Abrams Planetarium
SKYWATCHER'S DIARY: September 1997
To the reader
The Skywatcher's Diary for September 1997 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 issue of Sky Calendar from a previous month is available
over the Internet. It can be viewed via a World-Wide Web browser such as
Netscape or Internet Explorer, directly at URL:
http://www.pa.msu.edu/abrams/apr97skycal.html
If you would like a printed sample of the September issue, send a long,
self- addressed stamped envelope to:
September 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 Internet
Explorer, 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/
September Planetary Highlights:
Evening Planets: Venus gleams low in WSW to SW at dusk. Its setting
place continues to shift southward until Nov. 6. Venus appears as brightest
"star" in the night sky, and starting this month until early January
it sets after the sky has completely darkened. Spica is within the
same binocular field as Venus early in month. Mars is upper left
of Venus, by 24 degrees on September 1, closing to 10 degrees by September
30. Antares is upper left of Mars, by 28 degrees to 9 degrees. Late
in month, watch the changing configuration of Venus, Mars, and Antares,
as both planets approach the star from the lower right. They'll form a very
compact gathering in October. Bright Jupiter is in SE to SSE at dusk,
and climbs to its high point in south an hour or two after nightfall. Once
Venus has set, Jupiter is brightest "star" in sky until it finally
sets, in the post-midnight darkness hours.
Evening until dawn: Saturn rises just N of E about 1-3/4 hours
after sunset Sept. 1, to half an hour after sunset on Sept. 30, and is in
WSW to W at dawn. Saturn reaches its high point in south four hours after
Jupiter does, but 23 degrees higher. Saturn's rings are now nearky 11 degrees
from edge-on; they were edgewise and invisible just two years ago. Mercury
can be spotted very low in E at dawn, starting around Sept. 9.
On Sept. 4 and 5 at dusk a thin crescent Moon forms gatherings
with Venus and Spica which can be enjoyed with binoculars. As the Moon waxes
from crescent to full Sept. 4-16 and moves eastward from Venus, it guides
skywatchers to two additional planets and a bright star: Mars Sept. 6 and
7, Antares on Sept. 8 and 9, and Jupiter on Sept. 13. On the night of Sept.
17-18, Saturn rises close on the heels of the Moon just past Full, then
is covered by the Moon from some locations (see Sept. 17). In the predawn
hours of Sept. 21 and 22, the Moon is near Aldebaran. One to three hours
before sunup on Sept. 28, Regulus is closely upper left of a beautiful waning
crescent Moon. Finally, on Sept. 30, low in the east 45 minutes before sunup
in twilight, a very thin Moon is close to Mercury.
Skywatcher's Diary: September 1997
Monday, September 1
- New Moon occurs today, 7:52 p.m. EDT. In evening sky in next two weeks,
Moon passes three bright planets and two bright stars. Look nightly at
dusk, starting Wednesday. A partial solar eclipse can be viewed from Australia
and New Zealand, where the local date is Sept. 2.
Tuesday, September 2
- Observers in Hawaii have a chance to spot a very slender crescent Moon,
29 hours after New. Using binoculars 20 minutes after sunset, look due
west, 3 to 4 degrees up, 26 degrees lower right of brilliant Venus. Viewers
in the contiguous 48 states must wait until Wednesday for their first easy
view of the 2-day-old crescent.
The Mir Russian Space Station may soon be making morning passes
over North America. For predictions for various cities, visit the SatPasses
Website at: http://ssl.berkeley.edu/isi_www/satpasses.html
Wednesday, September 3
- About 15 to 30 minutes after sunset, look for Venus in WSW, and a slender
crescent Moon very low, just S of due west and 17 degrees lower right of
Venus. As sky darkens, the first-magnitude star Spica becomes visible 4
degrees to Venus' left. (Binoculars give a fine view of Venus and Spica
within the same field.) Look also for Mars 23 degrees to Venus' upper left.
Thursday, September 4
- Tonight and Friday, from 45 minutes to an hour after sunset, look low
in WSW for a gathering of the crescent Moon with Venus and the star Spica.
Tonight Venus and Spica are 2.7 degrees apart, to the Moon's left. Mars
is 22 degrees to Venus' upper left, and Antares, the first- magnitude star
marking the heart of Scorpius, is 26 degrees upper left of Mars. Within
next five nights, watch the Moon overtake Venus, Spica, Mars, and Antares.
Friday, September 5
- A beautiful sight at dusk: A 4-day-old crescent Moon low in WSW, with
Venus and Spica 2 degrees apart a few degrees below them. Note Mars and
Antares about 18 degrees and 43 degrees to Moon's upper left.
Saturday, September 6
- This evening Venus and Spica appear closest, with the star just 1.7
degrees lower left of the brilliant planet. Look very low WSW at dusk,
about 15 degrees to Moon's lower right. Binoculars give the best view of
the twilight pairing. Mars is 7 degrees to Moon's lower left. Venus and
Mars are 21 degrees apart, and seven more weeks will pass before Venus
finally catches Mars.
Sunday, September 7
- Tonight at dusk locate the fat crescent Moon in SW with Mars about
7 degrees to its lower right. The first magnitude reddish star Antares,
whose name means "Rival of Mars," is 24 degrees to Mars' upper
left. In five weeks Mars will pass Antares. Spica is still visible in twilight
2.2 degrees lower right of Venus in WSW. For how many more evenings can
you track Spica? It gets lower each night (because of Earth's revolution
around the Sun), and will be on the far side of the Sun in mid-October.
Monday, September 8
- The red star Antares, heart of Scorpius, is in SSW at dusk, about 10
degrees to Moon's lower left. As sky darkens, look for three stars in the
Scorpion's head, in a slightly curved nearly vertical line below the Moon.
Tuesday, September 9
- Face the setting Sun just north of due west this evening, then look
90 degrees to your left for the Moon, just west of due south. Although
the Moon's right half is illuminated, the Moon's phase is called First
Quarter because the Moon has moved a quarter of the way around the sky
from the Sun's position. As the sky darkens, look for Antares 11 degrees
to Moon's lower right.
On Wednesday and Thursday, first-magnitude Mercury is 3.3 degrees below
Regulus in E at dawn. Overlooked in most almanacs, this event is a "quasi-conjunction,"
i.e. Mercury approaches Regulus without going past it. For about 15 minutes,
starting an hour before sunrise, binoculars show pair in same field. Mercury
climbs higher in next week and brightens, fast becoming prominent to unaided
eye.
Wednesday, September 10
- In WSW at dusk, use binoculars to see Spica 5 degrees to Venus' lower
right. Mars is 19 degrees to Venus' upper left. To lower left of Moon at
nightfall, look for the eight stars of 2nd and 3rd magnitude forming the
Teapot in the constellation Sagittarius, the Archer.
Thursday, September 11
- In the south an hour after sunset, look for a 2nd-magnitude star 7
degrees below the Moon. It is Nunki, or Sigma Sagittarii, brightest star
in handle of the Teapot. Venus will pass very close to this star on Nov.
17. Keep watching!
Friday, September 12
- Bright Jupiter is in SE at dusk. An hour after sunset, look 16 degrees
lower left of the waxing gibbous Moon.
Saturday, September 13
- Moon and bright Jupiter keep close company for most of the night. In
the evening they're 3 degrees apart in SE with Jupiter below the Moon.
Four hours before sunrise on Sunday, they're low in WSW with Jupiter 4
degrees to Moon's lower left.
Sunday, September 14
- At dusk, Jupiter shines in SE 15 degrees to Moon's upper right.
Monday, September 15
- Can you see four naked-eye planets simultaneously? It's getting easier
day by day. Shortly before Venus sets in WSW, watch for Saturn just risen
a few degrees north of due east. At the same time look for bright Jupiter
well up in SSE, and faint Mars low in SW, 17 degrees to Venus' upper left.
Mercury, the other bright planet, can be seen an hour before sunrise
very low, just north of east. On Wednesday morning Mercury is 6 degrees
below Regulus and is at its farthest angular distance from the Sun (18
degrees) during its current apparition. This is the best week of this year
to see Mercury as a morning "star".
Tuesday, September 16
- A few hours after emerging from a total lunar eclipse visible in the
Eastern hemisphere, observers in North America can watch a Harvest Moon
rise within a few minutes after sunset. Does the Moon look larger than
usual? A rising Moon always seems large, even when it's farthest from Earth,
but tonight we are seeing the closest Full Moon of the year, so its angular
size actually is large!
The special characteristic of the annual Harvest Moon is that on the
nights after Full, the Moon rises farther north each night, producing a
noticeably shorter than the average 50-minute daily delay in moonrise times.
So even a few nights after Full, the Moon rises before twilight has faded
in the west, thus providing continuous light for late-working farmers bringing
in the crops. In this year's Harvest Moon these effects are somewhat muted,
because the Full Moon is near its closest to Earth and moves more swiftly
in its orbit, and because this month the Moon's orbit is more steeply inclined
to the sunset horizon than it is in most Septembers. Both effects cause
the Moon to "bury itself" farther below the eastern horizon on
each successive night than it otherwise would, diminishing the effect of
the Harvest Moon. (As an example, in East Lansing, Wednesday' moonrise
will occur 37 minutes later than tonight's. In some years from the same
location, the delay can be less than 25 minutes.)
On Tuesday, look again about 1-3/4 hours after sunset, and locate Saturn
just risen in east, 20 degrees to Moon's lower left. Check Wednesday's
entry for information on an unusual event which will be widely seen in
parts of Hawaii and North America that night.
Wednesday, September 17
- About 1-3/4 hours after sunset, locate Saturn very low in east, about
5 degrees to Moon's lower left, depending on your location. Late this evening
from the Island of Hawaii, or Thursday morning from many places in western
and central U.S., the Moon occults or covers Saturn. The event is
visible S of a line crossing through the Hawaiian Islands, central California,
Nevada, Utah, Wyoming, Nebraska, S. Dakota, Minnesota, Wisconsin, and northern
lower Michigan. A telescope will be required to see Saturn very near the
bright Moon. Observers south of the line will see Saturn get totally covered;
those north of the line will see a narrow miss. Here are times of Saturn's
disappearance and reappearance for selected cities: Hilo HI 11:03-11:22
p.m. HST. Los Angeles 3:12-4:02 a.m. PDT; Denver 4:40-5:14 a.m. MDT; Austin
5:33-6:40 a.m. CDT; New Orleans 5:42-6:47 a.m. CDT; Kansas City 5:45-6:40
a.m. CDT; Chicago 5:56-6:29 a.m. CDT; Atlanta 6:49-7:47 a.m. EDT; East
Lansing 7:00-7:28 a.m. EDT. Twilight or daylight will interfere with viewing
from eastern U.S. The reappearance is around sunrise if you're near a line
from Michigan to Mississippi. The disappearance is around sunrise near
a line from Toronto to N. Carolina. The farther west you are of these lines,
the darker the sky will be. For more information, see September 1997 Sky
& Telescope, pp. 94-96, and the World Wide Web at: http://www.sky.net/~robinson/0918satp.htm
Thursday, September 18
- Moon rises 10 degrees N of east about 1 hour 25 minutes after sunset
as seen from the latitude of lower Michigan, and a little later for observers
farther south. Note Saturn about 10 degrees upper right of rising Moon.
Friday, September 19
- Dark skies and good Milky Way viewing return tonight, at least in the
brief interval between the end of evening twilight and moonrise. Seen from
the latitude of lower Michigan, the Moon rises just over two hours after
sunset.
If you're in our area this weekend or next, you're welcome to join us
at Abrams Planetarium for Autumn Skies, a preview of this season's
beautiful arrangements of bright evening planets and stars. Showtimes are
Fridays and Saturdays at 8:00 p.m., and Sundays at 4:00 p.m., September
19-21 and 26-28. Also opening this weekend is our new family show, WSKY,
Radio Station of the Stars. It is presented Sundays at 2:30 p.m. For
further information and admission prices, please call (517) 355-4672.
Saturday, September 20
- An hour after sunset, find Venus very low in WSW, with Mars and Antares
14 and 30 degrees to its upper left. The waning gibbous Moon, three-quarters
full, rises in ENE within three hours after sunset. Note the Pleiades star
cluster 10 degrees to Moon's upper left. Another hour later, watch for
Aldebaran, eye of Taurus, rising 11 degrees to Moon's lower left. By an
hour before sunup on Sunday, they'll be 8 degrees apart, high in SSW.
Sunday, September 21
- Four hours after sunset, Moon has just risen in ENE, with Aldebaran
some 2 or 3 degrees to its upper right. By an hour before sunrise on Monday,
Moon is high in S, with Aldebaran about 6 degrees to its right.
Monday, September 22
- Autumn begins today at 7:56 p.m. EDT, as the Sun stands directly over
Earth's equator. On Tuesday an hour before sunrise, the Moon is approaching
the south, with Betelgeuse, Orion's shoulder, 10 degrees below. Saturn
is in WSW, and Mercury is very low, 7 degrees N of E and 15 degrees below
Regulus. At sunrise, the Moon is high in south. Note its shape is half
full. Since its is 90 degrees or one-quarter circle west of the Sun, it
is at Last Quarter phase. The Moon's position among the stars Tuesday morning
is roughly the same as the Sun's position three months or a quarter of
a year ago.
Tuesday, September 23
- An hour before sunup on Wednesday, the fat crescent Moon is in SE.
The Gemini twins, Castor above Pollux, are about 17 degrees to Moon's left,
and Procyon, the Little Dog Star, is 17 degrees below the Moon.
Wednesday, September 24
- On Thursday an hour before sunup, the Moon is between Pollux and Procyon,
11 degrees from each. Procyon is the brighter, to Moon's lower right. Castor
is 4-1/2 degrees upper left of Pollux.
Thursday, September 25
- An hour after sunset, face SW to see brilliant Venus with Mars and
Antares to its upper left. Tonight through this weekend Mars is located
midway between the other two. Tonight the spacing between bodies is 12
degrees, and getting smaller each night.
Friday, September 26
- On Saturday an hour before sunrise, the waning crescent Moon is in
E to ESE, with the star Regulus 11 degrees lower left.
Final weekend of Autumn Skies at Abrams Planetarium: Tonight
and Saturday at 8 p.m., and Sunday at 4 p.m. For more, please see Sept.
19, or call (517) 355-4672.
Saturday, September 27
- An hour before sunrise on Sunday, the crescent Moon is in the east,
with earthshine illuminating its dark side, and Regulus, heart of
Leo, 2 to 3 degrees upper left. In the next few minutes, watch for the
planet Mercury rising about 5 degrees north of due east.
Sunday, September 28
- An hour before sunrise on Monday, the slender crescent Moon is low
in east, with Regulus 13 degrees above. Within 15 minutes if the sky is
very clear, you might see Mercury rising about 12 degrees to Moon's lower
left.
Family show, WSKY, Radio Station of the Stars, continues Sundays
at 2:30 p.m. at Abrams Planetarium.
Autumn Skies, final showing at 4:00 p.m. today at Abrams Planetarium.
Monday, September 29
- Hale-Bopp Update, six months after perihelion: Comet Hale-Bopp
is now 2.89 astronomical units (nearly 270 million miles) from the Sun,
or over three times more distant from the Sun than it was at its closest
just half a year ago, on March 31. If you're in southern U.S., south of
latitude 34 degrees (latitude of Atlanta and Los Angeles), try for the
comet, now faded to 5th or 6th magnitude. From a clear dark site 1-1/2
hours before sunrise, or just before dawn's first light, locate Sirius,
the brightest star, in SSE, then find 2nd-magnitude Eta in Canis Major
15 degrees below Sirius. As a check, Eta is the lower left member of a
prominent compact triangle of three 2nd-magnitude stars forming the hindquarters
of Canis Major. Using binoculars, scan just above the horizon 13 degrees
below Eta for another 2nd-mag. star, Zeta Puppis. Keep in mind that a 2nd-mag.
star near the horizon appears fainter than one higher up. Can you see a
small hazy spot of light 3 degrees upper left of Zeta? It's Comet Hale-Bopp!
On Oct. 6 it will pass 1.2 degrees lower left of Zeta.
Wherever you are in the U.S. on Tuesday morning, about 45 minutes before
sunrise aim your binoculars due east, and with an unobstructed view you
may see a very delicate hairline crescent Moon with Mercury in the same
field. From mid-Michigan, the Moon is 30 hours before New, and Mercury
is within 3 degrees to its lower left.
Tuesday, September 30
- Face SW an hour after sunset. Find brilliant Venus with Mars 10 degrees
to its upper left; Antares in turn is 9 degrees left of Mars. These three
bodies will be fascinating to watch in October, as all will fit within
a single field of 7-power binoculars for about 10 days.
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