To the reader:
The Skywatcher's Diary for October 2004 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 2004
Look to the north-northeast some evening toward the end of twilight. The bright
star Capella appears there only a few degrees above the horizon. If the air is clear
you may see the star flashing a rainbow of colors. In actuality Capella is a yellow
star, similar to our sun in color and temperature. But when viewed through the
Earth's turbulent atmosphere, it's intrinsic light is split up in prism-like fashion to
reveal a multitude of hues.
Whether or not you have followed Venus approaching the star Regulus, you'll
want to witness the climax tomorrow morning as Venus nuzzles within two-tenths
of a degree of the star. The pair rises about 3 hours before sunup, but since their
minimum separation occurs near sunrise on the west coast, the later you catch
the event the closer they will appear. The grouping is best seen through
binoculars.
Draco, the Dragon, is a relatively obscure constellation, despite its catchy name.
The head of the beast rests high in the northwestern sky at nightfall. Its long body
winds above the Little Dipper and the tail curls between the two Dippers. To
locate Draco's head, begin near overhead at bright star Vega. Move down toward
the middle of the Big Dipper. About 2 fists from Vega you will encounter a small
trapezoid shape composed of one 2nd (brightest in the constellation), one 3rd, one
4th, and one 5th-magnitude stars. The longest side of the trapezoid is half a fist in
length.
Following its "close encounter" with Regulus yesterday morning, Venus swiftly
pulls away from the star. This morning Venus hangs 1 degree below Regulus.
Tomorrow at dawn the separation is twice as great. A week from now when they
span 8 degrees (almost a fist), you won't even associate the two objects.
Mercury is at superior conjunction today. That's astronomer's shorthand for
indicating the planet has reached the far side of its orbit from Earth, nearly in line
with the sun. In rare instances the planet may travel directly behind the sun but
usually it slides above or below. Today Mercury passes a degree (2 sun
diameters) above Sol, but don't look for it. There's no chance of observing Mercury
in that proximity of the sun without specialized research equipment.
Last Quarter Moon occurs this morning at 6:12 a.m. EDT. Luna sits squarely in
Gemini. An hour before sunrise, look for the twin stars, Pollux and Castor, 9
degrees (a fist) to the lower left and 8 degrees to the left of the Moon, respectively.
The brighter starlike object 13 degrees to Luna's lower left is Saturn. Tomorrow
morning the planet appears 5 degrees to the Moon's lower right.
Tomorrow morning the fat crescent Moon appears within the faint constellation of
Cancer, the Crab. The brightest star in the immediate region is only 4th
magnitude. If you are out early enough, before twilight starts, look for the Beehive
star cluster 4 degrees (8 moon diameters) to the Moon's right. You will need
binoculars to find that sprinkling of stars.
Among ancient peoples, the zodiac constellation that appears above the eastern
horizon as evening twilight fades had special significance. It indicated to them
where they were in the yearly cycle of seasons. As days passed the constellation
changed at the rate of approximately one constellation per month. The technique
was more accurate for keeping track of the year than relying on the quixotic
weather signs. The approach still works today, but most folks prefer a wall
calendar.
Tonight at 11:31p.m. EDT the star Algol (Beta) in the constellation Perseus
reaches its minimum brightness. The star is a famous "eclipsing binary." In this
system, two stars orbit so that they periodically pass behind and in front of one
another. These cyclic "eclipses" produce a changing light output that we perceive
as a variable star. Algol dims from magnitude 2.1 to 3.3, and back again to 2.1,
over 2.87 days.
This morning the Moon creates an attractive isosceles triangle with Venus and
the star Regulus in Leo. The Moon-Venus pair is obvious in the east. Look for
Regulus 5 degrees (10 moon diameters) to the right and slightly above the Moon.
Tomorrow morning Luna slides 8 degrees to the lower left of Venus. Notice how
flat the crescent lies; it's tipped nearly horizontal. This orientation occurs each
autumn for the morning crescent and spring for the evening crescent at mid
northern latitudes.
If you have yet to catch Jupiter emerging out of dawn, tomorrow morning is an
ideal time to look. The thin crescent Moon hovers almost 5 degrees (10 moon
diameters) directly over the planet. An hour before sunup, Jupiter sits 3 degrees
above the horizon and 4 degrees south (right) of due east. It's also the last easy
chance to see Luna before New.
The Great Square of Pegasus is a well-known constellation figure of the autumn
skies. In the early evening, look for a large rotated square or diamond shape
about half way up in the east. The pattern extends approximately 15 degrees (11/2
fists) on a side. But hold on. One of the stars in the square doesn't belong to
Pegasus. The star at the left point of the diamond is Alpheratz (al FEE rats), also
known as Alpha in Andromeda.
The Moon becomes New at 10:48 p.m. EDT. A partial solar eclipse is associated
with this New Moon. Can you guess approximately where on Earth the eclipse
can be seen? Look at the time of New Moon. Since it's nighttime in the Eastern
time zone, the sun won't be visible there and so neither is the eclipse. The same
is true for the entire continental U.S. and Europe. This eclipse will be seen from
Northeastern Asia and the North Pacific Ocean.
The constellation Lacerta, the Lizard, resides between the well-known patterns of
Cygnus, the Swan, and Queen Cassiopeia, yet few people are aware of it. That's
probably because the reptile's brightest stars are only 4th magnitude, and it rests
in the midst of the Milky Way band among a multitude of faint stars. The
constellation's so well camouflaged, it could more accurately be called the
chameleon. Lacerta is a relatively new designation, one of several minor
constellations introduced by 17th-century Polish astronomer Johannes Hevelius.
The young Moon should be readily visible tonight even though it sets less than an
hour after sunset in the eastern U.S. Since Luna is almost 46 hours old (past
New), the crescent's prominent enough to be picked out even in the bright twilight.
Look for it 25 minutes after sunset, 3 degrees (six moon diameters) above the
horizon and 5 degrees to the left of west-southwest. The sighting of this crescent
marks the beginning of Ramadan, the Islamic month of fasting.
Can you still glimpse Antares, heart of the famous summer star pattern
Scorpius? The 1st-magnitude star sits low in the southwest at nightfall. For the
next two nights Luna will aid your search. Tonight Antares sits 8 degrees (almost
a fist) to the upper left of the Moon. During daylight tomorrow the Moon slips past
the star, so tomorrow night you will find Antares 6 degrees to the lower right of
Luna. Look 45 minutes to an hour after sunset.
Tonight's 4-day-old Moon makes a nice binocular target. The large gray oval just
above the center of the crescent is Mare Crisium, an ancient crater filled in with
lava rock. The less well-defined gray region below Crisium is Mare Fecunditatis.
To their left, sits Mare Tranquillitatis, only partially in sunlight. In a few hours the
sun will rise on the Apollo 17 site, located on the northern (upper) end of
Tranquillitatis.
The Moon moves through the constellation of Sagittarius over the next two nights.
Continue observing Luna with binoculars, making note of the changes you see
each night. Especially notice what happens to the craters' appearances. To
examine the craters in detail, you may want to steady the binoculars by leaning
against a wall or propping elbows on a tabletop. For best results, mount the
binoculars on a photographic tripod.
The Orionid meteor shower flares up during predawn hours over the next several
mornings. "Flares" is a relative term. An observer in a dark location will generally
see a meteor every 4 minutes on the average. Offsetting the fewer numbers,
these meteors are some of the fastest of the year. The "Orionid" designation
signifies that the meteors seem to radiate from a point in Orion's "club."
The Moon reaches First Quarter at 5:59 p.m. EDT. When at this phase, the Moon
trails the sun across the sky by about a quarter day, so you should expect it to
show up somewhere near south around sundown. Tonight it reaches due south
around an hour after sunset. Use binoculars to look for the faint kite-shaped
pattern 2 degrees (4 moon diameters) to Luna's right. The quartet of 4th and 5th-
magnitude stars is part of Sagittarius, near that constellation's eastern boundary.
Have you caught Mars emerging in dawn twilight yet? It's still difficult enough that
you'll probably need binoculars to see the planet. Forty-five minutes before
sunrise Mars sits 3 degrees above the horizon and 10 degrees (a fist width) to the
right (south) of due east. A line through the bright planets of Venus (brightest and
27 degrees above the horizon) and Jupiter (13 degrees up) points directly at Mars'
location.
To the lower right of Aquila, the Eagle, and above Sagittarius' "Teapot" pattern,
resides the faint constellation of Scutum, the Shield, another of Johannes
Hevelius' 17th-century creations. It was originally named Scutum Sobiescianum,
the Shield of Sobieski, referring to King Sobieski of Poland and patron of
Hevelius. Most amateur observers know the constellation as home of the
"Scutum Star Cloud," a particularly dense area of the Milky Way.
Venus and Jupiter now stand 13 degrees (just over a fist) apart in the eastern
dawn sky. Watch the separation between these bright beauties decrease over the
next two weeks. They reach minimum on the morning of November 5 when the
pair stands three-quarters of a degree (slightly over a moon diameter) apart. The
two brightest planets appearing that close together will make an eye-catching
sight.
"Eclipse season" is the term astronomers give to the time span during the year
when eclipses of the sun and moon are possible. There are usually two such
periods each year lasting several weeks. Today marks the middle point of one
eclipse season. It includes the partial solar eclipse that occurred on October 13,
visible from Asia, as well as the upcoming lunar eclipse on the 27th.
The extreme outer planets of the solar system, Uranus, Neptune, and Pluto, all
are above the horizon at the end of evening twilight. Uranus is found in the south-
southeast in Aquarius, 3 degrees below the star Theta. Neptune is due south in
Capricornus and 1 degree to the east of Theta in that constellation. Pluto sits low
in the southwest, technically in Serpens, but only 3 degrees to the upper left of 3rd-
magnitude Eta (also Sabik) in Ophiuchus. To locate the planets you will need
detailed finder charts.
The total lunar eclipse that occurs tomorrow evening is entirely visible from the
eastern two-thirds of the U.S., with the rest of the country catching various stages.
The eclipse is perfectly safe to watch at all times. Optical aid is unnecessary,
although binoculars can enhance the view. The color of a total lunar eclipse is not
exactly predictable beforehand, which adds to the appeal of the event. It can range
from dull gray to orange-red. Be sure to look for yourself tomorrow night.
The partial phase of the lunar eclipse begins at 9:14 p.m. EDT. Totality Ñ when
the Moon is completely within the Earth's shadow Ñ starts at 10:23 p.m. EDT.
The time of deepest eclipse is 11:04 p.m. Totality ends at 11:45 p.m., and the
partial eclipse is over by 12:54 a.m. EDT. The next total lunar eclipse similarly
visible from the U.S. occurs in February of 2008.
Although currently considered a morning planet, perched high in the south at
dawn, Saturn begins to make a foray into the night sky. It rises in the east-
northeast about 5 hours after sunset or roughly 11 p.m. local daylight time, and
just after the Gemini Twins. The planet comes up about 4 minutes earlier each
day or about 2 hours earlier per month. By mid January 2005 Saturn will rise as
the sun sets.
The Moon, two days beyond Full, rises less than 50 minutes after sunset. That's
an average of about 25 minutes later per night. This short span between sunset
and moonrise, occurring several nights in a row, is the essential characteristic of
the full moons of autumn Ñ the recent Hunter's Moon and last month's Harvest
Moon. Once tonight's Moon has climbed a bit, say 2 hours after sunset, look for
the Pleiades star cluster 4 degrees (8 moon diameters) to Luna's upper left. Use
binoculars.
Remember that most of the country converts to Standard Time at 2 a.m. tomorrow
morning, so set you clocks earlier by one hour before retiring tonight. Should you
be up at the appointed hour of 2 a.m., treat yourself to a preview of the winter sky.
Orion and associates then occupy the south to southeastern region, along with
the bright waning gibbous Moon and Saturn.
Venus and Jupiter are significantly closer than last week. The two planets sit 5
degrees (half a fist) apart in the east-southeastern dawn twilight. Faint Mars is
still emerging. Search for it with binoculars, in line with Venus and Jupiter, 15
degrees to the lower left and 3 degrees above the horizon between east and east-
southeast. Don't be misled by the star Spica. It's about twice as bright as Mars,
lower and to the right of the Red Planet.
Please send any comments, suggestions, or questions to
Thomas G. Ferguson:
fergus52@msu.edu
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