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(meteorobs) Sky & Tel Leonid Report
The short Leonid report is contained after the first stories on Uranus and
Jupiter:
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SKY & TELESCOPE'S NEWS BULLETIN
NOVEMBER 21, 1997
URANUS SHOWS OFF
Last July, astronomers used the Hubble Space Telescope to home in on
distant Uranus, which was then at opposition and thus relatively near the
Earth -- just 2.8 billion kilometers (18.8 astronomical units) away. Those
pictures, released on November 20th, reveal never-before-seen features in
the planet's northern hemisphere, the half that was hidden in shadow during
Voyager 2's 1986 flyby. According to Hubble investigator Heidi Hammel
(MIT), to the human eye the planet is still a somewhat bland, pale-blue
disk. But, at certain infrared wavelengths, methane gas in the planet's
atmosphere absorbs strongly; this causes the planet to appear dark and
high-altitude clouds bright. Several clouds appear to be girding Uranus at
a latitude near 30 degrees north, and the team will use the motion of these
features to time the planet's rotation at that latitude. Meanwhile, the
new Hubble images also clearly show the faint Uranian ring system, as well
as eight small satellites orbiting nearby.
JUPITER IN THE INFRARED
Astronomers released another planetary view on Thursday with Hubble's first
glimpses of Jupiter using the telescope's new Near Infrared Camera and
Multi-Object Spectrometer (NICMOS). The pictures were taken on September
17th by Reta Beebe of New Mexico State University and her colleagues.
Sensitive to a wavelength of methane, the pictures reveal bands of methane
clouds above Jupiter's main cloud deck and also show the planet's ring and
satellite Metis. Additional monitoring of Jupiter, coupled with visible-
light images, will allow astronomers to better understand the atmosphere of
the solar system's largest planet.
LEONIDS IN THE MOONLIGHT
While no one reported seeing anything close to the historically known
"meteor storms" from Last Monday night's Leonid meteor shower, many
observers were nevertheless impressed by many bright fireballs. According
to S&T contributor Stephen O'Meara, who was observing from the slope of
Hawaii's Mauna Loa, there were several instances when the fireballs came in
clusters of four or five. The brightest meteor, he reports, was magnitude -4
(as bright as Venus), and exploded with a brilliant white flash and left
a train that lasted more than 5 minutes despite the moonlight. His maximum
rate was between 13 and 14 hours Universal Time when he observed 41
meteors. The meteor trains varied in color from orange to green. Because
the Leonid shower's parent comet 55P/Tempel-Tuttle is due to reach
perihelion in February, meteor observers were hopeful that the display
would be extra intense. However, it is more likely that the "storm" may
come in 1998 and/or 1999.
PLANET PARADE
If you get an early start in the evening, you can make a sweep of nearly
all of the solar system's major planets. Venus through Neptune are well up
as the sky darkens with evening twilight, while Mercury is gradually
climbing above the southwestern horizon, approaching its greatest
elongation from the Sun at the end of November. Starting from Mercury and
heading east, you'll find Mars, Venus, Neptune, Uranus, Jupiter, and
Saturn. Only 13th-magnitude Pluto is largely out of reach, as it is quite
low above the west-southwest horizon.
THIS WEEK'S "SKY AT A GLANCE"
Some daily events in the changing sky, from the editors of SKY & TELESCOPE.
NOV. 23 -- SUNDAY
* Jupiter's Great Red Spot crosses the central meridian (the north-south
midline) of the planet's disk around 9:56 p.m. EST. (For a full list of the
Red Spot's transit times, see http://www.skypub.com/whatsup/redspot.html).
NOV. 24 -- MONDAY
* This is the time of year when the Big Dipper lies lowest in early
evening. If you're in the latitudes of the northern United States, look for
it lying horizontally above the north-northwest horizon after dusk. From the
Deep South it will be below the horizon altogether.
NOV. 25 -- TUESDAY
* Spica shines to the lower right of the waning crescent Moon before dawn
Wednesday morning.
NOV. 26 -- WEDNESDAY
* Jupiter's Great Red Spot transits the planet's central meridian around
7:27 p.m. EST.
* The eclipsing variable star Algol should be at minimum light, magnitude
3.4 instead of its usual 2.1, for a couple hours centered on 12:53 a.m.
Thursday morning EST. Algol takes several additional hours to fade and
rebrighten. For a complete schedule of Algol's eclipses for the next several
months, see http://www.skypub.com/whatsup/algol.html.
NOV. 27 -- THURSDAY
* Pluto is in conjunction with the Sun.
NOV. 28 -- FRIDAY
* Mercury is at greatest elongation, low in the southwest at dusk (to the
lower right of Venus and Mars).
* Jupiter's Red Spot transits around 9:06 p.m. EST.
NOV. 29 -- SATURDAY
* New Moon (exact at 9:14 p.m. Eastern Standard Time).
* Algol should be at minimum light for a couple hours centered around 9:42
p.m. EST.
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THIS WEEK'S PLANET ROUNDUP
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MERCURY is very low in the glow of sunset, far to the lower right of
Venus and Mars in the southwest.
VENUS is the bright light (magnitude -4.5) low in the southwest during and
after twilight.
MARS, quite dim at magnitude +1.1, is to the lower right of Venus.
JUPITER, in Capricornus, shines brightly (magnitude -2.3) in the south as
twilight fades. It moves lower in the southwest later in the evening and sets
around 10 p.m.
SATURN, in Pisces, glows at magnitude +0.4 in the southeast at dusk. It's
high in the south by 8 p.m.
URANUS and NEPTUNE are west of Jupiter, getting low after dark.
PLUTO is hidden behind the glare of the Sun.
(All descriptions that relate to the horizon or zenith are written for the
world's midnorthern latitudes. Descriptions that also depend on longitude
are for North America. Eastern Standard Time, EST, equals Universal Time
minus 5 hours.)
More details, sky maps, and news of other celestial events appear each month
in SKY & TELESCOPE, the essential magazine of astronomy. See our Web site at
http://www.skypub.com/. Clear skies!
SKY & TELESCOPE, P.O. Box 9111, Belmont, MA 02178 * 617-864-7360 (voice)
===========================================================================
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Sky at a Glance stargazing calendar are provided as a service to the
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===========================================================================
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James Richardson
Graceville, Florida
richardson@digitalexp.com
Operations Manager / Radiometeor Project Coordinator
American Meteor Society (AMS)
http://www.serve.com/meteors/
References: