Abrams Planetarium
SKYWATCHER'S DIARY: August 1996
To the reader
The Skywatcher's Diary for August 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 (Sept 96) is available over the Internet.
It can be viewed via a World-Wide Web browser such at Netscape
or Mosaic, directly at URL:
http://www.pa.msu.edu/abrams/sep96skycal.html
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 Mosaic, 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/
Celestial Highlights for August
Comet Hale-Bopp, dimly visible to the unaided eye from very dark
sites, is on track to become next year's Great Comet. In early August it
attains its greatest altitude in our night sky within a timespan three
millennia past and future. The Perseid meteor shower peaks on the night
of August 11-12 with no interference from moonlight. Brilliant Venus in
August-September reaches its highest position in the eastern morning
sky for this year, and in September's first week, Venus passes 3 deg S of
Mars.
Jupiter dominates the evening. Look in SSE at dusk in early August, in
S in September. Saturn at the start of August rises in east about two
hours after sunset and stands well up in SSW at dawn. The planet rises
earlier each week until late September, when it rises at sunset and is up
all night.
Comet expert and MSU Alumnus Charles S. Morris at NASA's Jet
Propulsion Laboratory has issued a new brightness forecast for Comet
Hale-Bopp from now until its perihelion on March 31 next year, and it
is good news! The comet already exceeds 6th magnitude. Since Earth
temporarily recedes from Comet Hale-Bopp during August through
October, it brightens slowly at first, to mag. 5 in September, and to
mag. 4 sometime in November. At the turn of the year, as the comet
sinks into the western twilight glow and emerges into the eastern
morning sky, Morris predicts it will glow at 3rd or 2nd magnitude.
In 1997, from January well into March, Comet Hale-Bopp brightens in
E to NE predawn sky as it closes in on both Earth and Sun. Back in
NW evening sky in late March, Hale-Bopp is expected to peak in
brightness, between mag. -0.5 and -2.0, according to Morris. But he
cautions, quoting from his very good friend, comet discoverer-
observer, and writer David Levy: "Regarding people who insist that
[Hale-Bopp will be very bright in 1997]: Comets are like cats. They
have tails, and they do precisely what they want."
Comet Hale-Bopp in August 1996 is a hazy patch of light, 6th-
magnitude or brighter, visible through binoculars, telescopes, and with
unaided eye in very dark skies. The keys to locating it in August are the
stars Nu and Mu in Ophiuchus. A finder chart appears on the Abrams
Planetarium Sky Calendar, or you can get to it via the following star-
hop: Begin with 1st-mag Antares in SSW at nightfall. Next, find 2.4-
mag Eta Oph 14 deg upper left of Antares. Then, find 3.3-mag Nu Oph 13 deg
upper left of Eta, and 4.6-mag Mu 5-1/2 deg upper right of Nu and 10 deg
upper left of Eta. Both Nu and Mu can be viewed together within the
field of 7-power binoculars. (A line from Antares to Eta Oph extended
10 deg past Eta ends very near Mu.) In early August the comet passes
closely above Nu, and later in month closely above Mu, as described
under entries in the Skywatcher's Diary below.
Comet Hale-Bopp is inbound toward perihelion, 0.914 astronomical
units or 85 million miles from Sun on March 31, 1997. For several
weeks before and after, it could put on a very impressive display! This
summer, astronomers are hoping for a continuing increase in brightness
as H-B comes closer to Sun and its water ice vaporizes ever more
vigorously. The comet's distance from Sun shrinks from 3.5 a.u. on
Aug 3, to 3.0 a.u. on Sept 21, 2.5 a.u. on Nov 2. Even as the comet
approaches Sun, planet Earth for nearly three months pulls away from
H-B: During Aug 2-Oct 28, the comet's distance from Earth widens
from 2.73 a.u. to 3.05 a.u. (254 to 284 million miles).
In September and October 1996, Comet H-B will linger near the 4.5-
mag star SAO141665. A sample copy of our September Sky Calendar
with a detailed all-sky map and comet finder on the reverse side can be
obtained by sending a long, self-addressed stamped envelope to:
September Sky Calendar
Abrams Planetarium
Michigan State University
East Lansing, MI 48824
For more on Hale-Bopp, visit the Websites:
http://encke.jpl.nasa.gov/hale_bopp_info.html
http://www.skypub.com/comets/comets.html
-
- You can see the Moon and as many as all five anciently known planets
overnight, if you first succeed with the hardest one during evening
twilight: Within 40 minutes after sunset, look very low, between W and
WNW, for Mercury with fainter Regulus 1 degree to its lower right.
Observers in northern states would do well to see just Mercury, even
with binoculars. From southern states and the Southwest, Mercury may
be seen with unaided eye, but Regulus will require binoculars. From
Hawaii, both are visible with unaided eye.
The other four planets are easy: Bright Jupiter is in SSE at dusk and
passes due S 2-1/2 to 3 hours after sunset. By then Saturn has risen in
E, 19 degrees lower left of waning gibbous Moon.
By Friday an hour before sunup, Saturn is well up in S, to Moon's
upper left. Brilliant Venus is then in E, with faint Mars 10 degrees to its
lower left. A telescope shows Saturn's rings tipped 6 degrees from
edgewise, and Venus as a fat crescent.
-
- About two hours after sunset, watch for the Moon rising nearly due
east. Another hour later, look for Saturn within 5 degrees to Moon's
lower left. One to 1-1/2 hours before sunrise on Saturday, look high in
south for Saturn 2 to 3 degrees to Moon's lower left.
-
- Beginning tonight, the Moon rises late enough to allow a brief
"window" of dark moonless skies for seeing Comet Hale-Bopp. As
soon as the sky gets very dark (about 1-1/2 hours after sunset,
depending on your latitude), locate the reddish first-magnitude star
Antares in SSW, 30 degrees right of brilliant Jupiter. Next, find the 2.4-
mag star Eta in Ophiuchus 14 degrees upper left of Antares. Eta should
be easy to spot, since there's no star as bright very nearby. Then, find
the 3.3-mag star Nu 13 degrees upper left of Eta. Tonight through
Monday, Comet H-B is about 2 degrees upper left of Nu. If you're in a
dark place, can you see the comet with unaided eye? Through
binoculars, it should be easily visible as a hazy patch of light of about
mag 5-1/2. The comet is now moving WNW (to upper right) by about
1/3 of a degree per day, and will appear closest to Nu Ophiuchi August
7 and 8.
When the Moon finally rises (about 2-1/2 hours after sunset from
northern U.S.), look for Saturn 10 degrees to its upper right. One to 1-
1/2 hours before sunup on Sunday, Saturn is high in south, 12 degrees
to Moon's right.
-
- Tonight about 1-1/2 hours after sunset, as the sky gets very dark, locate
bright Jupiter east of due south, and Antares, heart of Scorpius, 30
degrees to Jupiter's west. Comet Hale-Bopp is now 17 degrees to
Jupiter's upper right and 2 degrees upper left of the 3.3-mag star Nu in
Ophiuchus.
Although Comet Hale-Bopp approaches the Sun until March 31, 1997,
Earth's orbital motion is now temporarily carrying us away from the
Comet. On Aug. 2 Comet H-B was 254 million miles from Earth; by
Oct. 28 it will be 30 million miles farther from us. Even so, the comet is
expected to brighten slowly as it approaches Sun and becomes more
active.
-
- In early August at nightfall, the Milky Way is in fine view. Begin by
facing east and finding the Summer Triangle: Nearly overhead is bright,
bluish Vega, with first-mag Altair in SE 34 degrees to Vega's lower
right, and first-mag Deneb in ENE 24 degrees to Vega's lower left.
Deneb marks the head of the Northern Cross, or tail of Cygnus, the
Swan. The Cross's 2nd-mag central star, Gamma Cygni, is 6 degrees to
Deneb's south. Just south of Gamma is a bright oval patch of Milky
Way, consisting of stars in own own spiral arm! When your eyes are
fully dark-adapted, examine this cloud with binoculars. You'll see a
multitude of stars at various distances from us, ahead of us and slightly
inside our orbit of revolution around the center of our Galaxy. If you
have difficulty seeing the Milky Way, visit the website
http://www.skypub.com/lpnotes/lpnotes.html
The Last Quarter Moon, half full, rises in ENE in late evening, within 4
hours after sunset from northern U.S.
-
- One-and-a-half hours before sunup on Wednesday, the fat crescent
Moon is well up in ESE, with Aldebaran, eye of Taurus, 11 degrees to
its lower left. Venus is brilliant and low, north of due east, with faint
Mars within 10 degrees lower left. Orion, though low in the sky, is well
marked by reddish Betelgeuse in east, bluish Rigel in ESE, and his
nearly vertical 3-starred belt in between. The Gemini Twins, Castor
above Pollux, lie far to the NE, to lower left of Venus and Mars. Saturn
is high in south.
-
- From northeastern U.S. and neighboring Canada, the Moon passes
narrowly north of Aldebaran overnight, around 2 a.m. EDT Thursday --
just as they're rising in mid-Michigan. The Moon shifts eastward about
half a degree per hour. By an hour before sunup they're about 2 degrees
apart for Michigan skywatchers, closer from places farther east, and
farther from points west.
-
- Using binoculars at nighfall, look for Comet Hale-Bopp in south, 18
degrees upper right of bright Jupiter. Can you see the comet with
unaided eye? Just 1.6 degrees to its lower right is the 3.3-mag star Nu
Ophiuchi. Comet and star appear closest to each other tonight.
On Friday an hour before sunup, face east to see beautiful Venus 8
degrees to Moon's lower left. Look also for four red objects: Betelgeuse
(Orion's shoulder) 13 degrees to Venus' lower right; Mars 9 degrees to
Venus' lower left; Pollux 15 degrees to Mars' lower left; and Aldebaran
14 degrees to Moon's upper right.
-
- Tonight around nightfall Comet H-B is in south, 18 degrees upper right
of Jupiter and within 1.7 degrees N of (above) 3.3-mag Nu in
Ophiuchus. If you have a star chart with stars labeled, a line from 2.1-
mag Alpha Oph to 2.8-mag Beta Oph, 8 degrees long, extended 13
degrees lower left ends at the comet.
Watch for Perseid meteors nightly this weekend and early next week.
Their numbers increase until dawn as our side of Earth faces more
directly into the incoming meteoroid stream. For tips on observing
meteors, check the International Meteor Organization website at:
http://www.tu-chemnitz.de/~smo/imo/
As dawn (on Saturday) begins to brighten, look in east for the beautiful
gathering of Moon with Venus only 3 or 4 degrees above. Look also for
Mars and the Gemini Twins to left of Moon, and Orion to Moon's right.
Starting an hour before sunup, use binoculars to watch for the rising of
Procyon, "before the Dog", about 7 degrees N of east and 22 degrees to
Moon's lower left (or below the Moon from southern states).
-
- At nightfall, the two outermost satellites of Jupiter's Galilean satellites
are easily visible in binoculars. Callisto appears to the east (left) of
Jupiter, and Ganymede, the largest and brightest moon, appears to the
planet's west (right). For recent findings and images, visit the Project
Galileo website at:
http://www.jpl.nasa.gov/galileo/index.html
This is a great year for the Perseid meteor shower, with the Moon just a
slender morning crescent. Meteors should increase in numbers until
dawn's first light. Sunday nightfall until Monday dawn will be even
better! As dawn brightens on Sunday, look in E to ENE for the old
crescent Moon with Mars 9 degrees above, brilliant Venus to their upper
right, and the Twins to their left. Binoculars show Procyon rising 13
degrees to Moon's lower right.
-
- Tonight is the peak of the Perseid meteor shower. There's a slight
possibility of a sharp peak near nightfall in eastern North America, and a
better chance around midnight for Europe. Even if that peak doesn't
occur, the annual broad "normal" maximum will bring us its greatest
number of meteors in the dark hours just before dawn's first light on
Monday.
As dawn brightens on Monday, the slender crescent old Moon will
appear low in ENE, 25 degrees to Venus' lower left. Using binoculars,
try for Procyon rising a few degrees north of east, 11-12 degrees to
Moon's right, and still later, Sirius, the Dog Star, rising in ESE 26
degrees to Procyon's right. Seen from latitude 31 degrees north, Moon,
Sirius, and Prosyon rise together about 1 hour 25 minutes before
sunrise. From farther south, Sirius rises first, and Procyon's name,
"before the Dog", is no longer appropriate.
-
- An hour before sunup on Tuesday, find brilliant Venus in east, with
Orion's two brightest stars, Betelgeuse and Rigel, respectively 14
degrees and 33 degrees to its right. Between these stars lies Orion's 3-
star belt. Procyon, "before the Dog", has already risen; look just N of
east, 24 degrees below Venus and 26 degrees lower left of Betelgeuse.
If you're in northern U.S., wait another 15 minutes or so to catch the
rising of the "Dog Star", Sirius, in ESE. Sirius completes the Winter
Triangle with Betelgeuse and Procyon.
-
- The Moon is New on Wednesday at 3:34 a.m. EDT, so the next several
evenings are still dark enough for fine viewing of the Milky Way and
Comet Hale-Bopp. At nightfall locate bright Jupiter in S and reddish
Antares in SSW, 29 degrees to Jupiter's west. Next, locate the 3.3-mag
star Nu Ophiuchi 16 degrees to Jupiter's upper right and 27 degrees to
Antares' upper left. Comet Hale-Bopp is 2.2 degrees upper right of Nu
and shifting its position against the stars by about 1/4 degree per day.
-
- Locate bright Jupiter in S at nightfall, and look below it for eight stars of
2nd and 3rd magnitude forming the Teapot of Sagittarius. The four of
its stars to lower right of Jupiter form the Archer's bow and arrow as
well as the spout and top of the Teapot's lid; the other four stars, to
Jupiter's lower left, form the handle. The Great Sagittarius Star Cloud
(a part of the Milky Way) looks like a puff of steam just emerging from
the Teapot's spout.
-
- The center of our Milky Way Galaxy is hidden from our view by cosmic
dust clouds. It lies in a direction within 5 degrees upper right of the 3rd-
magnitude star Gamma in Sagittarius, tip of the Archer's arrow, or tip
of the Teapot's spout. Look for this star 10 degrees lower right of bright
Jupiter, in the south at nightfall.
The young Moon might be glimpsed from southern U.S. early this
evening, very low in W 20 to 30 minutes after sunset, with Mercury 9
degrees to its upper left. Use binoculars.
-
- Look very low west 30-40 minutes after sunset for the thin crescent
Moon. It's unusually low for its age, 65 to 68 hours after New from
mainland U.S. Binoculars may show Mercury within 3 or 4 degrees to
the Moon's right. The Moon sets before dark, allowing us another
superb view of the summer Milky Way. Follow its course past Jupiter
and the Teapot in the south, through the Summer Triangle overhead,
and through the "W" of Cassiopeia in the northeast. Note the "Great
Rift" of dark clouds of interstellar dust dividing the Milky Way into two
streams, from the Summer Triangle southward.
-
- About 40 minutes after sunset, find the waxing crescent Moon low in W
to WSW. As sky darkens, look for Spica 17 degrees to setting Moon's
upper left. Bright Jupiter is then in south. To find Comet Hale-Bopp,
look for the 3.3-mag star Nu Ophiuchi 16 degrees to Jupiter's upper
right. Using binoculars, look for a hazy patch of light 3 degrees upper
right of Nu. It's the comet!
-
- Look low in WSW an hour after sunset to see the crescent Moon with
Spica 5 degrees to its left. This first-magnitude star marks the spike of
wheat or ear of corn in Virgo's hand.
-
- Find Moon in SW to WSW at dusk. Watch for Spica within 9 degrees
to its lower right.
In the eastern sky before sunrise on Tuesday, note the striking
alignment of brilliant Venus with three red objects. From left to right,
they are Pollux, Mars, Venus, and Betelgeuse, shoulder of Orion, the
Hunter. Orion's belt points down to Sirius, just risen in ESE. Low in
east below Venus is Procyon, completing the Winter Triangle with
Sirius and Betelgeuse. Venus appears farthest from Sun on Tuesday, 46
degrees. A telescope shows Venus about half full.
-
- At nightfall the fat crescent Moon is low in SW. For the next few days,
binoculars show spectacular detail near the Moon's terminator (day-
night boundary). Tonight, can you see the 3rd-magnitude star Alpha
Librae about one Moon's width below the crescent's lower cusp? Comet
Hale-Bopp becomes more difficult to see in coming nights, as the Moon
brightens and moves closer to it. Tonight look 20 degrees upper right of
Jupiter, and within 4 degrees upper right of 3.3-mag Nu Ophiuchi.
-
- Examine the Moon at nightfall, noting what fraction of its disk is
illuminated. Can you determine the direction of the Sun by looking at
the Moon? Tonight the Moon is at First Quarter phase, 90 degrees or
one-quarter of a circle from the Sun. Note Antares, heart of Scorpius,
14 degrees to Moon's lower left.
-
- Today the star Regulus appears on the far side of the Sun and is hidden
in the solar glare. Six months from now, in February, the Earth will
have moved halfway around its orbit. Then the night side of Earth will
face Regulus, and the star will be visible all night. An hour after sunset,
Moon is in SW, with Antares 8 degrees below. Antares will be hidden
on the far side of the Sun at the start of December.
-
- At nightfall, the waxing gibbous Moon is in SSW. Bright Jupiter is
within 13 degrees left. Unfortunately for would-becomet-watchers,
Comet Hale-Bopp is only 12 degrees north (upper right) of the Moon
tonight.
-
- An hour after sundown face south to see bright Jupiter 5 degrees to
Moon's lower right. As night turns to dawn Sunday, Mars is within 5
degrees lower left of brilliant Venus in east. They'll remain within 5
degrees through Sept. 13, and appear within 3 degrees Sept. 2-6. Look
often and watch for changes in their positions against background stars.
-
- Although moonlight floods the evening sky, you'll still have nearly a
one-hour window of dark moonless skies Monday morning, between
moonset and first light of dawn. After Sirius rises and before Altair sets,
both the Summer Triangle in W to NW and Winter Triangle in E to ESE
are visible simultaneously, as well as three bright planets and five other
stars of first magnitude or brighter.
-
- Spica will soon disappear from the evening sky before Earth's orbital
motion makes it appear on the far side of the Sun in mid-October. Look
for the Big Dipper in NW an hour after sunset, and remember to
"Follow the arc to Arcturus (the bright star well up in west) and drive a
spike to Spica (very low in WSW)."
-
- At nightfall find first-magnitude reddish Antares in SSW, 28 degrees to
Jupiter's lower right. Note 2.4-mag Eta Ophiuchi 14 degrees uppper left
of Antares. Tonight through Sunday a line from Antares to Eta Oph,
extended 12 degrees straight past Eta (directly away from Antares),
locates Comet hale-Bopp. Beginning Saturday, moonlight won't
interfere, provided you look before moonrise. From now until Sunday
the comet will be passing 1.6 degrees above a 4.6-mag star, Mu
Ophiuchi.
-
- Across the northern U.S., from places where the air is very clear and
the east and west horizons unobstructed, it may be possible to see the
setting Sun and rising Moon simultaneously. Otherwise, wait a few
minutes and enjoy the rising Moon! Tonight's Green Corn or Grain
Moon rises about 8 degrees south of due east.
-
- The Moon rises a degree or two south of due east, half an hour after
sunset from mid-lower Michigan, and longer after sunset from more
southerly latitudes in the U.S. The rising Moon will be an impressive
sight in the deep blue twilight of the eastern horizon, opposite the Sun.
Within another hour, Saturn appears about 10 degrees to Moon's lower
left.
-
- Tonight the Moon rises about 5 degrees N of due east, within 1-1/4
hours after sunset as seen from northern U.S. Satuirn appears 4 or 5
degrees to Moon's right. By an hour before sunup Saturday, Moon is
well up in SW, with Saturn 8 degrees to its lower right.
-
- Beginning tonight, if you look before moonrise, you'll have dark skies
for viewing the Milky Way and Comet Hale-Bopp. The dark window is
brief tonight, with Moon rising only 1-3/4 hours after sundown for
Michigan skywatchers, and later for viewers farther south. At nightfall,
locate Jupiter in S and Antares in SSW, 28 degrees lower right of
Jupiter. Look for 2.4-mag Eta Ophiuch 14 degrees upper left of
Antares, and Comet H-B another 11 degrees upper left of Eta. All three
bodies appear in a straight line. A 4.6-mag star, Mu Ophiuchi, lies 1.6
degrees below the comet.
-
- In the eastern morning sky for over three hours before sunrise, Venus
and Mars are just 3 degrees apart all this week; they appear closest at
midweek, as Venus passes within 2.9 degrees south of Mars.
-
- Jupiter, in the south as darkness falls, ends retrograde this week. Note
the 3rd-magnitude star Lambda Sagittarii, northern star of the Archer's
bow and top of the Teapot, just 2-1/2 degrees lower right of Jupiter. A
telescope shows a ball of stars 0.7 degree from Jupiter. In coming
weeks, even as Jupiter and the Teapot drift toward the southwest
horizon, watch the planet slowly move eastward against the stars,
increasing its distance from Lambda.
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