To the reader:
The Skywatcher's Diary for April 2000 has been prepared by
D. 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 April issue, please send a long,
self-addressed stamped envelope to:
April 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
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Skywatcher's Diary: April 2000
The three bright outer planets are putting on a show low in the west, an hour after sunset. Jupiter is brightest and the middle of the trio. Saturn is 6 degrees to the upper left. Mars is only 2 degrees to Jupiter's lower right and much fainter. Mars' position relative to Jupiter will noticeably change over the next several nights, passing to Jupiter's right on April 5.
Try to catch the thin old Moon thirty minutes before sunrise this morning. Mercury is 2 degrees to the Moon's upper left, and Venus 10 degrees due left. The challenge will be easier for those in the southern states.
Daylight Saving Time goes into effect at 2 a.m. for most of the U.S.
Sirius, the brightest nighttime star, shines in the SSW an hour after sunset. The only brighter object then visible is Jupiter lower in the west. The planet outshines Sirius by only half a magnitude. A rule of thumb often repeated is that stars twinkle and planets do not. Try to confirm or refute the adage.
New Moon occurs at 2:12 p.m. EDT. The absence of moonlight all night provides a good opportunity to observe under extremely dark conditions. The winter Milky Way beckons.
Tonight Mars is only 1 degree (two Moon diameters) to the right of brilliant Jupiter. The young crescent Moon can be glimpsed 9 degrees below the pair. Timing is important to be able to see the Moon. 45 minutes after sunset is optimal, but start looking earlier. Seek out a low western horizon, and use binoculars to help spot the thin Moon.
A rare and beautiful sight awaits skywatchers this evening. The three brightest outer planets and the 2-day-old Moon produce a striking arrangement in the western sky as dusk settles in. Saturn is 3 degrees (six Moon diameters) to the right of the Moon. Jupiter, the brightest of the three planets, is twice the Moon-Saturn distance (6 degrees) to the lower right of Saturn. Mars, the faintest of the objects, is only 1 degree to the upper right of Jupiter.
An hour after sunset tonight the crescent Moon is 9 degrees to the lower right of the orange star Aldebaran, the eye of Taurus the Bull, and 15 degrees to the upper left of Saturn. The Pleiades star cluster makes a good binocular target, 9 degrees to the right of the Moon.
Tonight the crescent Moon is 6 degrees above Aldebaran, the eye of the Bull. Orion's Belt, three equally-spaced, equally-bright stars, is about 20 degrees to the Moon's left.
Today is National Astronomy Day, a time when many organizations involved with public astronomy hold observing sessions and other activities open to all. Check with your local planetarium, observatory, or astronomy club to see what is offered in your area and join the fun.
At the end of evening twilight the crescent Moon is near the center of the Winter Ellipse, or Winter Hexagon, a large figure made by tracing through the bright stars in Canis Major, Canis Minor, Gemini, Auriga, Taurus, and the foot of Orion.
Tomorrow morning the Moon reaches First Quarter phase at 9:30 a.m. EDT. Look early this evening and try to detect that the Moon is less than half illuminated. Look again tomorrow night to confirm that First Quarter has passed.
The Moon is in line with the Gemini twins this evening, and 9 degrees to the lower left of Pollux, the brighter and leftmost twin. Procyon, the brightest star in Canis Minor, the Lesser Dog, is 16 degrees below the Moon.
An hour after sunset the three evening planets form a pleasing isosceles triangle low in the west. Jupiter and Saturn create the base, while Mars stands at the apex.
The gibbous Moon stands high in the south an hour after sunset. Six degrees to the Moon's right is a faint collection of stars known as the Beehive Cluster or Praesepe. Normally the cluster is visible to the unaided eye as a smudge of light in a clear, dark sky. The Moon's presence guarantees a pair of binoculars will be needed to find Praesepe tonight.
Regulus, the heart of Leo the Lion, is 3 degrees below and slightly left of the Moon tonight an hour after sunset. The Moon will appear among the stars of the constellation Leo for the next two nights but to the east and lower each evening.
The trio of planets in the west--Mars, Jupiter, and Saturn--form their most compact visible arrangement tonight and tomorrow night. The planets are within a 5-degree spread. The last time these three outer planets appeared this close together was 1901, and the event will not occur again until 2080.
The most compact grouping of Mars, Jupiter, and Saturn, in a 179-year interval continues tonight. Look an hour after sunset low in the west.
The Moon is 9 degrees below and to the right of the 2nd magnitude star Denebola, marking the tail of Leo the Lion.
An hour after sunset Mars, Jupiter, and Saturn can be found very low in the WNW. The three planets form a right triangle with Saturn at the 90-degree angle, Mars to the upper right and Jupiter to the lower right, almost on the horizon.
The Moon, one day before Full, shines in the ESE an hour after sunset. Although not yet Full, the Moon will seem so to the casual observer. Spica, the brightest star in the constellation Virgo, appears 7 degrees to the Moon's lower right.
The Moon is Full at 1:41 p.m. EDT today. The fourth Full Moon of the year was sometimes called the Planter's Moon or Egg Moon by American colonists. The Moon rises as the sun sets tonight and so will be visible all night long.
The reign of the three bright outer planets, that have held starwatchers' attentions for the last several months, is coming to an end. Jupiter currently sets an hour after sunset, followed closely by Saturn and Mars. The focus now becomes how many more days can they continue to be seen before disappearing into the sunset glare. Tonight look low in the west 45 minute after sunset. Binoculars will be helpful.
The Moon is visible for the next twelve days every morning at dawn. Early risers can follow the waning Moon's journey through the zodiac constellations of Libra, Scorpius, Sagittarius, Capricornus, Aquarius, and Pisces.
The Lyrid meteor shower peeks tonight, but the bright gibbous Moon will inhibit sightings. Try looking after about 10 p.m. until the Moon rises, around 11:30 p.m. This shower has an erratic history, with occasional bursts of activity, although don't expect more than one meteor per minute at best.
An hour before sunrise this morning the Moon is in the SSW, 8 degrees to the upper left of the bright reddish star Antares, the heart of Scorpius. Antares is a red supergiant star hundreds of times larger than the sun, in the latter stages of its evolution.
The evening trio of Jupiter, Saturn, and Mars are a challenge to spot low in the WNW. Jupiter sets first, 45 minutes after the sun, followed by Saturn, 15 minutes later and Mars, 30 minutes after Saturn. Use binoculars.
Before dawn the Moon can be found among the stars of Sagittarius, above the pattern nicknamed the "Teapot." This figure is a familiar sight low in the south on a summer's eve. It also roughly marks the direction toward the center of our Milky Way galaxy.
Orion, a familiar evening fixture all winter long, is now low in the west an hour after sunset and will soon be lost in twilight. The three "belt" stars are parallel to the horizon, pointing the way to Taurus the Bull 22 degrees to the north and the bright star Sirius the same distance to the south. Mars and Saturn may still be glimpsed with binoculars low in the WNW.
The Moon passes Last Quarter phase between this morning and tomorrow morning, exactly at 3:30 p.m. today. Try to confirm that the Moon is more than half illuminated this morning and less than half tomorrow morning. Use binoculars if doubtful. For late risers the experiment can be carried out in morning daylight, since the Moon is in the sky until about noon.
Summer is clearly on its way, marked by the appearance of Vega, the first of the bright stars that comprise the Summer Triangle. Look low in the NE an hour and a half after sunset. On mid-summer evenings Vega stands nearly overhead.
The crescent Moon makes a wonderful target for binoculars. Find it low in the ESE an hour before sunrise. By 9 a.m. EDT the Moon is due south.
Orion has one foot in the grave, so to speak. Rigel, the bright star that marks the foot of Orion, sets an hour and twenty minutes after sunset, before the end of twilight. The rest of Orion will soon follow, as the summer stars take over.
In ancient times today was known as one of the four cross-quarter days that marked (approximately) the interval between the solstices and equinoxes. The modern May Day observance can trace its roots to this cross-quarter day.