To the reader:
The Skywatcher's Diary for October 2002 has been prepared by
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 October issue, please send a long,
self-addressed stamped envelope to:
October 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
http://www.pa.msu.edu/abrams/SkyWatchersDiary/Archives.html
ftp://www.pa.msu.edu/pub/swd/
Skywatcher's Diary: October 2002
The waning crescent Moon can be found more than halfway up in the east-
southeast at dawn this morning. The two bright stars above Luna belong to
Gemini, the Twins. Pollux is 7 degrees (14 moon diameters) up and Castor
another 5 degrees higher. Tomorrow morning the Moon slides down to join
Jupiter in a pose worthy of a photograph. Jupiter's Ð2 magnitude dot punctuates
the Moon's nearly horizontal crescent. Four degrees separate the sky mates. You
will be glad you took a moment from your early morning schedule to sneak a
peek.
The thin crescent Moon sits among the stars of Leo tomorrow morning. Regulus,
the brightest star in the constellation, hangs 5 degrees (10 moon diameters) to
the lower right an hour before sunup. Regulus marks the heart of the mighty lion.
To the moon's upper left are several fainter stars forming a partial circle that
represents Leo's head. Old timers know this region as "The Sickle." If you
carefully examine the area around the Moon before 5:15 a.m., you should notice a
4th magnitude star, Eta, very close to the moon's lower left. Shortly thereafter the
Moon passes in front of the star, covering it for about an hour. The event is best
observed with a telescope.
Over the next two mornings the Moon points the way to Mars and Mercury. Both
planets are a relatively faint 2nd magnitude. Mars remains dim all month while
Mercury brightens rapidly to Ð1 by mid month. We are catching Mercury at the
beginning of its best morning appearance for the year. Tomorrow morning look
for Mars 10 degrees (a fist width) directly below the Moon, due east. Optimum
time to observe is 45 minutes before sunrise. Mercury sits 6 degrees below Mars,
only 2 degrees above the horizon at that time. The following morning the Moon
perches 6 degrees to the lower left of Mars and 5 degrees upper right of Mercury.
Although both planets display similar luminosities, you'll have more difficulty
locating Mercury. Our atmosphere is less transparent and twilight is brighter at
the lower altitude. Use binoculars.
Venus sets 45 minutes after sunset so it is becoming difficult to spot in twilight,
low on the horizon. There is no need to wait until twilight, however. In fact, if you
wish to glimpse its phase through a telescope or powerful binoculars, observing
after sunset is detrimental. Daylight is better because Venus doesn't glare as
much. Try observing half an hour before sunset. At that time Venus sits 10
degrees up due southwest. Use binoculars to scan the area if you don't pick out
Venus with naked eye. Once located with optical aid, try to find the planet again
using just your eyes. It is easier than most people think. The trick is in knowing
precisely where to look. Will you qualify for the small but distinguished group of
humans who have observed Venus in the daytime?
Some evening this month when the Moon's not out, look for planet number seven,
better known as Uranus. The 6th-magnitude object is just distinguishable to
average eyesight under dark conditions, although binoculars are best. It currently
resides among the faint stars of Capricornus. Uranus stays within 3 degrees of
that constellation's brightest star, 3rd-magnitude Delta, and within a degree of 5th-
magnitude Mu. The planet is due south and highest tonight around 10:30 p.m.
EDT. That time shifts about 1 hour 45 minutes earlier by the end of the month,
ignoring the change to standard time. To be successful you need to recognize the
shape of Capricornus and familiarize yourself with the region around Uranus.
Here's a website to start you out:
http://skyandtelescope.com/observing/objects/planets/article_412_1.asp
New Moon occurs this morning at 7:18 a.m. EDT. The Moon and sun are then
roughly aligned in space. The gravity of each body pulls on Earth from the same
direction. Tides created by the sun and Moon therefore reinforce each other,
producing the so-called "spring tides," the highest of the month. Lunar perigee
also occurs today, less than two hours after New Moon. It's the second nearest
approach the Moon makes to Earth this year. Closer Moon means increased
gravitational pull, so the tides are further enhanced. Bottom line: the second
highest tides of the year will occur today. Study question: Why are the tides that
occur at Full Moon also known as spring tides?
If you want to catch the young Moon this evening, you'll need to be quick. It sets an
hour after the sun. Thirty minutes after sundown look for it 4 degrees (8 moon
diameters) above the west-southwest horizon. Venus is 13 degrees to the Moon's
left but on the horizon at that time. If you are serious about spotting Venus, start
earlier, at sunset perhaps. Locate Venus first, then see how soon after sunset
you can pick up the Moon, first with binoculars and then unaided eye.
The thin crescent Moon is a captivating sight. Mix in a little sunset color and you
have a scene that even the cynical among us will pause to admire. Be sure to
note the "earthshine," the soft gray glow that illuminates the Moon's left side. Luna
sets 1 1/2 hours after the sun, just as astronomical twilight ends. Earlier, soon
after sunset, notice Venus 10 degrees (a fist) directly below the Moon. Tomorrow
night Luna approaches the star Antares, heart of Scorpius. Look for it 6 degrees
(12 moon diameters) to the Moon's left, and slightly lower.
Inspect the crescent Moon with binoculars this evening. Although it may appear
featureless when you first glance, examine more thoroughly. Can you detect the
large darkened circular feature a quarter of the way from the top of the crescent?
Its name is Mare Crisium, the Sea of Crisis. The site marks an ancient 300-mile
wide crater. Its gray cast comes from ancient lava that long ago solidified. Notice,
also, how rough the crescent's left edge appears. Higher magnifying power
reveals the cause: numerous smaller craters. Continue to carefully observe the
changes in the Moon over the next several nights.
Tonight the Moon slides 10 degrees (a fist) to the upper left of Antares, brightest
star in Scorpius. It also sits near the direction toward the center of our home
galaxy, the Milky Way. That point is about 8 degrees to the Moon's left this evening,
and 6 degrees to its lower right tomorrow night. Although near Antares tonight, the
Moon is actually among the stars of Ophiuchus (off-ee-YOU-kuss) the Serpent
Charmer. This group is sometimes referred to as the 13th zodiac constellation,
since the plane of the solar system passes through it, just as it does the 12
classical zodiac constellations.
The Moon, just a day away from First Quarter, rests over the top of the "teapot's
spout," a portion of the constellation Sagittarius. Venus now sets less than 30
minutes after the sun. Continue to hunt down the planet for as many nights as you
can. Venus' orbit carries it ever closer to Earth. Even though the planet's crescent
shape, as seen in a telescope, grows thinner with each passing night, its
apparent size enlarges. At some point soon you may be able to distinguish the
planet's phase with only binoculars! Shortly thereafter Venus disappears from the
evening sky.
Mercury has been cozying up to Mars, in the morning sky. Two days ago they were
just less than 3 degrees apart. This morning slightly over 3 degrees separates
the two bodies. Tomorrow Mercury reaches the bend in its orbit (greatest
elongation) and then slowly settles back toward the horizon through the rest of the
month. While Mars remains relatively faint at magnitude 2, Mercury has
brightened to almost Ð1. Look for the duo in the east an hour before sunrise.
You'll likely spot Mercury first, 6 degrees (half a fist) above the horizon. Mars is to
its upper right. The Red Planet's ruddy hue should aid identification.
The Moon passes First Quarter phase this morning at 1:33 a.m. EDT. By the time
you spot it this evening there should be no question that the sphere is more than
half illuminated. The Moon is on the border between the constellations of
Sagittarius and Capricornus, in a particularly faint part of the zodiac. Neptune lies
10 degrees (a fist) to Luna's upper left, and Uranus is another 17 degrees farther
left. Both planets currently reside in Capricornus. To locate them you'll need a
detailed finder chart. Don't bother while the Moon is in their vicinity.
Tonight the gibbous Moon sits squarely within Capricornus. Tomorrow night it
approaches the constellation's eastern boarder. Then, try to find a 3rd-magnitude
star 3 degrees (6 moon diameters) to the Moon's upper right. The star, brightest
in Capricornus, is Delta. Learning to locate the star in a dark sky is useful for
finding Uranus, since the planet currently resides 2 degrees to its upper left. Look
for the star on successive nights as the Moon moves out of the way.
The two brightest objects in the morning sky now rise together 6 hours ahead of
the sun, or around 2 a.m. EDT. One is a planet, the other a star. Can you guessed
their identities? They are the largest planet and the brightest nighttime star:
Jupiter and Sirius. Stars rise 4 minutes earlier a day, or about 2 hours sooner
each month. So by mid November look for Sirius to come up around midnight.
Jupiter moves relative to the stars, but slowly. By mid November it rises only about
30 minutes later than Sirius.
An hour after sunset the gibbous Moon stands 21 degrees (2 fists) above the
southeast horizon. Fifteen degrees below and slightly right of the Moon shines 1st-
magnitude Fomalhaut (FOE-mall-ought), in Piscis Austrinus (PIE-sis aw-STREE-
nus), the Southern Fish. The name derives from Arabic, meaning "mouth of the
whale or fish." Because the star sits low, its light is easily diminished by
atmospheric haze near the horizon. The star is intrinsically similar to Vega, the
brightest star in the Summer Triangle. Both stars are white with surface
temperatures near 16,000 degrees Fahrenheit. They are also roughly the same
distance, 25 light years away. Four hours after sunset Fomalhaut stands highest,
18 degrees above due south.
The gibbous Moon rises an hour before sunset just to the south of due east. It
sits among the stars of Aquarius, but finding any recognizable stars of that
constellation would be difficult tonight. Even after the end of twilight, Luna's
brilliance will mask the faint stars of the Water Carrier. The two brightest stars in
Aquarius (Alpha and Beta) are only 3rd magnitude. They both sit to the upper right
of the Moon this evening, roughly 25 degrees (2 1/2 fists) away and 10 degrees
apart. Their proper names are Sadalmelik and Sadalsuud, both of Arabic origin
and meant to signify lucky stars.
Saturn rises in the northeastern sky 3 1/2 hours after sunset, or around 10:15
p.m. EDT. Before the ringed beauty comes up, two bright stars and a star cluster
make their appearances in the same general direction. Capella, a zero-
magnitude star low in the north-northeast, is first to be noticed as twilight
descends. The Pleiades star cluster, commonly known as the Seven Sisters is
next to break the horizon (in the northeast), 1 hour after sunset. Two and a half
hours after sundown look for Aldebaran to rise in the east-northeast.
If you previously observed Mars and Mercury when they were 3 degrees apart, you
should take another look. The two planets are now separated by 7 1/2 degrees.
An hour before sunrise (around 7 a.m.) is a good time to view. Mercury, -1
magnitude, then sits 4 degrees above the eastern horizon, 7 degrees to the south
of due east. Second-magnitude Mars is to its upper right. Mercury drops rapidly;
each morning it sits lower and is gone by the end of the month.
Tonight the Moon rises within minutes of sunset, slightly north of due east.
Technically the Moon is Full tomorrow morning at 3:20 a.m. EDT, so tonight's
rising Moon might more aptly bear the designation of Hunter's Moon than
tomorrow's. If you have the opportunity to see the Moon once or twice in the
middle of the night, notice how high it travels. The Full Moon's path tonight is
similar to the sun's daytime path in May. When the Moon is highest, about 7 hours
after sunset (2 a.m.), it stands 60 degrees up in the south.
The Orionid meteor shower, so named because the meteors seem to radiate
from Orion, is a minor shower that seems to draw publicity. Perhaps it's due to
the shower's association with one of the best-known constellations. Under ideal
conditions the shower produces 20 meteors per hour, or an average of one every
3 minutes. The situation is far from ideal this year, however. Glare from the Full
Moon may well diminish the number you can detect to 5 per hour. If you are
determined, look tonight after midnight up until the start of dawn tomorrow
morning. Or you may wish to save yourself for the potential meteor storm coming
November 19. Stay tuned.
For newcomers, here's a quick survey of the 6 stars that are 1stmagnitude or
brighter and currently above the horizon near the end of evening twilight, about 1
1/2 hours after sunset. High in the southwest find the three bright stars that form a
large triangle. The brightest is Vega, toward the northwest. Deneb is almost
overhead, and Altair is more than half way up in the south-southwest. The other 3
bright stars are within 10 degrees (a fist width at arm's length) of the horizon.
Capella is rising in the north-northwest. Look for Fomalhaut in the south-
southeast. Arcturus is setting in the west-northwest.
For a star map to assist in locating these stars and other celestial objects, send a
stamped, self-addressed envelope to Sky Calendar, Abrams Planetarium,
Michigan State University, East Lansing, MI 48824.
The Moon rises near the end of twilight tonight, so we are heading into a period of
moonless evening skies. The band of Milky Way is ideally situated for viewing, as
it rises out of the northeast, passes directly overhead, and falls toward the
southwest horizon. Coincidentally, the direction to the center of our galaxy is
setting near the southwestern horizon. With correct timing you can look straight up
and see the direction the Earth and solar system are headed in our journey
around the hub of the Milky Way, gaze to the southwest in the direction of the core
we're traveling around, then turn 180 degrees to face northeast and stare away
from the center into distant space.
This morning before sunrise the waning gibbous Moon sits between Aldebaran,
the bright star in Taurus, and the Pleiades star cluster. Aldebaran is 7 degrees
(14 moon diameters) to the upper left of Luna while the Pleiades are found 7
degrees to the lower right. Tomorrow morning the Moon jumps to 10 degrees
above Aldebaran and 12 degrees to the lower right of Saturn. The name
Aldebaran is Arabic and translates as "The Follower," referring to the Pleiades.
Aldebaran trails the star cluster across the sky.
Tomorrow morning the Moon rendezvous with Saturn. The planet is 3 degrees (6
moon diameters) to Luna's lower left. Twenty to 30 degrees in the same direction
you will notice Orion, and 20 degrees in the opposite direction sits Capella,
brightest star in Auriga, the Chariot Driver. The Moon is near the center of the
spectacular winter grouping of bright stars. Also in the vicinity are the Gemini
Twins, Canis Minor (Small Dog), and Canis Major (Big Dog). The following
morning (Sunday) look for the Moon 14 degrees to the upper left of Saturn and 10
degrees to the lower right of the twin bright stars of Gemini.
Tomorrow morning at 2 a.m. most of the United States reverts to standard time.
Remember to set your clocks back an hour before retiring. Lest you think this time
shifting is strictly an American idiosyncrasy, more than half of the world joins in.
The dates they observe the time switch may be different, but North America,
Europe, and Russia all participate, as do New Zealand, Egypt, Brazil, Chile, parts
of the Middle East and Australia. To see a complete list of the countries and the
dates they make the change visit http://www.worldtimezone.com/daylight.htm.
It's almost the last chance to see Mercury during its morning apparition. Look
tomorrow morning 40 minutes before sunrise (about 6:30 a.m. EST). Mercury sits
only 2 degrees above the eastern horizon, slightly south of due east. Binoculars
may be necessary to locate it. Fainter Spica is 4 degrees to the planet's lower
right. Mars is 16 degrees to the upper right. Jupiter is located another 50 degrees
in the same direction, then the Moon, 21 degrees from Jupiter, and lastly, Saturn
27 degrees past the Moon. The entire span of planets, Mercury to Saturn,
stretches 115 degrees. All of the bodies lie in the solar system plane, so they
provide a convenient way to trace the zodiac.
If you caught a glimpse of the Moon this morning before sunrise you might have
noticed two stars in line with it. They are the principal stars of Gemini. Pollux sits 4
degrees (8 moon diameters) to the Moon's upper right and Castor is another 5
degrees beyond Pollux. Last Quarter occurs tonight (technically tomorrow
morning) at 12:28 a.m. EST. At that moment Luna hangs low in the east-
northeast, having risen only an hour and 20 minutes earlier. Jupiter appears just
above the horizon, 10 degrees directly below the Moon. The Moon makes a
particularly nice target for telescope and binoculars over the next several
mornings. The bright crater near center tonight is Copernicus, 60 miles wide and
almost 13,000 feet deep.
The Moon and Jupiter rise in concert tonight soon after midnight. Look for them in
the east-northeast. The two objects are then 6 degrees (12 moon diameters)
apart. By dawn the Moon slides 2 degrees farther away. In a dark sky you may
notice Regulus, brightest star in Leo, the Lion, 8 degrees below the Moon. The
next morning (Thursday) the Moon hopscotches over Regulus. It is found 8
degrees to the star's lower left, in the belly of the lion. Leo must have needed a
midnight snack.
Saturn rises 3 hours after sunset. With the sun disappearing so early these
evenings, the planet is high enough for serious telescopic observing before
midnight. Adding to the show, the planet's rings are near their maximum tilt, as
seen from Earth, so they present almost the broadest face possible -- an ideal
time to examine the subtle features of the rings. The extreme ring tilt is also the
primarily reason that in December Saturn reaches its greatest brilliancy in more
than a decade.
Tomorrow morning the Moon appears 19 degrees (2 fists) above Mars. The Red
Planet may be hard to distinguish since it's only 2nd magnitude. Nevertheless it is
the brightest object in the vicinity. An hour before sunrise Mars hangs 15 degrees
up in the east-southeast. The 1st-magnitude star Spica is 14 degrees below Mars
but rises only an hour and 15 minutes before the sun. Earlier in the evening,
before moonrise, you may notice ethereal apparitions. Little is known about them
except that they materialize each year at this time. Happy Halloween.
Please send any comments, suggestions, or questions to
Thomas G. Ferguson:
fergus52@msu.edu
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