Abrams Planetarium Skywatcher's Diary
October 1998
To the reader:
The Skywatcher's Diary for October 1998 has been prepared by
Robert C. Victor. Credit to the author and to
Abrams Planetarium, the
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-t.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/
Bright evening planets: Jupiter (magnitude -2.9 to -2.7) dominates the
sky. It's in ESE to SE at dusk, higher as month progresses. Saturn
(mag. 0) rises at sunset on Oct. 23 and is up all night, at opposition (180
degrees from Sun). Look low in E at dusk, high in S in middle of night,
and low in W at dawn. Saturn stays 41 degrees E of Jupiter all month,
trailing it across night sky. See Oct. 3-6, Oct. 30-31. Use binoculars to
follow the Galilean satellites of Jupiter. Outermost Callisto, in its 17-day
orbit, appears farthest W of Jupiter Sept. 29, Oct. 15, Nov. 1, and
farthest E on Oct. 7 and 24. Ganymede, the brightest, is farthest W on
nights of Sept. 29, Oct. 7, 8, 14, 15, 22, 29, and farthest E on nights of
Oct. 4, 11, 18, 25. A telescope makes it easier to spot the inner moons
Io and Europa, and resolves details of Jupiter's cloud belts. This month
Saturn's rings are displayed 16 to 15 degrees from edge-on. Titan,
Saturn's brightest moon, appears farthest W of planet on nights of Oct.
2 and 18, and farthest E on nights of Oct. 10 and 26. Track Titan in its
16-day orbit.
Planets at dawn: Saturn sinks in W as month progresses. Mars is in E
to ESE. At magnitude +1.7 to +1.6, Mars is a little fainter than nearby
Regulus (+1.4); compare their colors. Mars-Regulus are separated by 3
degrees on Oct. 2, closing to 2 degrees on Oct. 4, 0.9 degree (closest)
on Oct. 7, then widen to 5 degrees apart on Oct. 15, 10 degrees on Oct.
23, and 15 degrees on Oct. 31 and Nov. 1.
Possible spectacular meteor shower this month: See Oct. 8 in Diary,
below.
Skywatcher's Diary: October 1998
On Friday, one-and-a-half hours before sunrise, face east and look
about 20 degrees above the horizon. There you'll see Mars 3 degrees
above the slightly brighter star Regulus, the heart of Leo, the Lion.
Watch these bodies change their relative positions in coming days.
The Cowboy Astronomer opens at 8:00 p.m. tonight at Abrams
Planetarium. Noted cowboy humorist Baxter Black narrates this
homespun jaunt through the night sky.
An hour after sunset, the waxing gibbous Moon is in SE, with bright
Jupiter in ESE, 20 degrees to Moon's lower left. Another hour later,
look for the first-magnitude star Fomalhaut 20 degrees below the
Moon, and the planet Saturn low in the east 41 degrees to Jupiter's
lower left. Watch the Moon change its position in relation to Jupiter and
Saturn over the next five evenings.
The Cowboy Astronomer, 8:00 p.m. tonight at Abrams Planetarium.
Low in ESE soon after sunset tonight, Jupiter is about 6 degrees to the
Moon's lower left, depending on your location. Follow the Moon and
Jupiter hourly, and watch the Moon gradually close in on Jupiter as the
night progresses. Two-and-a-half hours before sunup on Sunday,
they're still visible, low in WSW, while Mars is just 2 degrees above
Regulus low in eastern sky. From western U.S., the Moon passes
closely south of Jupiter in Sunday's morning hours.
Rusty Rocket's Last Blast, our family show, is presented 2:30 p.m.
Sundays at Abrams Planetarium. Our feature show, The Cowboy
Astronomer, is presented at 4 p.m. today. For information on our
shows, call (517) 355-4672.
A few minutes before sunset, as the Sun is about to rest on the horizon
just south of due west, can you also spot the nearly full Moon just risen
a few degrees south of due east? At nightfall, about 1-1/2 hours after
sunset, the Moon is in ESE with bright Jupiter about 10 degrees to its
upper right. Saturn is about 31 degrees to Moon's lower left.
Tonight's Full Harvest Moon rises just north of due east soon after
sunset. (From southern lower Michigan, the Moon rises 3 degrees north
of east within 20 minutes after sunset.) At nightfall, Jupiter is 25
degrees to Moon's upper right, while Saturn is 16 degrees to Moon's
lower left. An hour before sunup on Tuesday, the Moon is low in
western sky, with Saturn 11 degrees to its upper left. Mars and Regulus
are just 1 degree apart in east.
Watch moonrise this evening, some 10 degrees north of due east, an
hour after sunset. Note Saturn then 2 to 3 degrees to Moon's upper left,
and bright Jupiter some 40 degrees to their upper right. An hour before
sunrise on Wednesday, Moon is in WSW to W, with Saturn 5 degrees
lower right, while Mars and Regulus are just 0.9 degree apart in east.
Mars-Regulus appear closest that morning, with planet passing just
north (left) of star. Binoculars enhance their colors: red tint of Mars
contrasting with blue-white of Regulus.
Two hours after sunset, note Moon just risen between E and ENE, with
Saturn in east, 15 degrees to Moon's upper right. Bright Jupiter is in SE,
41 degrees upper right of Saturn.
Will there be a Draconid Meteor Storm tonight? There may be, if Earth
encounters a dense stream of particles from Comet Giacobini-Zinner. It
is now seven weeks before the Comet itself plunges through Earth's
orbital plane, a scant 3 million miles outside our orbit. (Don't worry,
Comet G-Z gets no closer to us than 79 million miles this time around!)
Twice previously in this Century, in 1933 and 1946, the Draconids have
produced spectacular brief meteor storms. The radiant of this meteor
shower (the direction from which these meteoroids approach Earth) is
near the head of Draco, high in NW at nightfall, between Vega and the
bowl of the Little Dipper. The speed of our encounter with these
particles is relatively slow (20 km/sec, or 45,000 mi/hr), because the
Comet and its attendant meteoroids travel in an orbit in roughly the
same direction as Earth. Compare that to November's Leonid meteors,
whose encounter speed relative to Earth is a sizzling 71 km/sec
(159,000 mi/hr). That's because the Leonids' parent Comet Tempel-
Tuttle has a retrograde orbit, and the meteoroids approach the Earth
head-on. There is no guarantee that exceptional numbers of meteors will
be seen on night of Oct. 8 or 9 (Draconids) or on the morning of Nov.
17 (Leonids), but many people will be watching! For more, visit the
website of the International Meteor Organization, at http://www.imo.net/
See also the article "A Surprise October Meteor Shower?" on pp. 100-
105 of the October 1998 issue of Sky & Telescope magazine.
Four hours after sunset tonight, the waning gibbous Moon is in east,
with first-magnitude Aldebaran, eye of Taurus, 7 degrees to its lower
left. Binoculars show stars of the V-shaped Hyades cluster between
Moon and Aldebaran. A telescope will show 4th-mag. Gamma Tauri,
the point of the "V", uncovered by the dark side of the Moon tonight at
10:08 p.m. in Honolulu; 1:51 a.m. PDT in Los Angeles; 3:21 a.m.
MDT in Denver; 4:51 a.m. CDT in Chicago; 5:57 a.m. EDT in East
Lansing MI; and 6:17 a.m. EDT in Boston. For more information on
occultations, check the website of the International Occultation Timing
Association: http://www.sky.net/~robinson/iotandx.htm
Four hours after sunset tonight, the waning gibbous Moon is in ENE,
with Aldebaran 7 degrees to its upper right. An hour before sunrise on
Saturday, look high in SSW to see Orion's shoulder, Betelgeuse, 13
degrees to Moon's lower left, and Aldebaran 11 degrees to Moon's
lower right.
On Sunday an hour before sunup: Moon high in S, with Betelgeuse 13
degrees lower right.
An hour before sunup on Monday, the Moon is high in SSE, with
Procyon, brightest star in Canis Minor the Little Dog, 14 degrees below.
Pollux, brightest star in Gemini, is 11 degrees to Moon's upper left.
Castor, the other twin, is 4-1/2 degrees upper right of Pollux. The Moon
is at Last Quarter phase, 90 degrees or one-quarter circle west of the
Sun. Follow the Moon in daytime until it sets in WNW after midday on
Monday.
On Tuesday an hour before sunrise, the fat crescent Moon is high in
SE, with Procyon 15 degrees lower right, and Pollux 13 degrees upper
right. Mars and Regulus, well up in ESE, have separated to 4 degrees
apart.
An hour before sunup on Wednesday, the waning crescent Moon is in
ESE, with Regulus, heart of Leo, 15 degrees lower left. Mars is 4-1/2
degrees lower left of Regulus. Compare colors and separation of the
Mars-Regulus pair with Pollux-Castor, high in south.
In ESE an hour before sunup on Thursday, the crescent Moon is
closely accompanied by Regulus to its lower left. Reddish Mars is just 5
degrees lower left of Regulus.
An hour before sunup on Friday, look just south of east for a pretty
arrangement of the Moon, a planet, and a star. In order from lower left
to upper right, they are the Moon, Mars, and Regulus. Mars-Regulus
are still within 6 degrees apart.
One hour before sunrise on Saturday, the crescent Moon, with its dark
side illuminated by earthshine, is a pretty sight low in the eastern sky.
Two other solar systems are easily visible: Saturn low in the west, and
Mars 16 degrees upper right of the Moon.
Sunday is the last morning for an easy view of the waning crescent
Moon. An hour before sunrise, look for the thin crescent low in the east.
Watch for the rising of the bright star Arcturus in ENE. The brightest
star is Sirius, in Canis Major the Greater Dog, in the south.
Last chance to see the old Moon: Using binoculars 40 minutes before
sunrise Monday, look for the very thin crescent about 6 degrees south
of east and 2 degrees above horizon. From northern U.S. the horns of
the crescent point directly up, because the Sun lies under the horizon
directly below. From lower Michigan, the Moon is 23 hours before
New. The Moon will be New on Tuesday at 6:09 a.m. EDT.
Mornings from now through November 2, the Moon will be absent
from the sky 1-1/2 hours before sunrise, providing a good opportunity
to observe the zodiacal light from very dark sites, where there is no
interference from artificial light. Face east just before the first evidence
of morning twilight begins to brighten the sky, and look for a very
large, softly luminous cone of light with its base near the horizon and its
axis near the ecliptic (near Mars and Regulus in Leo, extending toward
Cancer). The zodiacal light is caused by the reflection of sunlight off
dust particles which are concentrated in the plane of the solar system.
The dust particles were supplied by comets and by collisions of
asteroids. For more on this phenomenon, see
http://antwrp.gsfc.nasa.gov/apod/ap970826.html
Predawn skies are dark and moonless this week, ideal for observing
Orionid meteors.
First chance to see the young Moon: Using binoculars about 20 to 40
minutes after sunset, look for the slender crescent very low in WSW.
Observers in southern states will be favored to spot Mercury 5 or 6
degrees to Moon's lower left.
Find the first easy young crescent Moon low in WSW 30 minutes after
sunset. As the sky darkens, look for Antares, heart of Scorpius, low in
SW about 15 degrees to Moon's left.
On Friday an hour before sunrise, Mars is in ESE, 10 degrees lower
left of Regulus.
Forty-five minutes after sunset, look for the waxing crescent Moon low
in SW. Try for Antares 9 degrees to its lower left. Very low in east,
look for Saturn 41 degrees lower left of Jupiter. Tonight, three bodies,
in order Sun-Earth-Saturn, are arranged in a straight line in space. As
seen from Earth, Saturn appears at opposition, or 180 degrees from the
Sun, and is visible all night. This alignment of Sun-Earth-Saturn occurs
each time Earth passes between Saturn and the Sun, which happens at
intervals of about one year plus two weeks (next time: Nov. 6, 1999).
Look for Saturn in east at nightfall, high in S in middle of night, and in
west at dawn's first light. Saturn is now closer to Earth than it has been
since 1978 and brighter (mag. 0.0) than it has been since 1989. The
rings of Saturn are tipped about 15 degrees from edge-on.
Here's a chance to get closeup views of Jupiter and Saturn: Tonight and
Saturday, MSU Observatory is open for public viewing from 9:00 p.m.
until 11:00 p.m. if skies are clear, following the 8:00 p.m. showings of
The Cowboy Astronomer at Abrams Planetarium.
Daylight saving time ends in most of U.S. tonight, at 2 a.m. on Sunday
morning. Remember to set your clocks back one hour before retiring.
At nightfall, about 1-1/2 hours after sunset, look for the crescent Moon
in SW, with the Teapot of Sagittarius consisting of eight stars of 2nd
and 3rd magnitude to its lower left. In late December and early January,
the orbital motion of Earth makes the Sun appear to pass just north of
this asterism, rendering it invisible from Earth.
The Moon is in SSW an hour after sunset. Within 7 degrees below the
Moon is the 2nd-magnitude star Sigma in Sagittarius, brightest star in
the handle of the Teapot.
The Moon, nearing First Quarter phase, is almost half full in the south
at sunset. The Moon is a few degrees short of 90 degrees or a quarter-
circle east of the Sun. As darkness falls, look for a pair of 3rd-
magnitude stars, Alpha and Beta in Capricornus, just over 2 degrees
apart to the Moon's upper left. Binoculars easily show the upper one,
Alpha, appears as a double star. Its two components are actually at
widely different distances from Earth.
Tonight the Moon has passed First Quarter, and so it appear just over
half full and is just over a quarter-circle east of the setting Sun. When
the Moon is about half illuminated, telescopes and binoculars show the
Moon's surface features in wonderful detail.
Venus is now in superior conjunction, beyond the Sun. In December
Venus will become visible soon after sunset, and will remain in the
evening sky until early August 1999. You can follow its wanderings on
our Sky Calendar. Subscriptions are available for $9 per year, from
Abrams Planetarium, Michigan State University, East Lansing, MI
48824.
An hour after sunset, face SE to find bright Jupiter about 10 degrees to
the Moon's left.
One hour after sunset, bright Jupiter is in SE, some 4 or 5 degrees to
Moon's upper right. Telescope shows Jupiter's brightest moons
emerging from shadow just E of planet's disk: Io at 7:58 p.m. EST,
Ganymede at 9:33 p.m. Watch for a few minutes around these times.
