn would be resolvable into two equal components: The rings' *shadow*, and their *unlit face*. In coming weeks, the shadow widens and the ring face narrows, until on Feb.11 the rings are presented exactly edgewise to Earth and completely disappear. Beginning Feb. 12, we'll see the *illuminated face* of the rings off to the sides of the planet, first as a very narrow line of light, growing broader nightly.

Wednesday, January 24

By tonight the Moon climbs well above the two evening planets. Find Saturn about 13 degrees below the Moon at dusk and some 9 or 10 degrees upper left of brilliant Venus.

Thursday, January 25

The Moon, still a crescent tonight and Friday, passes First Quarter phase early on Saturday and will appear just over half full that evening. These evenings, with the Moon close to half full, are ideal for using binoculars and small telescopes to study lunar surface features.

Friday, January 26

As darkness falls, note the Great Square of Pegasus in the west, to the upper right of Venus. Tonight Venus aligns with two stars to its upper right, the west side of the Great Square. Look nightly and watch for the alignment to change. On Feb. 12, Venus will line up with the two stars on the east (trailing) side of the Square.

Saturday, January 27

By Sunday at dawn, Mercury attains first magnitude very low in ESE at dawn. Forty-five minutes before sunup, look 14 degrees lower left of Jupiter. Binoculars help. Mercury gets higher daily all next week and doubles in apparent brightness by week's end.

Sunday, January 28

Countdown to the great Groundhog Day conjunction of Venus and Saturn, the best evening pairing of planets this year: With 5 days to go, the planets are 5 degrees apart! Face SW at dusk. Venus is the lower and brighter.

Monday, January 29

At nightfall the Moon is nicely framed by the V-shaped head of Taurus, which consists of first-magnitude Aldebaran and the Hyades. Use binoculars to see the faint Hyades in the Moon's glare. Look hourly to follow the Moon's motion against the stars. From Michigan, the Moon's southern edge slides one degree N of Aldebaran around 1 a.m. EST tonight.

Tuesday, January 30

Countdown to the Groundhog Day conjunction: With 3 days to go, Venus-Saturn are 3 degrees apart!

Wednesday, January 31

Good things come in pairs! Tonight at dusk, Saturn is 2 degrees upper left of brilliant Venus in WSW. For rest of week at dawn, locate Mercury low in ESE, 13 degrees lower left of bright Jupiter. Look daily.

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