To the reader:
The Skywatcher's Diary for August 1998 has been prepared by
Robert C. Victor. 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 August issue, please send a long,
self-addressed stamped envelope to:
August 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
ftp://www.pa.msu.edu/pub/swd/
Giants rise in evening! Jupiter, gleaming with rare brilliance, rises just
south of due east, two hours after sunset in a dark sky on Aug. 1, and
40 minutes after sunset (around middle of evening twilight) on Aug. 31.
Saturn rises late in evening, about 1-1/2 to 1-3/4 hours after Jupiter
does. Watch for a bright "star" rising north of east, far lower left of
Jupiter.
For rest of the night, Saturn trails Jupiter across the sky, 36 to 38
degrees E of the giant planet and three magnitudes fainter. Diary entries
for the nights of Aug. 9-13 decribe the arrangement of Moon, Jupiter
and Saturn at various times of the night. Jupiter at dawn is well up in
SSW at start of August and drifts lower into WSW as month
progresses. Saturn is very high at dawn, crossing from SE through S
toward SW during month, nicely placed for telescopic viewing. Saturn's
rings are tipped nearly 17 degrees from edge-on, our best view this
year.
Other planets at dawn: Brilliant Venus on Aug. 1 rises nearly 2 hours
before sunrise, or just before first light of dawn. Faint Mars appears
very close by in first week, passing within 0.9 degree on Aug. 4 & 5,
and ends month 15 degrees upper right of Venus. Watch for straight
lineup of Venus-Pollux-Castor on Aug. 11 & 12; and of Mars-Pollux-
Castor on Aug. 17 & 18. Moon passes near Venus and Mars on Aug.
19 & 20. By Aug. 23, Mercury (mag. +1.7) can be spotted within 5
degrees lower right of Venus. Use binoculars. Mercury brightens
rapidly in next week, to mag. +1 by Aug. 26 and mag. 0.0 by Aug. 30.
Once Mercury is easily seen at dawn in the last days of August, all five
naked-eye planets can be simultaneously viewed in morning twilight.
The best time to look may be about one hour before sunrise. On Aug.
27 & 28 Mercury passes 2.3 degrees S (right) of Venus. Mercury
appears highest on Sept. 1, as it widens to a maximum distance of 2.9
degrees upper right of Venus. Mercury will brighten further in early
September and form a very compact grouping with Venus and Regulus,
an impressive sight for binoculars. Details will appear in our Sky
Calendar and Skywatcher's Diary for September.
Skywatcher's Diary: August 1998
Milky Way Legacy concludes this weekend at Abrams Planetarium.
Tour our amazing home galaxy with noted author Ken Croswell and
emerge with a clearer view of our home in space. Find out some of the
ways the Milky Way is very special, and how, unlike most galaxies, it
is equipped to create the variety of ingredients needed for life.
Final showings are Fri. July 31 and Sat. Aug. 1 at 8 p.m., and Sunday
Aug. 2 at 4 p.m.
Also this Friday and Saturday, July 31 and August 1, MSU
Observatory will be open for public viewing from 9:00 until 11:00 p.m.
if skies are clear.
The Moon, two-thirds full, is in SSW an hour after sunset, with
Antares, heart of Scorpius, about 15 degrees to its lower right. Between
Moon and Antares lies a nearly vertical line of three stars, the Scorpion's
head.
An hour before sunrise on Sunday, brilliant Venus is very low in ENE,
with faint Mars 1.7 degrees lower left. Watch for changes in next few
mornings. Look also for Pollux and Castor, the Gemini twins, 9 to 11
degrees to Venus' left, and Orion in E to ESE.
The final presentation of our family show, WSKY ... Radio Station of
the Stars, is today, 2:30 p.m. at Abrams Planetarium.
The Moon, three-quarters full, passes south soon after sunset. As sky
darkens, look for Antares, heart of Scorpius, 9 degrees below the
Moon.
An hour before sunup Monday, Venus is very low in ENE; Mars is 1.2
degrees lower left.
An hour after sunset, the Moon is in the southern sky, with Antares 15
degrees lower right.
An hour before sunrise on Tuesday and Wednesday, brilliant Venus
and faint Mars, very low in ENE, are at their closest, 0.9 degree apart.
Mars is to Venus' north (left or upper left). Two other naked-eye
planets: Bright Jupiter well up in SSW, and Saturn high in SE.
The Teapot of Sagittarius is in the south two hours after sunset, but the
Moon's presence just 6 degrees above the top of the lid will prevent
observation of the Sagittarius Milky Way. Wait until at least Aug. 11,
when the Moon won't be up yet at that hour.
An hour before sunup on Thursday, brilliant Venus is very low in ENE
with faint Mars within 1.2 degrees above. Pollux is within 7 degrees
upper left of the pair, and Castor 4-1/2 degrees above Pollux. Watch the
changing configuration of these four bodies in coming days. Venus-
Mars will still be only 2 degrees apart on Saturday.
Half an hour before sunset, Sun and Moon are simultaneously visible,
low in sky in nearly opposite directions. An hour before sunrise on
Friday, look low in ENE for brilliant Venus with faint Mars 1.6 degrees
above.
A few minutes before sunset, as the Sun rests on WNW horizon, look
in the exact opposite direction to see the Full Moon, just risen. You'll
need unobstructed views toward WNW and ESE to see both Sun and
Moon simultaneously. August's Full Moon was known to Algonquin
Indians and colonial Americans as the Green Corn Moon. Tonight the
Moon is up all night, setting about half an hour after sunrise on
Saturday.
About half an hour after sunset from northern U.S. (a little later from
southern U.S.), look for Moon just risen 15 to 20 degrees S of due east.
Note the Moon's reddish color when it's rising, caused by the scattering
out of the bluer light by Earth's atmosphere. Next week, as seen from
the latitude of Massachusetts, through lower Michigan, to southern
Oregon, the Moon rises some 35 to 40 minutes later and about 6
degrees farther north nightly. For southern U.S. the nightly delay of
moonrise time is a few minutes longer.
Two hours after sunset, the waning gibbous Moon is low in ESE, with
bright Jupiter trailing within 13 degrees to its lower left. An hour before
sunup on Monday, they're high in SSW to SW, with Jupiter some 9
degrees to Moon's upper left. Also in the morning, look for Saturn high
in SSE, 36 degrees to Jupiter's upper left, and for brilliant Venus very
low in ENE. Faint Mars, 3 degrees to Venus' upper right on Monday
morning, is passing within 6 degrees lower right of Pollux, the brighter
of the Gemini twins. Castor, the other twin, is 4-1/2 degrees upper left
of Pollux.
Two hours after sunset, the waning gibbous Moon is very low, a few
degrees south of due east, with bright Jupiter 2 or 3 degrees to its upper
right. By an hour before sunup on Tuesday, Moon and Jupiter will be
high in SSW, some 5 or 6 degrees apart.
Tonight the Moon rises just north of east, within 2-1/2 hours after
sunset from northern U.S. Wait an additional hour, and you can see
two planets flanking the Moon: Bright Jupiter 17 degrees to Moon's
upper right, and Saturn 19 degrees to Moon's lower left. By an hour
before sunup on Wednesday, the long line of three bodies is high in the
southern sky, with the Moon just over halfway from Jupiter toward
Saturn.
Tonight the interval from nightfall until moonrise will provide a
"window" of very dark skies without twilight or moonlight, excellent
for viewing the Perseid meteor shower if you're away from the lights of
civilization. Meteors can flash into view anywhere in the sky, but
members of the shower, if their paths are extended backward far
enough, will streak away from an area in the northeast sky in the
constellation Perseus, below the "W" of Cassiopeia. The Moon. two-
thirds full, rises within three hours after sunset (from northern U.S.),
brightening the sky for the rest of the night, and reducing the number of
faint meteors visible. The Moon keeps close company with Saturn for
the rest of the night, until dawn on Thursday. Low in ENE at dawn on
Thursday, Venus and Mars have spread to 5 degrees apart.
Four hours after sunset, the Moon is very low, 10 degrees N of due east
and 10 degrees lower left of Saturn. Approaching Last Quarter, the
Moon is still slightly over half full.
One-and-a-half hours before sunup on Saturday, the fat crescent Moon,
high in ESE, is nearly half full. Look for the Pleiades star cluster 10
degrees to Moon's upper left, and first-magnitude Aldebaran, eye of
Taurus, about as far to Moon's lower left. Binoculars give a fine view of
the Pleiades, and also of the V-shaped hyades cluster near Aldebaran.
One-and-a-half hours before sunup on Sunday, the Moon is one-third
full in E to ESE. Aldebaran, reddish eye of Taurus, is some 4 degrees
to Moon's upper right, while stars of the Hyades, forming rest of the
Bull's head, lie closely above and upper right of Aldebaran.
An hour before sunrise on Monday, between E and ESE, find the
waning crescent Moon, with Betelgeuse, shoulder of Orion, 11 degrees
to its lower right. Some 10 degrees right of Betelgeuse, look for Orion's
belt, a vertical line of three stars less than 3 degrees long. Rigel, Orion's
bright foot, is 9 degrees to the right of the belt. Watch for the rising of
Sirius, the Dog Star, which can be found by extending Orion's belt
downward 22 degrees toward the ESE horizon. Procyon low in the east
completes the nearly equilateral "Winter Triangle" with Betelgeuse and
Sirius.
An hour before sunup on Tuesday, the waning crescent Moon is nearly
due east, with brilliant Venus low in ENE, 25 degrees to Moon's lower
left. Mars is between them, 8 degrees to Venus' upper right. On
Tuesday morning the Moon is nearly encircled by five bright objects,
each 16 to 18 degrees away: In clockwise order, they are Betelgeuse to
Moon's right, Procyon below the Moon, Mars to Moon's lower left, and
Pollux and Castor, the Gemini twins, to Moon's left.
On Wednesday an hour before sunup, the thin crescent Moon is low, N
of east, with brilliant Venus 13 degrees to its lower left. Faint Mars is 8
degrees upper right of Venus and about 6 degrees to Moon's lower left.
Look for Procyon 12 degrees to Moon's lower right, and Pollux and
Castor, the Gemini twins, 10 and 15 degrees to Moon's upper left.
Thursday morning will be your last chance to see the old Moon of the
current lunar cycle. An hour before sunrise, look very low in ENE for
the thin crescent with Venus 3 degrees to its upper left. Faint Mars is
within 9 degrees upper right of Venus and a similar distance lower right
of Pollux.
The Moon will be New on Friday at 10:13 p.m. EDT. An annular (ring)
solar eclipse will be seen from some islands in and around Indonesia.
After this morning's old crescent, the Moon can next be seen as a young
crescent early on Sunday evening.
On Saturday an hour before sunrise, find brilliant Venus very low in
ENE and then locate faint Mars 10 degrees to its upper right and 10
degrees below Pollux. On Saturday morning and early next week, you
can also locate Mars by extending a straight line from Sirius (very low
in ESE) through Procyon (low in E) to Mars.
Each year around this date, the star Regulus, heart of Leo, appears
almost directly behind the Sun. In two to three weeks, Regulus emerges
into the morning sky, this year appearing very close to Venus and
Mercury Sept. 6-8. Stay tuned!
About 20 or 30 minutes after sunset, the almost two-day-old crescent
Moon is nearly due west, very low. Binoculars give the best view of the
thin young crescent.
For the first few nights of its current cycle, the Moon sets less than half
an hour later each evening from northern U.S. Thirty minutes after
sunset tonight, the Moon is easy to see, low, south of west. By an hour
after sunset, it has nearly set, due west. Look nightly, and you'll notice
the Moon is waxing, or growing thicker from night to night, as it moves
farther from the Sun in the sky.
An hour before sunrise on Tuesday, aim binoculars toward Venus very
low in ENE and look for Mercury 3 degrees to its lower right. Mercury
will appear higher each morning for another week and brighten, and by
this week's end will climb higher than Venus.
An hour after sunset, look low in WSW for first-magnitude Spica 8
degrees lower left of the waxing crescent Moon. This star will disappear
into the twilight glow in September.
An hour before sunrise on Wednesday, binoculars help locate Mercury
just 2.5 degrees lower right of Venus, low in ENE twilight glow. From
then until Sept. 15, Mercury will stay within 3 degrees of Venus.
An hour after sunset, crescent Moon is in WSW with Spica 7 degrees
below. Jupiter is just rising 5 degrees S of east.
An hour before sunup next two mornings, very low in ENE, Mercury
appears 2.3 degrees S (right) of Venus. Dim Mars appears 13 degrees
upper right of the pair. Two additional planets are visible, bringing the
total to all five naked-eye planets visible simultaneously! They are bright
Jupiter in SW, and Saturn high in SSW.
An hour before sunup on Friday, Venus and Mercury are still 2.3
degrees apart very low in ENE, their closest until they come even closer
in September's second week. In the two weeks from now until then, all
five naked-eye planets can be viewed simultaneously!
With the Moon near half full, this weekend is ideal for observing the
Moon with binoculars or a small telescope. Look for craters and other
lunar surface features, especially near the Moon's terminator (day-night
boundary), where long shadows are cast.
An hour before sunrise on Saturday, Mercury has climbed higher than
Venus, and appears 2.4 degrees to Venus' upper right. Look very low in
ENE; binoculars give the best view.
An hour after sunset, look in SSW to find Antares, heart of Scorpius,
10 degrees lower left of the half-illuminated Moon. The Scorpion's head
is marked by a vertical, slightly curved line of stars 4 to 7 degrees below
the Moon, which is at First Quarter phase tonight.
An hour before sunup on Sunday, find brilliant Venus very low in
ENE, with Mercury 2.6 degrees to its upper right. Mars is now nearly
15 degrees upper right of Venus. Bright Jupiter is in SW to WSW, and
Saturn is in SSW, 38 degrees to Jupiter's upper left.
This evening the Moon is slightly gibbous (more than falf full), with the
red supergiant star Antares in SSW, 11 degrees to its lower right.
An hour before sunup on Monday, Mercury reaches greatest elongation,
18 degrees from Sun. Although very low in ENE, it's easy to find, just
2.8 degrees upper right of Venus.
An hour before sunrise on Tuesday and Wednesday, Mercury reaches a
maximum distance of 2.9 degrees upper right of Venus. After
Wednesday, the gap between the planets will narrow until Mercury
passes just 0.4 degree left of Venus on Sept. 11. Binoculars give the
best views of the pair of inner planets. Look low, between ENE and E.
