Abrams Planetarium
SKYWATCHER'S DIARY:
May 1996
To the reader
The Skywatcher's Diary for May 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, together with mention of our Sky Calendar, would be appreciated.
A sample Sky Calendar for May 1996 is available over the Internet. It
can be viewed via a World-Wide Web browser such at Netscape or
Mosiac, directly at URL:
http://www.pa.msu.edu/abrams/may96skycal.html
If you would like a printed sample, send a long, self-addressed stamped
envelope to:
May Sky Calendar
Abrams Planetarium
Michigan State University
East Lansing, MI 48824
Each month, the Department of Physics and Astronomy at Michigan
State University also makes Skywatcher's Diary available over the
Internet. It can be accessed via a World-Wide Web browser such as
Netscape or Mosiac, directly at URL:
http://www.pa.msu.edu/abrams/diary.html
The Skywatcher's Diary is also available via anonymous ftp at:
www.pa.msu.edu in the directory /pub/swd
ftp://www.pa.msu.edu/pub/swd/
Lunar and Planetary Highlights for May
At dusk in early May, brilliant Venus is well up in WNW at dusk, and
sets more than 3-1/2 hours after sundown. Venus reaches peak
brilliance early in the month, and is unusually easy to see in the daytime,
especially just before sunset. If viewed at the same interval of time after
sunset each night, Venus sinks dramatically after mid-May. Venus
follows the Sun over the horizon by two hours on May 24, by one hour
on June 1, and by only half an hour on June 5. Venus shows striking
changes this month when seen through a telescope. In May through
July, Venus is close enough to Earth so that its crescent phase is
observable even through 7-power binoculars. The key is to observe
Venus in the daytime, or shortly after sunset, to avoid its brilliant glare
against a darkened sky. The last of a series of monthly evening pairings
of Venus and the Moon occurs on May 19.
Dawn skywatchers will find bright Jupiter in S while birds sing their
morning choruses an hour before sunup. A waning gibbous Moon is
nearby on May 7 and 8. A waning crescent Moon passes near Saturn
low in E to ESE at dawn on May 13.
Comet update: On Wednesday morning, May 1, Comet Hyakutake
passes only 21.4 million miles from the Sun; the comet has not
brightened as much as expected, and is too faint to be seen in the solar
glare. When it emerges into dark skies, it will be observable only from
southern latitudes and is expected to be of only 3rd magnitude and
fading. On May 1, Hyakutake begins its estimated 7,000-year journey
to the dark, cold outer end of its orbit some 30 times as far out as
Pluto's average distance from the Sun. What will Earth be like when the
comet returns some 14,000 years in the future?
-
- At dusk Venus is well up in W to WNW. First-magnitude reddish
Aldebaran, eye of Taurus, is 16 degrees to Venus' lower left. Mercury,
now faded to 2nd magnitude, is 14 degrees lower right of Aldebaran
and 24 degrees lower right of Venus. Aim binoculars at Mercury, and
you may glimpse the Pleiades star cluster 2 degrees to its upper right.
Note the 2nd-magnitude star Elnath, the Bull's northern horn, within
0.9 degree to Venus' upper right. Watch them separate in coming
nights, while both get lower as weeks pass. Early this evening the first-
magnitude star Spica is only 2 degrees south of the Moon. Watch them
separate as the night progresses.
-
- The Moon, approaching Full, can be spotted very low in ESE starting
about half an hour before sunset. This is the last evening you can see
both Sun and Moon simultaneously until May 18. As the sky darkens,
Spica is in SE, 15 degrees to Moon's upper right. Arcturus is in E,
about 33 degrees to their upper left. You can find both stars if you start
with the handle of the Big Dipper and "Follow the arc to Arcturus and
drive a spike to Spica."
On Friday morning for a few minutes after sunrise, try to see Sun and
Full Moon simultaneously. You'll need unobstructed views toward
ENE and WSW. If you don't succeed on Friday, try again on Saturday
morning.
-
- Tonight the Moon, now past Full, rises in ESE within about half an
hour after sunset. As sky darkens, the pair of 3rd-magnitude stars 9
degrees apart on a roughly horizontal line just above the Moon are
Zubenelgenubi and Zubeneschamali, the southern and northern claws of
the ancient Scorpion. These stars are now assigned to Libra the Scales
and are designated Alpha and Beta in that constellation. They'll be easier
to see next week, when the Moon rises later. These stars will help locate
the brightest minor planet (asteroid) Vesta.
-
- Venus reaches greatest brilliancy today but changes its brightness very
little for two weeks before and after. Just before sunset, try seeing
Venus with unaided eye in daylight; look 40 degrees to Sun's upper left.
A telescope or even a pair of binoculars will reveal Venus' crescent
shape, now 0.6 arcminute (1/100 of a degree) across and just over one-
fourth illuminated. Watch for changes in coming weeks as Venus
swings closer to Earth and presents less of its lighted side toward us.
The crescent will get thinner but larger in size.
Venus sets over 3-1/2 hours after the Sun from northern U.S., and 3
hours after from southern U.S. Tonight and Sunday, Venus' setting
place along your horizon is its northernmost of this century!
Three hours after sunset and rest of night, the reddish first-magnitude
star Antares, heart of the Scorpion, is 8 degrees to the Moon's south.
-
- Within an hour after sunset, use Venus as a guide to the soon-to-depart
bright winter stars. Aldebaran, eye of Taurus, is 18 degrees directly
below Venus. Capella, the Mother Goat Star, is 19 degrees to Venus'
upper right, while reddish Betelgeuse, shoulder of Orion, is 21 degrees
to Venus' lower left. Sirius, the Dog Star, 27 degrees to Betelgeuse's
lower left, and Procyon, 26 degrees to Betelgeuse's upper left, complete
the Winter Triangle with the famous red star. Keep a daily log, noting
which of these stars you can see.
-
- On Tuesday an hour before sunrise, find the waning gibbous Moon in
the south. The bright "star" about 9 degrees to Moon's lower left is
Jupiter.
-
- In Wednesday's predawn, as seen from Mexico and western U.S., the
waning gibbous Moon occults, or covers, Comet Hale-Bopp. Large
telescopes with specialized equipment at observatories in the Southwest
U.S. will be used to attempt to measure the size of the comet's tiny
nucleus as it emerges from behind the dark edge of the Moon. An hour
before sunup on Wednesday, look for Jupiter about 7 degrees to the
Moon's lower right.
-
- Find the brightest asteroid! About 2-1/2 hours after sunset, locate first-
magnitude Spica well up, a little east of due south. Some 21 degrees to
Spica's lower left is the 3rd-magnitude star Alpha Librae with equally
bright Beta 9 degrees to Alpha's upper left. Aim binoculars at Beta, and
the brightest asteroid, 5.6-magnitude Vesta, will be in the same field,
just 2.6 degrees to Beta's upper left. As a check, note the star Epsilon
Librae 2.0 degrees to Beta's lower left. At magnitude 4.9, Epsilon is
noticably brighter than Vesta.
Observe or photograph this star field on different nights, watching for
changes in Vesta's position among the stars. At the same time of
evening on May 20, Vesta will appear 4.0 degrees to Beta's upper right.
-
- An hour after sunset, the four brightest stars up are: Sirius, about to set
in WSW (look earlier to be sure to see it); Arcturus, halfway to
overhead in ESE; Vega, low in NE nearly 60 degrees lower left of
Arcturus; and Capella in NW 19 degrees upper right of Venus.
-
- If you have very dark skies and a telescope or fine pair of binoculars
such as 10x50's, here's a chance to get an early glimpse of what may
become next year's bright comet. Two hours before sunrise, locate
bright Jupiter in SSE. From Jupiter go 7-1/2 degrees left to the 5.0-
magnitude star 56 Sagittarii (56 Sgr). Next, look for a pair of 5th-mag.
stars half a degree apart and 3-3/4 degrees above 56 Sgr. The one on the
right is orange-colored 5.3-mag. 54 Sgr. The one on the left is 5.1-mag.
55 Sgr. As a check, there is also a 5.5-mag. star, SAO 162931, 0.7
degree upper left of 55 Sgr. The three stars form a triangle with 55 Sgr
at its obtuse angle.
On Sunday and Monday mornings, May 12 and 13, Comet Hale-Bopp
will pass near 54 Sgr, to the star's lower right in the sky. On Sunday,
the comet will be 9 arcminutes S of the star; on Monday 7.5 arcminutes
(1/8 of a degree) to the star's WSW. Day by day, the comet shifts to the
WNW (upper right) of 54 Sgr. It will be about 1 degree from 54 Sgr on
May 19 and 20, and nearly 2 degrees from it on May 25.
Comet Hale-Bopp on May 12 is 360 million miles from Earth, and 413
million miles from Sun, and glowing at 8th magnitude, unusually bright
for its large distance. By late in July, H-B will be an easier binocular
object well up in the southern sky at nightfall.
-
- On this date in 1983, Comet IRAS-Araki-Alcock passed within 3
million miles, the closest approach of a comet to Earth in this century.
On Sunday an hour before sunrise, the crescent Moon stands in the
ESE, with first-magnitude Saturn 14 degrees to its lower left.
-
- One hour before sunup on Monday, the Moon is very low, a little south
of due east. Look for Saturn about 2 degrees to Moon's lower right.
Telescopically, the rings of Saturn now appear 5 degrees from edge-on,
with their illuminated south face in view.
-
- An hour before sunrise on Tuesday, the old crescent Moon is very low,
just north of due east. Saturn is 13 degrees to its upper right.
-
- On Wednesday about 40 minutes before sunrise, the thin old crescent
Moon is just risen between E and ENE. If you're in the southern U.S.,
the Moon will be a little higher, and you can use binoculars to try for
faint Mars just rising 9 degrees to Moon's lower left.
-
- Last night Mercury narrowly missed passing in front of the solar disk,
missing the Sun's southern limb by about one-third of a degree. On
June 10th, Venus will come even closer, clearing the Sun's southern
limb by less than one-quarter of a degree.
-
- The Moon will be New on Friday at 7:46 a.m. EDT.
-
- There was no solar eclipse at this morning's New Moon, because the
Moon passed about 4 degrees south of the Sun. The Moon's shadow
missed the Earth completely, passing high over Antarctic regions.
-
- Half an hour after sunset, locate the slender crescent young Moon very
low, within 10 degrees N of due west and 15 degrees below Venus.
Don't wait much longer to look, or you'll miss it!
-
- Determine the clock time of your local midday, which is halfway from
sunrise to sunset. Then go outside 2 hours 5 minutes after midday
today, and you'll find Venus very high, due south. The altitude of
Venus above your southern horizon at that moment is equal to 117
degrees minus your latitude. (From latitude 40 degrees N, Venus would
appear 77 degrees up.) Note the crescent Moon 9 degrees below Venus
at midday; they'll keep company all afternoon as they move into the
western sky. At dusk they'll still be 9 degrees apart, with Venus to the
Moon's upper right. This is the final event in a series of monthly
evening Moon-Venus pairings.
Daytime is best for using a small telescope or even binoculars to observe
Venus as a crescent. Venus' disk is now 0.8 arcminute across, 14
percent illuminated. A magnification of 40x now makes Venus look
about the same size as the Moon does with unaided eye.
-
- At dusk Venus is 15 degrees to Moon's lower right. The Little Dog Star
Procyon is 18 degrees to Moon's upper left. As the sky darkens, note
the 2nd-mag. star Alhena (Gamma in Gemini) a degree or two below the
Moon. The sunlit crescent framing the earthlit remainder of the disk,
with star below, makes a beautiful sight for binoculars.
-
- At dusk, Procyon is 11 degrees to Moon's lower left. The Gemini
twins, Pollux and Castor, are 12 to 16 degrees to Moon's upper right.
-
- Two hours after sunset, a line connecting the Gemini twins in WNW
points to the Moon in the west. Binoculars show the Beehive star cluster
7 or 8 degrees to Moon's upper right.
-
- Venus now sets just over 2 hours after the Sun, from northern U.S. By
June 2 it will set only one hour after sunset. On what June date will you
last see Venus in the evening sky?
-
- An hour after sunset the Moon is well up in SW to WSW, with
Regulus, heart of Leo the Lion, 5 degrees to Moon's upper right. The
Moon is approaching First Quarter and is not quite half full. This
weekend is ideal for using binoculars and small telescopes for seeing
lunar surface features.
-
- Locate the Moon in SW an hour after sunset. Tonight Regulus is 11
degrees to Moon's upper right. The Moon has passed First Quarter
phase (where it was 90 degrees or one-quarter circle east of the Sun),
and now appears slightly more than half full.
-
- At sunset Venus appears 21 degrees to Sun's upper left. The thinning
crescent Venus, now only 7 percent full, appears large enough to reveal
its shape when observed through 7-power binoculars. The key is to
look in daylight or in bright twilight, before the tiny brilliant crescent
contrasts too much with the darkening sky. An hour after sundown
Venus is very low in WNW.
-
- One-and-a-half hours before sunrise these mornings, Saturn appears as
a first-magnitude "star" about 10 degrees up and 10 degrees south of
east. The rings are tipped nearly 5-1/2 degrees from edgewise, with
their illuminated south face in view. Saturn rises about 2 hours earlier
each month, and by late September it will rise at sunset and be up all
night.
-
- An hour after sunset the waxing gibbous Moon is in south, with Spica,
the spike of wheat or ear of corn in Virgo's hand, about 5 degrees to
Moon's lower left.
-
- The Moon is in SSE at dusk, with Spica about 9 degrees to its upper
right.
-
- An hour after sunset Venus is only about 3 degrees up and 30 degrees N
of due west. In coming days, you'll need to look earlier in the evening
to spot Venus before it sets.
-
- An hour after sunset the nearly full Moon is in the SE. About 11 degrees
below it note the reddish star Antares, heart of the Scorpion. Near the
end of May each year, this star is at opposition and is up nearly all
night. In the opposite direction, Aldebaran, eye of Taurus, is hidden at
conjunction on the far side of the Sun.
-
- Remember to look early for Venus! Half an hour after sunset it's about
5 degrees up and 30 degrees north of west. The Full Moon is then rising
into the southeast. As the sky darkens, look for Antares, heart of
Scorpius, 10 degrees to the Moon's right and a little higher. This
Strawberry or Rose Moon is the first of two Full Moons this month.
-
- At sunset, as soon as the Sun's disk has slipped below the horizon, use
binoculars to search for the very thin 2 percent crescent Venus within 12
degrees upper left of Sun. Do not look at the Sun through binoculars!
By an hour after sunset, the Moon has just risen in ESE. Wait another
two hours, and you'll see bright Jupiter 15 degrees to Moon's lower
left.
-
- Three hours after sunset, the waning gibbous Moon is very low in ESE
to SE, with Jupiter just 4 degrees to its lower right. Moon and Jupiter
keep company for the rest of the night, remaining 4 or 5 degrees apart
until dawn on Tuesday.
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