To the reader:
The Skywatcher's Diary for February 2001 has been prepared by
David Batch. 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 February issue, please send a long,
self-addressed stamped envelope to:
February 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
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Skywatcher's Diary: February 2001
The Moon sails by the bright outer planets, Jupiter and Saturn, over the next two nights. This evening the three objects line up, with Jupiter and the Moon lying nearly equidistant on either side of Saturn. The Moon passes First Quarter this morning at 9:02 am EST, so tonight it will appear slightly more than half illuminated.
If you are uncertain where to find Jupiter, the Moon points the way. Tonight the giant planet is 7 moon diameters above Luna. Use binoculars to examine both objects. Spot two bright craters on the Moon-Copernicus to the left of center and Tycho near the bottom. Can you detect any of Jupiter's moons?
Tonight the gibbous Moon sits 7 degrees (14 moon diameters) to the left of Aldebaran, the orange-tinted eye of Taurus, the Bull. Poised farther below the Moon is the prominent wintertime hunter, Orion. Look lower still-near the horizon-for Sirius, the brightest nighttime star.
Tonight the Moon punctuates the center of a great oval of bright winter stars known as the "Winter Ellipse." Trace through Rigel in Orion, Sirius in Canis Major, Procyon in Canis Minor, the Gemini Twins (Pollux and Castor), Capella in Auriga, and Aldebaran in Taurus.
The two bright stars a fist width to the left of the Moon this evening are Pollux and Castor, the Gemini Twins. Pollux is the lower sibling. The brothers are similar but not identical. Can you tell which shines brightest? Tomorrow night the Moon will be in line with the twins, 10 degrees (a fist width) below Pollux.
Venus, that spectacular dot in the WSW evening sky, sets 4 hours after the sun at our latitude-near the maximum allowable by law (physical law, that is). In a telescope the planet now appears just under half illuminated. To cut the contrast and make the planet's phase easier to see, look near sunset or earlier.
Today the Moon is closest to Earth for the year-221,738 miles. It was farthest on January 24-252,626 miles. The difference is an indication that the Moon's orbit is not quite circular. Photographs of the Moon taken at these two times show an apparent size variation, but detecting the difference in the sky is not likely.
The Moon was Full at 2:12 a.m. this morning-less than 10 hours after the Moon's closest approach of 2001. The tides today will, therefore, be highest for the year if all other factors are equal, particularly weather conditions. Once the sky gets dark, look for the bright star Regulus to the upper right of the Moon.
Look in the W at the end of evening twilight for the Great Square of Pegasus. It is composed of 4 stars similar in brightness to those of the Big Dipper. Each side of the square is slightly more than a fist width long. Venus currently aligns with the left (east) side of the square, a fist width below the corner.
Any morning an hour before sunrise Mars can be found in the S about 1/3 of the way up. It is 14 degrees to the upper left of Antares, the heart of Scorpius. The star's name means "rival of Mars" because its reddish color is similar to Mars'. Currently the planet is also the same brightness as Antares but will be noticeably brighter by month's end.
The "mean sun," a fictitious object we use in time keeping, is now farthest ahead of the apparent sun (the one we see) for the year. This difference, known as the Equation of Time, is 14 minutes today. That is how much you currently need to add to a sundial reading to convert to standard time.
Today the first ever controlled descent to the surface of an asteroid will
be attempted. The asteroid is a 21-by-8-mile rock known as 433 Eros. The NEAR
spacecraft has been orbiting the minor planet for the last year. NEAR was
launched in 1996. Today is the last day of the mission-the craft is not designed
for a soft landing. For more information on this historic event see http://near.jhuapl.edu/.
As night falls Jupiter and Saturn can now be found 2/3 of the way up in the SSW. Two outstanding star clusters flank Jupiter. To the upper right is the Pleiades, a small group that gets mistaken for the Little Dipper because of its shape. The Hyades is a looser and fainter grouping to the lower left. They include most of the stars in the "face" of Taurus, with the exception of Aldebaran. The Hyades are about 3 times closer to us than the Pleiades-150 and 410 light years, respectively.
Tomorrow morning the almost-last-quarter Moon sits only 2 degrees (4 moon diameters) above and slightly to the left of Mars. Look for the duo anytime after 3 a.m. until dawn. The next morning (Friday) the Moon is 8 degrees to Antares' upper left.
After spending winter evenings low on the northern horizon, the Big Dipper now begins its climb up the NE sky. At the end of dusk it stands on its handle in the NNE. The Pointers, the two stars in the end of the bowl, lead to Polaris, the North Star, about one "dipper length" away. The Big Dipper was known as the Drinking Gourd to slaves following the Underground Railroad. Under cover of darkness it led them north.
The two brightest planets, Venus and Jupiter, currently stand 52 degrees apart in the evening sky. By the end of the month the spread is 47 degrees, the minimum this time around. Next month Venus does a rapid descent toward the sun, disappearing from the evening sky at the end of March.
Over the next several mornings Mars will approach and pass within 1/4 degree of the 3rd-magnitude star Beta, in Scorpius. An hour before sunrise tomorrow Mars is 1.3 degrees to the star's right. The following morning Mars slides to within 0.8 degrees. Use binoculars to follow the progress.
Beta, in Scorpius, is a double star that can be split in small telescopes. The components are 3rd and 5th magnitude, separated by 14 seconds of arc (1/260 of a degree). Don't mistake it for the much wider pair of stars (Omega 1 and 2) one degree to Mars' lower left.
Tomorrow morning, Mars will be just 0.3 degrees to the right of the 3rd-magnitude star Beta, in Scorpius. The following morning Mars will be about the same distance on the other side (lower left) of Beta. Minimum separation (1/20 degree) occurs tomorrow evening 7 hours before Mars rises.
Mars currently moves half a degree (a moon width) per day against the background stars. By the end of the first week of March, Mars will stand overtop Antares, the brightest star in Scorpius. By May 11, Mars grinds to a standstill, 20 degrees to the left of Antares, before beginning retrograde.
Venus radiates at greatest brilliancy tonight. At magnitude -4.6 it shines 170 times brighter than a first-magnitude star. From a dark location after nightfall, see if you can detect your shadow cast by Venus on the snow. The planet is even observable during the middle of the day, with effort. Binoculars may help locate Venus and show its crescent shape.
Late February when the Moon is absent is the best time of the year to see the zodiacal light after evening twilight. Dark, clear skies are a must. Look for a large, faint, pyramid-shaped glow sitting on the western horizon, similar in brightness to the Milky Way. The effect is created by sunlight scattering off dust particles in the plane of the solar system
Leo, the Lion, and first of the "spring" constellations, is now above the eastern horizon after dusk. Its brightest star, Regulus, is 20 degrees (2 fists) up an hour and a half after sunset. The sight of Leo this time of year is reassuring. Spring will come.
Tonight is the first appearance (in North America) of the Moon after New. The thin crescent sits only 3 degrees above the horizon an hour after sunset. It is between the W and WSW. Start looking with binoculars as much as a half hour earlier. You need a flat, unobstructed view to the west.
The exquisite crescent Moon is 14 degrees (1 1/2 fist widths) to the lower left of Venus. Estimate where the Moon will be tomorrow night. It moves 13 degrees per day. The phase of Venus seen in a telescope or binoculars will match the Moon's. Observing Venus in bright twilight softens the contrast and makes the shape easier to pick out.
Venus is 11 degrees (a fist width) to the right of the Moon this evening. But look earlier, during the day, and you can use the Moon to find Venus in broad daylight. Mid-afternoon, when the Moon is due S, Venus is 11 degrees above and slightly to the right of Luna. Use binoculars, if needed, to initially locate the planet.
The bright star Capella, in Auriga, the Charioteer, is nearly overhead at the end of dusk. Capella, often called the "mother goat" star, is similar in temperature to our Sun. It is, therefore, the same color as Sol. Can you tell? Subtle, you say? It is the 4th brightest nighttime star.
The Moon and two giant planets line up this evening. Saturn is 11 degrees to the upper left of the Moon. Its rings are easily visible in a small telescope. They are tilted 23 degrees from edge-on. Can you see the shadow of the planet cast on the rings? Jupiter is 8 degrees to the upper left of Saturn.