Abrams Planetarium
SKYWATCHER'S DIARY:
February 1996
To the reader
The Skywatcher's Diary for February 1996 has been prepared
by Robert C. Victor. Sometimes you can see next month's in advance
by looking in our archives. Credit to
Abrams Planetarium,
Department of Physics and Astronomy at
Michigan State University
would be appreciated. Our illustrated
Sky Calendar accompanies
the printed version of Skywatcher's Diary as it is sent monthly to
Michigan newspapers, but does not accompany this Internet version.
If you would like a sample copy, send your request with a self-
addressed, stamped envelope to
Sky Calendar
Abrams Planetarium
Michigan State University
East Lansing, MI 48824
A sample *Sky Calendar* of a past month is available over the Internet.
It can be accessed via a World-Wide Web browser such at Netscape or
Mosiac, directly at URL:
http://www.pa.msu.edu/abrams/novskycal.html
The Department of Physics and Astronomy at Michigan State University
continues to make *Skywatcher's Diary* available over the Internet. It
can be accessed via a World-Wide Web browser such as Netscape or
Mosiac, directly at URL:
http://www.pa.msu.edu/abrams/diary.html
The Skywatcher's Diary is also available via anonymous ftp at:
www.pa.msu.edu in the directory pub/swd/
Lunar and Planetary Highlights for February
At dusk in February, two planets are visible with unaided eye: Brilliant
Venus well up in WSW, with Saturn very close by on Feb. 1 and 2 (see
diary below). Saturn gets lower each day, and Venus a little higher, and
after Feb. 2, the gap between them widens by about one degree per day.
You may wish to perform the astrophotography project on the
conjunction of Venus and Saturn, described here last month, until about
the middle of February. Saturn's rings are exactly edgewise Feb. 11 and
begin to show us their lighted side Feb. 12 (see diary below), but the
telescopic image of Saturn so low in the sky isn't very steady. By Feb.
29, Saturn is almost gone.
Dawn skywatchers can see bright Jupiter low in SE sky an hour before
sunup. Mercury is visible near the horizon to Jupiter's lower left until
around midmonth. Look for a waning crescent Moon near the reddish
first-magnitude star Antares Feb. 13, near Jupiter Feb. 15, and to
Jupiter's lower left and near Mercury on the next two mornings.
Our first view of an evening crescent Moon occurs in early dusk on
Feb. 19, with the Moon climbing just to the upper right of Saturn on
Feb. 20 and just below brilliant Venus on Feb. 21. (If you're lucky
enough to be in Hawaii on Feb. 21, you can actually witness a rare
astronomical spectacular as the Moon occults, or hides, Venus.) The
Moon can be found first on one side, and then the other side, of
Aldebaran and the Hyades star cluster on consecutive evenings, Feb. 25
and 26.
-
- Well up in the WSW an hour after sundown tonight and Friday, Venus
and Saturn are within 1.3 degrees apart, the brightest and most compact
pairing of evening planets in 1996. The planets' closeness to each other
is only apparent, however. Venus is now 105 million miles from Earth,
and Saturn is over 9 times farther, or over 850 million miles beyond
Venus! Both planets can be viewed simultaneously through a telescope
at low power. Note Venus shows a gibbous disk, about three-fourths
illuminated. Increase the magnification to see the shadow of Saturn's
rings as a dark line of the face of the planet. More tomorrow.
About 45 minutes to an hour before sunrise these mornings, look for
bright Jupiter very low in SE. Look sharply for Mercury just above
horizon to Jupiter's lower left. The planets are 13 degrees apart for the
rest of this week; then their separation widens until Mercury disappears
into the morning twilight glow after midmonth.
-
- Tonight, Venus and Saturn are still within 1.3 degrees apart in the
WSW as darkness falls. We on Earth are now viewing Saturn's rings
from 0.5 degrees above (north of) their plane, while the Sun illuminates
them from 1.1 degrees below (south of) their plane. Accordingly, the
rings' unilluminated side is tipped slightly toward Earth and the rings
are virtually invisible to the sides of the planet.
In late November 1995 through early last month, the dark side of the
rings were more inclined, and through telescopes we could see them as
a dark line across the face of the planet. Now they're too close to edge-
on, and instead we see the rings' *shadow* on the face of the planet.
On Feb. 11, the rings will be exactly edge-on, and beginning Feb. 12
we may begin seeing the *illuminated* face of the rings, as a very
narrow bright line to both sides of the planet. More about that on
Feb. 11-13.
-
- In the WSW as the sky darkens, Saturn is nearly 2 degrees below
Venus. Saturn is getting lower each evening, Venus a little higher, and
the planets appear about a degree farther apart on each succussive
evening. The Moon is nearly Full tonight. Procyon, the Little Dog Star,
appears 16 degrees to the Moon's upper right, while the Dog Star itself,
Sirius, appears 26 degrees to Procyon's lower right. Sirius is the
brightest star in the night sky, though it is not as bright as Venus. A
good way to find Sirius is to recall that the Dog Star faithfully follows
Orion across the sky, and that the Hunter's belt points to it!
-
- The Moon, now past Full, rises about 15 degrees N of E within half an
hour after sunset. Wait until two hours after sundown and look for
Regulus, the heart of Leo, 11 degrees to the Moon's lower left.
-
- Two hours after sunset, the Moon has just risen a little north of east.
Just 5 degrees to the Moon's upper left is the star Regulus, heart of Leo,
the Lion, and 15th brightest of all the stars of first magnitude or brighter
which are visible from the northern U.S.
An hour before sunup on Tuesday, Regulus will appear in the west, 9
degrees to the Moon's right.
-
- Tonight at dusk, Venus shines brilliantly in WSW. Just 5 degrees
lower, the "star" of magnitude +1.2 is Saturn. This is nearly as faint as
Saturn ever gets, because its rings are now nearly edgewise. In the
years 2002 and 2003, when the rings are tipped at their greatest angle
and reflect much more light toward Earth, Saturn will reach magnitude -
0.3, 1-1/2 magnitudes brighter than now, and will appear four times as
bright as it does tonight.
-
- Now that the Moon rises in late evening, if you're in a place where the
sky is very dark, these are good nights for studying such dark-sky
phenomena as the zodiacal light and the Milky Way. To see the zodiacal
light at its best, face WSW when the sky first becomes fully dark,
(about 1-1/2 hours after sunset) tonight through Feb. 19, and look for a
softly luminous cone of light, nearly vertical with its base near the
horizon and its axis roughly along the zodiac which passes upward from
Saturn and Venus.
If you have a dry transparent sky and *can't* see the zodiacal light or
the Milky Way, your site may be suffering from *light pollution*, the
increased sky glow from excess light that does nothing to increase
useful nighttime illumination. It is light that sprays horizontally and
upward into the sky from poorly designed lighting fixtures. It is light
that glares into the eyes of motorists and homeowners, compromising
visibility, safety, and security.
Lack of awareness, rather than resistance, is the biggest problem in
contolling light pollution. The International Dark-Sky Association is a
tax-exempt, non-profit, membership organization dedicated to
overcoming this awareness problem, with the goal of preserving dark
skies, while at the same time maximizing the quality and efficiency of
outdoor lighting. IDA needs your help. To join this effort, or to obtain
further information on any aspects of the issue, write to the International
Dark-Sky Association, 3545 N. Stewart Avenue, Tucson, AZ 85716.
Memberships begin at $20 per year. Anyone who values the beauty of a
dark night sky should support this unique organization.
IDA has a homepage on the Internet. To access it, point your Web
browser at this URL:
http://www.darksky.org/~ida/index.html
-
- An hour before sunup on Friday, the waning gibbous Moon is in SW
with Spica, the spike of wheat in Virgo's hand, 9 degrees to the Moon's
left. Each day, the Moon moves an average of 13 degrees east against
background stars. After you see the Moon on Friday morning, try to
predict where it will appear at the same time on Saturday.
-
- Face SW to SSW an hour before sunup on Saturday, and look for first-
magnitude blue-white Spica 4 or 5 degrees to the Moon's lower right.
-
- Jupiter, low in SE an hour before sunrise, is the brightest "star" in the
current morning sky. On Sunday morning, Mercury reaches its greatest
angular distance from the Sun during this time around its orbit, 26
degrees. Look for Mercury low on the horizon, 18 degrees to lower left
of Jupiter.
-
- Brilliant Venus is well up in WSW at dusk. While the sky is darkening,
locate Saturn 10 degrees below Venus. Then, as soon as possible for
the clearest view, direct a telescope at Saturn. The rings are exactly
edgewise tonight and completely invisible, but you may be able to see
the rings' shadow as a dark narrow line on the face of the planet. Watch
nightly for changes as the rings become visible this week! More on
Monday and Tuesday.
On Monday an hour before sunup, the Last Quarter Moon is in the
south, about 90 degrees or one-quarter of a circle west of the Sun.
Antares is 16 degrees to the Moon's lower left. Note that the Moon's
left half is illuminated. Binoculars or a small telescope show striking
details near the Moon's terminator, or day-night boundary.
-
- Tonight at dusk, locate Saturn in WSW, 11 degrees below brilliant
Venus. Using a telescope, can you see, off to the sides of the planet,
any trace of the rings just one night after edge-on? Tipped just over 0.05
degree (3 arcminutes) from edgewise, the rings may appear as a very
narrow line of light piercing the planet -- Saturn kabob! As the rings tip
farther into view nightly, the line of light becomes brighter and easier to
see. The few evenings beginning tonight will be your last chance to see
the rings so close to edgewise until October 2038. That's because
during Earth's next edge-on views, in September 2009 and March
2025, Saturn will be lost in the Sun's glare.
-
- Tonight at dusk, the lighted face of Saturn's rings is tipped into view by
about 1/10 of a degree from edgewise -- twice as much as last night --
and should accordingly be easier to see. With unaided eye locate Saturn
in WSW at dusk, 12 degrees below brilliant Venus. Watching nightly
for changes, use a telescope to see the rings. For the clearest view,
*don't* wait until Saturn gets too low, later in the evening or later this
month.
-
- On Thursday about 3/4 hour before sunup, face SE for a beautiful sight:
The waning crescent Moon, partly sunlit and mostly earthlit,
accompanied by bright Jupiter just 4 degrees below. Mercury is still
visible, near the horizon 21 degrees to Jupiter's lower left.
-
- On Friday about 3/4 hour before sunrise, look for a slender crescent
Moon low in ESE to SE with two planets nearby: Bright Jupiter 14
degrees to Moon's upper right, and fainter Mercury near the horizon 10
degrees to Moon's lower left.
-
- Last chance to see the waning crescent Moon: On Saturday 45 minutes
before sunrise, look very low in ESE 29 degrees to Jupiter's lower left.
Binoculars give the best view of the delicate old crescent in the twilight
glow, within 36 hours before New for Michigan skywatchers. Can you
find Mercury flashing 7 degrees to the Moon's right?
-
- This weekend, Earth passes nearly between Regulus and the Sun, and
that star, marking Leo's heart, is visible all night. As you face Regulus
at this time of year, you are looking out of our solar system, directly
away from the Sun. Look for Regulus low in E at nightfall, high in S in
middle of night, and low in W at dawn's first light.
-
- The Moon is New today at 6:30 p.m. EST and can't be seen tonight.
-
- Half an hour after sunset a very thin young crescent Moon, just over 24
hours after New for Michigan skywatchers, is very low, just south of
due west, nearly 30 degrees lower right of Venus. As the sky darkens
and the Moon sinks toward the horizon, look for Saturn 11 degrees to
Moon's upper left and 19 degrees below Venus.
-
- A beautiful sight awaits us at dusk tonight and Wednesday. Tonight
brilliant Venus is well up on WSW with the 2-day-old crescent Moon
about 16 degrees to its lower right. (Be sure to look again on
Wednesday!) Note earthshine on the Moon's dark side, and Saturn 5
degrees to Moon's lower left. Tonight Saturn's rings are tipped 1/2
degree from edgewise, but the planet's low altitude at dusk may make it
difficult for telescope users to detect the narrow bright line of the rings
extending to the sides of the planet.
-
- Have you ever seen Venus in the daytime? Can you detect the Moon's
orbital motion within half an hour or less? Begin watching Moon and
Venus 20 minutes *before* sunset, when they're about 40 degrees up
in SW. Note their separation, then look every 20 minutes. Watch them
draw closer together until moonset.
From mid-Michigan at 6:00 p.m. EST (shortly before sunset), Moon
and Venus are just over 3-1/2 degrees apart. By 9:00 p.m. Venus is
only 2 degrees above the Moon's dimly earthlit upper limb.
From farther west in the U.S., the Moon creeps even closer to Venus
before they disappear over the western horizon. In a spectacular event
visible from the Hawaiian Islands, the Moon's leading dark edge
*occults* or covers Venus around 7:53 p.m. Hawaii time, or within 1
or 2 minutes later depending on the observer's location in the islands,
and reappears at the Moon's bright edge about an hour later.
-
- The Moon has overtaken Venus since last night, and early this evening
the brilliant planet gleams 9 degrees to Moon's lower right. Look for
Saturn another 22 degrees to Venus' lower right. At nightfall the long-
period variable star Mira, "the Wonderful", may be faintly visible to
the unaided eye, 16 degrees to the Moon's left. In March, Mira is
expected to reach peak brightness in its 11-month cycle. Typically,
Mira at its peak reaches about 3rd or 4th magnitude. In the next few
weeks, estimate Mira's magnitude by comparing it to the three stars in
the triangle 6 to 13 degrees above Mira. Alpha Ceti, the brightest and
highest star of the triangle, is of magnitude 2.6. Gamma is mag. 3.6,
and Delta, the faintest and lowest, is of mag. 4.1. More tomorrow on
observing stars which vary in brightness.
-
- At nightfall Venus is about 21 degrees to Moon's lower right. The
variable star Mira is 16 degrees lower left of Moon and 21 degrees
upper left of Venus. If you're interested in observing variable stars
andwould like to receive a chart for finding Mira and comparing its
brightness to surrounding stars, send a long, self-addressed, stamped
envelope to: Mira Finder Chart, c/o AAVSO, 25 Birch St., Cambridge,
MA 02138. The American Association of Variable Star Observers has a
Web page at: http://www.aavso.org
-
- The next few evenings, with the Moon close to half full, are ideal for
using binoculars and small telescopes for observing craters and other
lunar surface features, especially near the Moon's terminator, or day-
night boundary.
-
- The Moon, high in SSW at dusk, is approaching First Quarter phase,
when the halflit Moon would be 90 degrees or one-quarter circle east of
the Sun. Tonight, the Moon is nearly half illuminated. Note the star
Aldebaran 6 degrees to the Moon's east. Binoculars show the Hyades
cluster between the Moon and Aldebaran. Together, these stars complete
the head of Taurus, the Bull.
-
- The Moon, high in S at dusk, has passed First Quarter phase and
appears slightly more than half full. There are two reddish first-
magnitude stars near the Moon: Aldebaran, eye of Taurus, 6 degrees to
the Moon's lower right, and Betelgeuse, shoulder of Orion, 17 degrees
to Moon's lower left.
-
- Tonight at dusk, Betelgeuse, shoulder of Orion, appears in SSE, 11
degrees below the Moon.
-
- An hour after sunset, the Moon appears high in SE. Pollux and Castor,
the heads of the Gemini Twins, appear 18 degrees to Moon's left, while
Procyon, the Little Dog Star, appears 18 degrees to Moon's lower left.
Can you see the 2nd-magnitude star Alhena, or Gamma in Gemini,
within 2 degrees to Moon's right? Look hourly, and watch the Moon
pull away from the star as the evening progresses.
-
- Look high in SE an hour after sunset to find Procyon, the Little Dog
Star, 11 degrees to Moon's lower right. The Gemini Twins, Pollux and
Castor, are 12 and 16 degrees to Moon's upper left.
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