To the reader:
The Skywatcher's Diary for November 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 November issue, please send a long,
self-addressed stamped envelope to:
November 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: November 2002
This morning an hour before sunrise the waning crescent Moon sits 15 moon
diameters to the lower right of Denebola, a 2nd-magnitude star that marks the tail
of Leo, the Lion. Tomorrow morning the crescent slides lower, into Virgo. The
planet Mars, still only 2nd magnitude, is then poised 6 degrees (12 moon
diameters) below the Moon, and slightly right. At that point the Moon is just shy of
2 1/2 days before New. The nearly horizontal crescent will appear to hold up the
dusky earthshine portion of the Moon, an effect that is dubbed the "old moon in
the young moon's arms."
Tomorrow morning will be your last opportunity to view the Moon before New
phase. An hour before sunrise the slender crescent sits 7 degrees (almost a fist
width) off the horizon and 14 degrees to the right (south) of due east. The 1st-
magnitude star Spica can be spotted 6 degrees to the lower right of Luna. Spica
is the brightest star in the otherwise faint zodiac constellation of Virgo. The
constellation's other significant members are merely 3rd and 4th magnitude. Virgo
marks the part of the zodiac that the sun inhabits from mid September through
October.
Today marks the first day of summer for the northern hemisphere. No, that's not a
mistake, only an omission of the planet name: Mars. The planet's north pole is
now tipped its maximum extend toward the sun, about 25 degrees. On Earth our
23.5-degree axis inclination is responsible for the climate differences we call
seasons. For Martian seasons, the planet's varying distance from the sun plays a
significant secondary role to its axis tilt.
The South Taurids, a minor meteor shower, peaks today. If you notice any
meteors while out observing, see if the streaks trace back toward the
constellation Taurus.
New Moon occurs this afternoon at 3:34 p.m. EST. Ramadan, the Muslim month
of fasting, begins either Wednesday or Thursday. The uncertainty relates to
interpretation and geographical differences. Ramadan commences the day after
the evening of the first sighting of the young moon after New. Some Muslim
groups determine the date by astronomical calculations. Others depend on sky
observation. For them only when the crescent is actually seen can the month
begin. Clouds can also delay the holy observance. Most Muslims in the Americas
should be able to spot the crescent tomorrow night, although the farther north, the
harder the task becomes. The northern tier of states and points beyond are
questionable. For most of the rest of the Islamic world, Ramadan should begin a
day later.
For the faithful seeking the start of Ramadan and those curious non-Muslims, the
young crescent Moon sits 3 degrees (6 moon diameters) above the west-
southwestern horizon (azimuth 240 degrees) 20 minutes after sunset. You'll need
a flat western horizon and crystal clear skies. Begin the search a few minutes
after sunset and keep trying until the Moon sets, about 45 minutes after the sun.
Binoculars may be needed to initially locate the crescent. Tomorrow night the
Moon will be much easier. It then sets almost 1 1/2 hours after the sun. See if you
can detect the 1st-magnitude star Antares 4 degrees below Luna.
For watchful early observers, Venus begins its long-running morning
performance this week. Tomorrow the planet rises about 40 minutes before the
sun and comes up 7 minutes earlier each day thereafter. Venus remains a
"morning star" through mid July. As the planet emerges in the morning it appears
as a thin crescent. The phase is large enough to be seen in binoculars that are
held steady or mounted on a tripod. Find Venus just before sunrise and continue
following it into daylight. You will notice that the crescent becomes easier to
distinguish as the sky brightens.
Look for the three-day-old crescent Moon this evening. An hour after sundown it
perches 9 degrees (a fist) above the southwestern horizon. Examine the Moon
with binoculars or telescope. Notice how the surface looks rougher near the
terminator (currently the left side of the crescent). The effect is illusory; it is created
by the long shadows that fall on that part of the surface. If you were positioned on
the Moon near the terminator, you would be experiencing sunrise, which is the
reason for the long shadows. Continue watching the changing view over the next
several evenings with unaided eye and binoculars.
Tonight the Moon sits among the stars of the "teapot" pattern of Sagittarius. An
hour after sunset the Moon lies between two of the "handle" stars, 3rd-magnitude
Phi, 1 degree (2 moon diameters) to the lower right, and 2nd-magnitude Nunki
(Sigma), 1 degree to the upper left. Observe the Moon every half hour until it sets
and you'll be able to follow its approach to Nunki. Luna travels along its orbit
faster than most people realize, covering its own diameter every hour. When the
Moon is near a background star, such as Nunki tonight, its orbital motion
becomes apparent. For some locations, primarily northwestern U.S., the Moon
occults (covers) the star.
Take a careful look at the Moon with binoculars tonight. Can you detect the well-
defined crater on the terminator (left side) near the middle? It has a bright dot in
its center. The brilliant point is created by sunlight reflecting off the crater's central
mountain peak. The dark floor of the crater makes the peak dramatically stand
out. The crater is named after St. Theophilus, a patriarch of Alexandria who lived
in the late 4th and early 5th century A.D. The crater is 70 miles wide and more than
20,000 feet deep. To see a view of Theophilus from lunar orbit, visit this Apollo 16
web site: http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/a16_m_0692.html
Tonight the Moon stands less than 24 hours before First Quarter. It appears in
Capricornus, one of the fainter and less recognized zodiac constellations. That
constellation also contains two of the dim outer gas giant planets. Eighth-
magnitude Neptune sits 5 1/2 degrees above the Moon, while 6th-magnitude
Uranus is 18 degrees to the upper left. The sunlight reflecting from these
denizens of deep space is no match for the Moon's brilliance, so if you wish to
observe them, wait until Luna moves on. Tomorrow night note the 3rd-magnitude
star 4 1/2 degrees (9 moon diameters) to the Moon's upper left. Its name is Delta,
and this star points the way to Uranus, which lies 2 degrees to its upper left.
The Moon turns First Quarter at 3:52 p.m. EST. Today is Veterans Day in the U.S.
Although that tribute has no direct astronomical connection, it nearly coincides
with one of the cross-quarter days, the times halfway between the equinoxes and
solstices. In bygone eras, Halloween, All Saints Day, and Martinmas in Scotland
have all been associated with this cross-quarter time that marks the midpoint
between autumn and winter. The splendid Pleiades star cluster is also linked to
the period because it stands nearly opposite the sun in the sky. Rising at sunset
and setting at sunrise at the cross-quarter, the Pleiades provide a celestial
marker for the occasion. Look for the cluster low in the northeast as soon as the
sky gets dark.
Look for a 1st-magnitude star 15 degrees (fist and a half) below tonight's waxing
gibbous Moon and 13 degrees above the horizon (during twilight). Remember its
name? It was discussed here just about a month ago -- the last time the Moon
passed near it. The star is in Piscis Austrinus, the Southern Fish. It is likely the
least well known of the bright stars visible from mid-northern latitudes. Once you
learn of its existence, the star is not hard to find, since there are no other bright
stars in the vicinity. If you are familiar with the Great Square of Pegasus, you can
confirm the star's identity by noting that the right (western) side of the square
points nearly to Fomalhaut.
Mercury reaches superior conjunction overnight. The term "conjunction" indicates
that Mercury is nearly in line with the sun, as seen from Earth. The word "superior"
denotes that Mercury is beyond the sun, on the "back side" of the orbit. Note the
planet is also at conjunction (inferior) when it is between the sun and us. The
moment also marks Mercury's official passage into the evening sky. Although the
planet won't be visible to us as an "evening star" until mid December, Mercury
has crossed to the east side of the sun. In a few days it will be setting after sunset
even though we can't yet confirm that by observation.
Now that Venus is clearly visible low in the east-southeast dawn, four planets
appear in the morning skies. Twelve degrees above and slightly to the right of
Venus look for 2nd-magnitude Mars. Don't be confused by the 1st-magnitude star
Spica nearly midway between the two planets. Brilliant Jupiter perches two-thirds
of the way up in the south and bright Saturn sits halfway up in the west, 50
degrees (5 fists) to the lower right of Jupiter. The foursome of planets spans 123
degrees across the sky from east-southeast to west and neatly traces the
zodiacal path in doing so.
This year's approaching Leonid meteor shower is a not-to-be-missed event.
It could prove to be a rare experience. The frequency of "shooting stars" may
reach as high as one per second. Maximum occurs near 5:30 a.m. EST on November
19, with a smaller peak likely to take place 6 1/2 hours earlier, at 11 p.m.
November 18. To make the most of the opportunity, plan to observe from a dark,
dust-free location. The Moon is near full then, but its effect can be minimized
by shielding yourself from direct moonlight while still maintaining the broadest
view of the sky. Meteor shower forecasting is not exact science, so stay alert
to late-breaking reports. Plan to begin observing before the predicted times
to allow a margin of error. Most importantly, offer a sacrifice to the cloud
god to avoid his wrath. Leonid meteors will not penetrate a cloud layer. Staying
mobile enough to get out from under a cloud deck may be an even better strategy.
Meteor showers are created when the Earth passes through a cloud of dust
particles. These tiny pieces of matter, each similar in size to a grain of sand, are
heated to incandescence by the friction created when they plunge into our
atmosphere at 40-plus miles per second. The streak of light we observe signals
their demise. A comet -- in the case of the Leonids, Comet Tempel-Tuttle --
deposits the dust in our path. Comets can be imagined as dirty icebergs that
partially melt as they pass near the sun. The sloughed-off debris left in their wake
is the source of our meteor display. The more concentrated the dust stream, the
more spectacular the show. Evidence suggests this year's Leonid cloud is
dense.
The Leonid meteor "storm" reaches Earth in two waves of particles. The first is
predicted to occur at 11 p.m. EST tomorrow night. It has been referred to as the
European peak since western Europe and Africa are perfectly placed to catch the
brunt of the shower. The U.S. is just coming into "view" of the comet debris at that
time. Consequently the northeastern U.S. and eastern Canada will be in the
unique position where meteors from this first peak skim our planet, whizzing
through the Earth's atmosphere parallel to its surface. Observers in these favored
western hemisphere locations should see frequent meteors with especially long
trails.
The primary surge of Leonid meteors is expected to overtake Earth at
approximately 5:30 a.m. EST tomorrow morning. Estimates as high as 10,000
meteors per hour are predicted. One meteor per second is a reasonable
expectation. Don't wait until the last minute to go outdoors. Set your alarm an hour
earlier and watch the peak develop. Better yet, plan to stay up all night (and skip
work on Tuesday). Probably the most useful tactic to maximize your chance of
seeing the event is to carefully watch the weather reports and be prepared to
travel to the nearest patch of clear sky should you find yourself socked in. If all
else fails, you will probably be able to access the storm broadcast live on the
web.
Full Moon occurs at 8:34 p.m. EST. The Moon will be undergoing a penumbral
eclipse at that time. "Penumbral" indicates the Moon passes through only the
outer, fainter shadow of Earth. Frequently penumbral eclipses occur undetected
by casual observers. Because this penumbral eclipse is "deep" -- the Moon
barely misses the darkest shadow -- you may be able to detect a slight
duskiness at the upper left edge of the Moon. It will be most pronounce at
greatest eclipse, which occurs at 8:47 p.m. EST. The eclipse is visible from
Europe, western Africa, South America, and eastern North America
The Moon rises about half an hour after sunset. Once it clears the treetops, see if
you can detect Aldebaran, the brightest star in Taurus, the Bull. It sits 5 degrees
(10 moon diameters) to Luna's lower right. Examine the Moon with binoculars. A
slight roughness should be apparent on the upper right (east) edge of the Moon,
as the sunset terminator (shadow) begins working its way across the face of the
Moon. Notice, also, the bright craters with streaks (rays) emanating from them.
Tycho is on the lower right, and Copernicus is center left. Both are geologically
new craters, roughly 60 miles in diameter.
The Moon comes up in the east-northeast half an hour later than last night, so it
rises slightly more than an hour after sunset. Saturn follows Luna by about half an
hour. The two bodies are separated by 6 degrees (12 moon diameters) in the
evening. By dawn tomorrow the Moon has pulled within 3 degrees of the planet as
it passes north of Saturn. Tomorrow evening the pair rises almost two hours after
sunset. Then look for Saturn 7 degrees to the upper right of the Moon.
Venus, Spica, and Mars form a compact triangle in the morning sky. An hour
before sunup Mars is the highest and faintest of the trio. The 2nd-magnitude planet
hangs 20 degrees (2 fists) above the southeast horizon. First-magnitude Spica is
3 degrees to Mars' lower right. Brilliant Venus is 6 degrees below and slightly left
of Mars. Watch every morning to follow the changing pattern. Mars' motion is most
noticeable. In three mornings (25th) the Red Planet stands equidistant between
the other two bodies. By the end of the month Mars pulls within 2 degrees of
Venus.
Now that the Moon is rising a couple of hours after twilight, it is time to turn eyes to
the "deep sky objects." That's the term astronomers apply to those faint, generally
distant objects that require dark skies. Often revered by amateurs, these celestial
marvels usually need some background knowledge to appreciate the subtle
image that typically appears in the eyepiece. The Andromeda Galaxy, currently
visible high in the east, is a good example. To the novice, the faint smear of light
glimpsed in binoculars or telescope, often after significant effort to locate it, could
easily not seem worth the effort. But when you realize that fuzzy oval is the image
of a colossal galaxy containing 300 billion stars whose light has traveled 2 million
years to reach your eye, it becomes hard to look away.
The Messier Catalogue is probably the best-known record of deep sky objects.
Frenchman Charles Messier compiled the list in the late 1700's. Messier's
passion was comet hunting. While pursuing his quest, he discovered many dim
hazy objects that were not comets. To avoid continually being fooled by the same
objects, Messier produced a catalog of "false comets." Ironically, today Messier is
best known for the things he liked least. By the way, the Andromeda Galaxy, or
M31, is the 31st object listed in Monsieur Messier's Catalogue.
Look for the Moon tomorrow morning before sunrise. Jupiter is only 4 degrees (8
moon diameters) below it. Twelve degrees to the pair's left sits Regulus, the 1st-
magnitude star in Leo. Jupiter and its satellites seen through a telescope never
fail to captivate. The planet and moons look like a miniature solar system. Galileo
was the first to notice the resemblance. He announced this and other
revolutionary discoveries in a book published in 1610. Observing that Jupiter's
moons remained with the planet, as Jupiter itself traveled through space, was an
important discovery. It refuted the idea, popular at the time, that if the Earth moved,
the Moon would be left behind, so therefore the Earth must be stationary.
The Moon attains Last Quarter tomorrow morning at 10:46 a.m. EST. Earlier, an
hour before sunrise, the Moon appears 5 degrees to the upper left of Regulus, the
heart of Leo. Jupiter is 15 degrees to Luna's right. Twenty degrees the other
direction sits Denebola, a 2nd-magnitude star that represents the tuft of the lion's
tail. To the Moon's upper right is the circlet of fainter stars that represents Leo's
head. If you have trouble distinguishing the pattern, wait for the Moon to pass out
of the region and try again.
Tomorrow morning the Moon slips closer to Denebola, in Leo. At the start of dawn
it perches 9 degrees (a fist width) to the lower right of the star. Denebola is a
white star with a temperature of 15,000 degrees F. It is quite similar to Altair, the
star at the southern tip of the Summer Triangle, and Sirius, the brightest nighttime
star, located in Canis Major, the Big Dog. The primary difference between those
three stars is distance. Can you order the three according to their distance from
Earth?
The turkey is perhaps the most widely recognized symbol of our national day of
Thanksgiving. Many birds are represented among the constellations: swan,
eagle, dove, crow, phoenix, bird of paradise, crane, toucan, peacock, but no
turkey. By the way, if you don't recognize a number of those constellations, it's
because they are in the southern hemisphere, not visible from mid-northern
latitudes. The constellation most closely representing our Thanksgiving bird
might be Lyra. Today we know it as a lyre or harp, but several centuries ago it was
recognized as Vultur cadens, the swooping vulture. After spending today enjoying
friends and family, why not step outside tonight after dark, gaze halfway up in the
west, locate Vega, brightest star in Lyra, and give a nod to Vultur cadens.
If you have wondered lately about where the Big Dipper has gone, your north-
northwest horizon is probably obstructed. The Great Bear (Big Dipper) is now
beginning its period of hibernation, as Native Americans once taught. This time of
year the constellation dips low near the northern horizon, and emerges once
spring begins. If you currently are able to spot the Big Dipper low in the north-
northwest in early evening, get in the habit of looking for it each time you are out
after twilight over the next several months. Watching the Bear creep along the
horizon then begin to climb upward in the north-northeast provides reassurance
that winter is passing.
Even though tomorrow is Sunday, consider setting your alarm to arise before
dawn. The thin crescent Moon perches less than 2 degrees (about 3 moon
diameters) to the upper left of Venus -- a beautiful sight! In a telescope, Venus
will sport the same phase as the Moon, appearing like a tiny replica of Luna. As a
bonus, fainter Mars hovers in the vicinity, 2 degrees to Luna's right. The three
objects form a nearly equilateral triangle. The event takes place 20 degrees up in
the southeast an hour before sunrise. Hardcore observers may choose to get up
three hours before sunrise, just after Venus rises, to watch the Moon slowly crawl
past the planets.
Please send any comments, suggestions, or questions to
Thomas G. Ferguson:
fergus52@msu.edu
|