To the reader:
The Skywatcher's Diary for January 2006 has been prepared by
Robert C. Victor, formerly Staff Astronomer (now retired). Credit to the author and to
Abrams Planetarium,
Department of Physics and Astronomy at
Michigan State University, and mention of
our
Sky Calendar, would be
appreciated.
A sample issue of the Sky Calendar is available over the Internet. It
can be viewed via the World-Wide Web at
http://www.pa.msu.edu/abrams/SkyCalendar/Index.html
If you would like a printed sample of the January issue, please send a long,
self-addressed stamped envelope to:
January Sky Calendar
Abrams Planetarium
Michigan State University
East Lansing, MI 48824
Each month, the Department of Physics and Astronomy at Michigan State
University makes the Skywatcher's Diary available over the Internet. It can
be accessed at
http://www.pa.msu.edu/abrams/SkyWatchersDiary/Diary.html
Current and back-issues of the Skywatcher's Diary are available in our
archives
at
http://www.pa.msu.edu/abrams/SkyWatchersDiary/Archives.html
ftp://www.pa.msu.edu/pub/swd/
Naked-eye planets and Moon in January
At dusk, Mars climbs higher toward south as month progresses but fades
some. Saturn rises earlier in evening, and becomes an all-night object
outshining Mars late in month. With the departure of Venus, the "Dog
Star" Sirius becomes the brightest evening stellar object. Locate this
blue-white twinkling star in the early evening by extending Orion's belt
downward. Venus switches from low WSW at dusk to low ESE at dawn,
joining the two other morning planets, Jupiter in SSE to S and Saturn
descending in W to WNW.
The Moon is New on December 30, reaches First Quarter phase on Jan. 6,
Full on the night of Jan. 13-14, Last Quarter on Jan. 22, and New on
Jan. 29. The Moon appears near naked-eye planets on the following dates:
Venus at dusk on January 1, Mars on the evenings of Jan. 7 and 8, Saturn
on nights of Jan. 14 and 15, Jupiter on morning of Jan. 23, and Venus at
dawn on Jan. 27.
Following is a day-by-day guide to celestial happenings during January
2006. For drawings of many of these events, and an evening sky map,
request a free sample copy of the Abrams Planetarium Sky Calendar by
sending a self-addressed, stamped envelope to Sample Sky Calendar,
Abrams Planetarium, Michigan State University, East Lansing, MI 48823.
Or you can subscribe for $11 per year. We appreciate your subscriptions!
Skywatcher's Diary: January 2006
At sunset, the Moon is low in SW, and Venus is about 10 degrees to Moon's lower right and 19 degrees to Sun's upper left. Binoculars show Venus as a tiny crescent nearly 1/60 of a degree across and 5 percent illuminated, same phase as the Moon's! This is your last chance to see the Moon and Venus in conjunction at dusk until December 21 this year, shortly after Venus begins its next evening appearance. By this Sat. Jan. 7, Venus will be only 10 or 11 degrees above the setting Sun.
The Moon is higher than last night, Venus a bit lower. Venus is about 22 degrees to Moon's lower right. As sky darkens, binoculars show the 3rd-mag. star Deneb Algiedi, tail of the Sea-goat, about 3 degrees above the Moon. Note the beautiful earthshine on Moon's dark side.
As evening twilight ends (about 1-1/2 hours after sunset), find the Moon in SW, and the first mag. star Fomalhaut 18 degrees to Moon's lower left. Using binoculars, note the 3rd and 4th mag. stars Delta and Tau in Aquarius, 2.5 degrees apart and close to the Moon's left. A line from Delta to Tau extended 5 degrees upper right locates 6th-mag. Uranus about 2 or 3 degrees to Moon's upper right.
In today's afternoon and evening sky, look for the First Quarter Moon 90 degrees or one-quarter circle east of the Sun. Note the Moon's shape is half full. This phase of the Moon is ideal for using binoculars or a telescope to examine lunar surface details. That's because at the terminator (day-night boundary) at the center of the Moon's disk we see surface features illuminated by a low, rising Sun. Mountains cast long shadows, and craters look very deep. The Earth's revolution around the Sun at this time of year carries it away from Pisces (tonight's location of the First Quarter Moon) and toward the constellation Virgo, near the star Spica in the morning sky.
The Moon this evening is noticeably more than half full. As the sky darkens, note bright Mars 10 degrees to the Moon's east. Look again on Sunday night.
This evening, the Moon is nearly three-fourths full and has overtaken Mars. At nightfall note the Red Planet a few degrees to Moon's right, and the Pleiades star cluster about 14 degrees to Moon's lower left.
This evening, the Moon occults or covers some of the stars of the Pleiades cluster or its outlying members. Since the Moon is over 80 percent full and very bright, a telescope is recommended to view the occultations. Alcyone, of 3rd-magnitude, is the cluster's brightest star. It is covered by the Moon only from southeastern U.S., southeast of a line from the lower Rio Grande Valley of Texas to southeast Virginia. The area of visibility of Alcyone's occultation includes the TX Gulf Coast, the southeast halves of LA and MS, all of AL except the extreme northwest, nearly all of GA and NC, all of SC, and extreme southeast VA. From Miami the star is covered by the leading dark edge of the Moon at 8:39 p.m. EST, from Atlanta at 8:03 p.m. Atlas at mag. 3.6 is the cluster's second brightest star and father of the Pleiades, and marks the end of the handle of the tiny dipper-shaped group. Atlas is covered by the Moon's dark edge in the U.S. south of a line from southern CA (at dusk) through NV, UT, WY, SD, MN, northern WI, and northern MI, across Canada to the northern tip of ME. From East Lansing, MI, the star is covered at 9:52 p.m. EST. From the northwestern U.S., north of the line just described, only fainter outlying stars of 5th and 6th magnitude, southeast of the bright cluster core, are covered by the Moon.
As the evening progresses, use binoculars to watch the Moon gradually move slowly eastward, away from the cluster. The Moon will move through the Pleiades, covering more of its stars, on several occasions this year.
At dusk note the first-mag. star Aldebaran, eye of Taurus and follower of the Pleiades, 10 degrees to Moon's lower right. Also find the Pleiades cluster about 12 degrees to Moon's upper right, and Elnath, the Bull's northern horn, about 10 degrees to Moon's lower left. By Wednesday evening, the Moon will have passed Elnath.
From latitude 40 degrees north, this month's northernmost Moon passes within 12 degrees south of overhead nearly two hours before middle of night. Then it sets 38 degrees north of west about one hour before sunrise on Thursday morning, and rises 38 degrees north of east about 1-3/4 hours after sunset on Thursday.
Today Venus, overtaking the Earth, passes inferior conjunction, nearly between Earth and Sun. Viewing from Earth, the very thin crescent Venus appears just 5.5 degrees north of the solar disk and is very difficult to observe. (Within a week Venus will be easy to spot low in ESE shortly before sunrise.) In the opposite direction from the Sun, tonight's Full Moon rises well north of east shortly before sunset, passes 8 degrees south of overhead at 11:55 p.m., and sets well north of west shortly after sunrise on Saturday. The Moon is up all night, near the Gemini Twin stars Pollux and Castor. Watch the Moon shift its position in relations to these stars as the night progresses.
Around nightfall, about 1-1/2 hours after sunset, look for the Moon low in ENE with the Twins Pollux and Castor 9 and 13 degrees above, and Saturn 7 or 8 degrees below. Procyon in E and Sirius in ESE are also visible, far to Moon's right. As dawn brightens on Sunday, Moon and Saturn are only 3 or 4 degrees apart in the west.
At nightfall, Saturn is low in ENE, 17 degrees below Pollux, brighter of the Gemini Twins. Watch for the Moon rising 6 degrees to Saturn's lower left. Later tonight, when Saturn rises higher in the sky, binoculars will show the 4th-mag. star Delta in Cancer 0.6 degree to its south.
Three hours after sunset, look for Moon low in ENE with Saturn 18 degrees upper right, and Regulus, heart of Leo, 4 degrees to Moon's lower right. Regulus remains close to the Moon for rest of the night, until dawn on Tuesday.
During Jan. 18-Feb. 25, Saturn is within the quadrilateral of 4th and 5th-mag. stars Delta-Gamma-Eta-Theta in Cancer, which surrounds the Beehive cluster. This is an attractive field for binoculars!
Venus now rises in ESE an hour before sunrise and is easy to see as dawn brightens. At sunrise, Venus is 12 degrees to Sun's upper right, and binoculars reveal Venus as a crescent, a full arcminute across and just 2 percent illuminated. A 30-power telescope makes Venus appear as big as the Moon does with unaided eye, but of course their phases don't match today. On Saturday an hour before sunup, the star Spica in Virgo is 5 degrees to the Moon's east.
An hour before sunrise on Sunday, Spica will be 7 degrees to Moon's west. The Moon will then appear half full, as Last Quarter phase, 90 degrees west of the Sun. Note also bright Jupiter 16 degrees to Moon's east (left).
An hour before sunrise on Monday, the fat waning crescent Moon is just east of due south, with bright Jupiter 5 or 6 degrees to its upper left. Binoculars show the double star Alpha in Libra (mags 3 and 5, just 4 arcminutes apart), 1.5 degrees to Jupiter's right.
On Tuesday an hour before sunup, the Moon, a crescent one-third full, is in SSE with Jupiter 12 degrees upper right and Antares, heart of the Scorpion, 13 degrees lower left. Look again on Wednesday.
On Wednesday an hour before sunup, look for crescent Moon in SE to SSE with Antares closely above -- a beautiful sight for binoculars! Note the three planets Venus low in ESE, Jupiter well up in SSE to S, and Saturn low in W to WNW. Four solar system bodies, Venus-Moon-Jupiter-Saturn, span 158 degrees across the sky.
Moonrise on the next two mornings, on Thursday two hours before sunrise and on Friday about one hour before sunrise (as seen from lat. 40 degrees north) are the southernmost of this month. On Thursday Venus is 20 degrees upper right of rising Sun and shows a crescent 6 percent full.
Today about two hours after sunrise and Friday just over three hours after sunrise the Moon passes due south while just 21 degrees above the horizon (as seen from lat. 40 degrees north). On Friday morning, 45 minutes before sunrise, the old crescent Moon is low in SE with Venus 15 degrees to its upper left. They are unusually wide apart because Venus is well north of the ecliptic (Earth's orbital plane) and the Moon well south.
Tonight Saturn is at opposition as Earth passes between that planet and the Sun. From our vantage point on Earth, Saturn appears nearly 180 degrees from the Sun and is in the sky all night: Low in ENE at dusk, very high in S in middle of night, and low in WNW at dawn. Using binoculars in late evening, look for the 4th-mag. star Delta Cancri 1.2 degrees to Saturn's lower right, and the Beehive cluster in the same field to Saturn's upper left. Next week, Saturn, creeping west 5 arcminutes daily, passes the southern fringes of that cluster. An hour before sunrise on Sat. Jan. 28, Venus low in ESE and Jupiter approaching south are 60 degrees apart.
When Venus is a bright morning "star", it's easy to see in the daytime. Just find it in morning twilight and keep track of it until sunrise. For the next several weeks, binoculars will resolve the planet's crescent phase.
The Moon is New at 9:15 a.m. EST and won't be visible until early Monday evening.
Half an hour after sunset, the young crescent Moon is low in WSW.
As the sky darkens, the Moon is beautiful in binoculars, displaying earthshine on its dark side, and a scattering of 4th and 5th-mag. stars of Aquarius in the background.
Please send any comments, suggestions, or questions to
Thomas G. Ferguson:
fergus52@msu.edu
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