To the reader:
The Skywatcher's Diary for January 2003 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 January issue, please send a long,
self-addressed stamped envelope to:
January 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: January 2003
The new year begins with a morning planet parade. Four of the five naked-eye
planets appear before sunrise. With the sun rising so late this time of year, you
don't need to awaken especially early to attend the show, you just need to
remember to look. Two hours before sunup, here's the planetary lineup. Brilliant
Venus sits 16 degrees (one-and-a-half fist widths) above the southeast horizon.
Faint Mars is 5 degrees to the right and slightly higher. Bright Jupiter perches
halfway up in the west-southwest. Saturn hangs 8 degrees up in the west-
northwest.
New Moon occurs at 3:23 p.m. EST. For those learning to use a brand new
telescope, the Moon is the best nighttime target -- except now. New Moon is
nearly in line with the sun so it's hidden in the sun's glow. Furthermore, if we
could view it, we'd be looking at the shadowed side. Wait a couple of nights and
the Moon's appearance changes considerably. By Sunday or Monday night it will
be superb in a telescope. In the meantime, try Saturn, the brightest object in the
east an hour after sunset.
The Quadrantids, a meteor shower named for Quadrans Muralis, the Wall
Quadrant (a now-defunct constellation in northern Bootes), reaches its peak
overnight tonight. The maximum counts are somewhat variable, but the shower
usually produces an average of one meteor per minute. The short-lived peak
favors Europe this year. Best times for the U.S. are from 11p.m. local time until
morning twilight begins. Moonlight does not interfere.
The Earth passed perihelion early this morning, its closest approach to the sun
for the year -- about 91,406,000 miles. Aphelion, the farthest point, occurs six
months later (July 4th this year) at which time we'll be 94,511,000 miles away from
Sol. If you think, as many people do, that the seasons arise because of the
Earth's changing distance from the sun, stop and reconsider. Furthermore, how
would you explain the opposing seasons that exist simultaneously in the northern
and southern hemispheres?
The sun rises latest for the year today in mid northern latitudes. This evening the
crescent Moon appears 3 degrees (6 moon diameters) to the lower left of Delta, a
3rd-magnitude star in the pattern of Capricornus. It is the brightest star in this faint
constellation. Use binoculars to locate Mu, a 5th-magnitude star 3 degrees above
Delta. To the upper left, about a moon diameter (0.6 degrees), sits 6th-magnitude
Uranus. Sight the Moon to calibrate your binoculars' field of view, and then search
for the faint planet. It will be the brightest star-like object in Mu's immediate area
and may show a subtle green color.
Tonight's 4-day-old crescent Moon makes an exquisite sight for unaided eye,
binoculars, or telescope. The 1st-magnitude star about 15 degrees (30 moon
diameters) to the Moon's lower left is Fomalhaut, in the obscure constellation of
Piscis Austrinus, the Southern Fish. An hour after sunset the star sits 13 degrees
above the south-southwestern horizon. If there's any haze in the atmosphere,
Fomalhaut may appear dim and hard to find, but it is the brightest star in the
vicinity.
The Great Square of Pegasus sits about 30 degrees (3 fists) above and slightly
right of the Moon tonight. The pattern of 4 stars is the most recognizable part of
the constellation of Pegasus, the winged horse of Greek mythology. The stars are
all near 2nd-magnitude (one is technically 3rd -- can you tell which one?) and
make a respectable square that most people can easily pick out. The
constellation is also a key pattern of the autumn evening sky.
Tonight the Moon lies along the eastern edge of the Great Square of Pegasus.
Luna sits 20 degrees (2 fists) below the square's lower left corner. The Moon,
itself, is inside the boundary of Pisces, the Fishes. Most of this large
inconspicuous constellation lies above and to the left of the Moon. Tomorrow
night the Moon temporarily visits Cetus, the Whale, but returns to Pisces by Friday.
No, the Moon doesn't reverse course -- it's just a matter of the way the
constellation boundaries are drawn.
Saturn rises 2 hours before sunset, so it is conveniently located in the eastern sky
as dusk settles in. The ringed beauty continues to shine at near maximum
brilliance. Saturn is the brightest object in that part of the sky until Sirius, the
brightest nighttime star, rises in the east-southeast about 2 hours after the sun.
Jupiter follows shortly after Sirius, but in the east-northeast. By mid evening both
Jupiter and Saturn are well placed for casual observing.
First Quarter Moon occurs at 8:15 a.m. EST. It rises near east around midday, so
you should be able to find it throughout the afternoon as it progresses across the
southeastern sky. By then careful observers will notice that First Quarter has
already passed. In mid evening, the 2nd-magnitude star that appears about 20
degrees above the Moon is Hamal, the brightest in Aries, the Ram. Aries is the
last of the series of faint zodiac constellations that Luna has been traveling
through since New Moon. Next up for the Moon, 3 nights hence, is Taurus.
Mercury passes between Earth and sun today, a configuration astronomers call
"inferior conjunction." It's analogous to the Moon at New phase. The planet will
next become visible in the morning sky near the end of this month. Venus, the
other planet that travels between us and the sun, has just reached greatest
elongation. Earthlings now see the planet appearing farthest west of the sun in
the morning sky. Rarely these two planets can appear to cross in front of the sun,
an event known as a transit. Mercury transits the sun this year on May 7 and
Venus next transits on June 8, 2004.
Venus and Mars can be spotted every morning in twilight, low in the southwest. An
hour before sunrise Venus sits 21 degrees (2 fists) up. Mars, now 1st magnitude,
perches 9 degrees to the upper right of its dazzling sibling. Antares, the star
marking the heart of Scorpius, is 9 degrees below Venus. Antares appears about
a half magnitude brighter than Mars but significantly fainter than Venus. Watch
Antares seem to pass to the right of first Venus and then Mars as we move into
February.
The Moon now begins a several-day journey through the bright wintertime stars.
This evening look for Aldebaran, eye of Taurus, 10 degrees (a fist) to the lower left
of Luna. The beautiful Pleiades star cluster sits 5 degrees above and slightly left
of the Moon. Glare may make them hard to spot initially. If you have difficulty, use
binoculars to scan the region. Tomorrow night the Moon hops over Aldebaran and
sits between and above that star, on the lower right, and Saturn, to the lower left.
If you are somehow deficient in holiday celebrations, today's your chance to catch
up. It's the beginning of the year 2756 in the old Roman calendar instituted by
Julius Caesar in 46 BC. Caesar didn't get it quite right, so in 1582 Pope Gregory
modified the Julian Calendar into what has become known as the Gregorian
Calendar, the one most of us use today. Some consider the current calendar
system still untidy and continue to propose reforms. See, for example:
http://personal.ecu.edu/mccartyr/calendar-reform.html.
The Moon is next to Saturn tonight. About 7 moon diameters separate the two
objects in early evening. By the time Saturn sets tomorrow morning, about 2
hours before sunrise, the Moon will have drifted farther to the east and sit more
than twice that distance from the planet. Both bodies are within the boundaries of
Taurus, near the Bull's horns. The northern horn tip is marked by a 2nd-magnitude
star about 5 degrees (9 moon diameters) above the Moon, and the southern tip, a
magnitude fainter, is 1 1/2 degrees below Saturn. The Ringed Planet is currently
drifting westward (retrograde) relative to that star and continues to do so until the
latter part of February.
The gibbous Moon is now in Gemini, near the feet of the Twins. Tomorrow night it
slides below the "head" stars. The great hunter Orion stands to the Moon's lower
left in early evening. If you are unfamiliar with this magnificent pattern, look for the
three "belt stars," all 2nd magnitude and equally spaced. They are 30 degrees (3
fists) from the Moon and 20 degrees above the east-southeast horizon an hour
after sunset.
If you would like a star map that can help you identify these and other interesting
objects in the current sky, send a stamped, self-addressed envelope to Sky
Calendar, Abrams Planetarium, Michigan State University, East Lansing, MI
48824.
An hour after sunset the Moon sits to the lower right of the two brightest stars of
Gemini. Pollux is 7 moon diameters away, while Castor perches about 5 degrees
above Pollux. Overnight the Moon drifts below the twins. About 4 hours before
sunrise all three bodies, the two stars and Luna, appear in line and equally
spaced. Just before sunrise you'll be able to detect that the alignment is no
longer exact. The moon turns Full about that same time, and since full moons are
always opposite the sun, we know that Gemini must be the constellation currently
opposite the sun. Six months from now the sun will be in Gemini.
Full Moon occurred this morning at 5:48 a.m. EST. Tonight it rises close to the
time of sunset. In what direction would you expect it to rise? Remember that the
Full Moon is opposite the sun, so think about where the sun sets this time of year.
In winter the sun disappears over the horizon south of due west. Therefore, the
Moon should rise tonight somewhere near east-northeast. The pattern of when
and where various phases of the Moon appear is not hard to learn. The
knowledge can be acquired by simply being observant. A typical person long ago
knew much more about the lunar cycle than the average individual today.
Tonight Jupiter and the Moon rise within a few minutes of each other, about 1 1/2
hours after sunset. Initially they are separated by about 7 degrees (less than a
fist). As the night progresses and the two bodies slide across the sky, the gap
widens. If you see them before sunrise, notice the change. The separation
reaches 12 degrees (more than a fist) just before they set.
The Moon now rises after the end of evening twilight for mid northern latitudes.
We're moving into the two-week period of moonless evening skies, so its prime
time for observing faint objects from dark locations. Coincidentally, the Milky Way
Galaxy is now highest in early evening. It rises out of the southeast, runs
overhead, and then flows down into the northwest. If you haven't had a chance to
examine the hazy rim of our home galaxy in a while, try to find the opportunity to do
it by month's end, before the Moon reenters the picture.
If you can observe from a very dark location, look for the zodiacal light at the end of
astronomical twilight, 1 1/2 to 1 3/4 hours after sunset at mid northern latitudes.
The ghostly pyramid-shape can easily be mistaken for twilight glow, so check the
time carefully to be sure twilight has ended. The zodiacal light follows along the
zodiac (hence the name), which is currently rising out of the west-southwestern
horizon. The phenomenon is created by sunlight reflecting off specks of dust that
lie within the plane of our solar system.
Mercury begins a morning appearance that will continue through the first half of
February. Now shining at 1st magnitude, the planet can be glimpsed 45 minutes
to an hour before sunrise very low in the east-southeast. Use binoculars to assist
in picking it out of the twilight. If you are unsuccessful at first, continue trying every
clear morning. Mercury brightens about one magnitude by month's end, making it
easier to spot, and next week the planet will be highest during this appearance.
Tomorrow morning before sunrise the Moon sits 5 degrees (10 moon diameters)
above Spica, the brightest star in Virgo, the Maiden. Virgo is one of the largest
constellation patterns. The Moon has been in this constellation for the last two
mornings and will just be passing from Virgo on Saturday morning. The bright
star about 30 degrees (3 fists) above the Moon is Arcturus, in the constellation of
Bootes, the Herdsman. Both Bootes and Virgo are evening constellations of
spring.
With Mercury now visible in the morning sky, four planets appear before dawn.
Can you name the other three? Venus and Mars are close by Mercury. The fourth
is Jupiter, low in the west an hour before sunup. If one of your guesses was
Saturn, you've probably not been observing in the morning recently. Saturn sets
about 3 hours before sunrise. The Ringed Planet has now officially moved into
the evening sky, rising more than 3 hours before sunset.
The Moon reached Last Quarter phase this morning at 3:33 a.m. EST. If you look
at dawn, you'll find the "half moon" in the south. More fascinating, you'll be looking
toward the direction the Earth is traveling in its orbit. Pause while staring at the
Moon and try to imagine the Earth pushing against your feet, hurling you at 67,000
miles per hour toward the Moon. In about 3 1/2 hours you'll reach the place where
the Moon sits, as you are contemplating this scenario. Fortunately, the Moon will
have moved on by the time you get there.
Tomorrow morning before sunrise the waning crescent Moon sits less than 2
degrees (about 3 moon diameters) to the upper left of Mars. Six degrees below
the Moon and Mars hangs Antares, heart of Scorpius. The star's name comes
from Greek meaning "anti Ares." Ares is the Greek name for Mars, so the star's
title is frequently translated as "rival of Mars." The name refers to the star's red
color that makes it a twin image of the planet when the two objects are similar in
brightness, as they are now. Late this summer the comparison will not be as apt,
because the planet will outshine the star by nearly 4 magnitudes.
Tomorrow morning before sunrise the Moon perches 5 degrees to the lower right
of Venus. Although it's not a particularly close pairing of the two beauties, the
sight will be worth carving a moment from your early morning schedule to look at.
The following morning (Wednesday) the Moon drops to 11 degrees (a fist) to the
lower left of Venus. That morning is your last easy chance to catch the thin, old
Moon before it becomes New on February 1.
Saturn is well up in the east-southeast as dusk ends. The planet's rings are
tipped almost 27 degrees toward us, near the maximum possible. The angled
rings contribute to Saturn's current unusual brightness. They also prove an
alluring target for even a small telescope. Better scopes will be able to easily
decipher the Cassini Division, an apparent break that splits the larger ring in two.
The 17th century Italian/French astronomer Giovanni Cassini discovered this
3,000-mile-wide gap. A spacecraft, now headed toward Saturn, is also named
after him.
Tomorrow morning you still might catch a fleeting glimpse of the very old Moon. If
the sky is crystal clear, look 30 to 45 minutes before sunrise just to the left of
southeast, and almost on the horizon. Mercury will likely be easier to spot. It sits 6
degrees above the hairline crescent. Use binoculars and be patient. If you miss
Luna, you'll be able to see her next in the evening sky on February 2 or 3.
The planet Jupiter and Sirius, the brightest nighttime star, both rise at sunset, for
mid northern latitudes. An hour after sunset look for the star in the southeast and
the planet in the east-northeast. Can you determine which is brightest? Although
Sirius is the brightest star, Jupiter is about a magnitude brighter. The star resides
in Canis Major, the Great Dog, which explains its common nickname, the "dog
star." When Sirius is low in the sky it twinkles intensely, flashing in a rainbow of
colors. Take a close look some night. It's a sight to behold. Binoculars will
enhance the colors.
Passing through the overhead point of the sky in the early evening, for mid
northern latitudes, is the constellation of Perseus. It represents the hero of Greek
myth who tamed Pegasus, slew Medusa, and rescued Andromeda, which are
objects all represented in the sky. Perseus holds the snake-coiffured head of
Medusa. It is marked by a variable star called Algol that represents Medusa's evil
eye. The star varies between magnitude 2.1 and 3.3 over a 3-day period. We now
know the reason for its changing brightness. Algol is actually a pair of stars
orbiting one another. From our viewpoint they alternately pass in front of each
other, therefore causing the total brightness to fluctuate in a predictable manner.
Please send any comments, suggestions, or questions to
Thomas G. Ferguson:
fergus52@msu.edu
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