Sky & Telescope News Bulletin - 12/28/96
Ron Baalke
SKY & TELESCOPE NEWS BULLETIN
DECEMBER 28, 1996
NEW YEAR's MILESTONE
If it feels like you're having a hot time on New Year's Day, maybe
that's because the Earth will be passing through the perihelion of its
orbit, its closest point to the Sun, on January 1st at 7 p.m. Eastern
Standard Time. We'll then be 147,095,000 km from the Sun -- about 3
percent closer than during June.
GALILEO @ EUROPA
NASA scientists are getting their first looks at images taken by the
Galileo spacecraft during its close flyby of the Jovian moon Europa
earlier this month. The point of closest approach, just 692 km away,
occurred on the 19th at 6:53 Universal Time. That's more than 200
times closer than the Voyager 2 spacecraft managed in 1979. But
getting Galileo's images to Earth has become a race against geometry,
as in little more than a week Jupiter will pass on the far side of the
Sun as seen from Earth, making radio contact extremely difficult. The
best views of Europa should resolve features the size of a large house
and may offer some hint as to whether a huge ocean of water lies
hidden beneath the moon's icy crust. The next flyby of Europa, on
February 19th, will be even closer -- just 587 km away.
HET's FIRST LIGHT
A new telescope at University of Texas's McDonald Observatory achieved
first light on December 10th. Astronomers focused light with the
Hobby-Eberly Telescope using seven of its eventual 91 hexagonal mirror
segments. Much as the Arecibo radio telescope does, the Hobby-Eberly
tracks celestial sources by moving its prime-focus assembly while the
primary mirror remains at rest. When complete, the $13.5-million
telescope will use its segmented 11-meter aperture and optical fibers
to feed light to several spectrographs. With a collecting area
slightly exceeding that of either Keck reflector on Mauna Kea, the
Hobby-Eberly should prove productive in the search for planets
orbiting other stars. Named for its principal benefactors, William P.
Hobby of Texas and Robert E. Eberly of Pennsylvania, HET is sponsored
by a consortium of three universities in the U.S. and two in Germany.
QUADRANTID METEORS
A waning crescent Moon will contribute slight interference for
observing the annual Quadrantid meteor shower. The shower has a sharp
maximum expected at about 11 hours Universal Time on January 3rd, well
timed for North American viewers. So if you can weather the morning
cold and are blessed with clear, dark skies, you may be treated to
perhaps one shooting star per minute at the shower's peak. The
Quadrantids' radiant in Bootes will be high in the sky as dawn
approaches.
THIS WEEK'S "SKY AT A GLANCE"
Some daily events in the changing sky, from the editors of SKY & TELESCOPE
DEC. 29 -- SUNDAY
* Some doorstep astronomy: Go out as dusk fades toward night and look
west-northwest. The brightest star there is Vega. The brightest high
above it is Deneb (somewhat fainter). At a greater distance to Vega's lower
left is Altair. They form the increasingly misnamed "Summer Triangle."
DEC. 30 -- MONDAY
* More doorstep astronomy: Look southwest around 7 or 8 p.m. The
brightest "star" there is pale yellowish Saturn. To Saturn's upper right
is the big, dim Great Square of Pegasus, balanced on one corner.
DEC. 31 -- TUESDAY
* Saturn's brightest moon, Titan, is visible with a telescope three or
four ring-lengths west of the planet this evening through Friday evening.
JAN. 1 -- WEDNESDAY
* Earth is at the perihelion of its orbit, its closest to the Sun for
the year (3.4 percent closer than at aphelion in July).
JAN. 2 -- THURSDAY
* Last-quarter Moon.
* We may be in for a good showing of the Quadrantid meteor shower early
Friday morning. The peak of the "Quads" is brief, lasting just a few hours;
this year it is predicted to arrive around 6 a.m. Eastern Standard Time,
excellent timing for North America. However, deviations of up to six hours
from the predicted time of maximum have been seen in past years.
There will be some moonlight interference. The waning Moon rises around 1:30
a.m. Friday morning to shine during the prime meteor-watching hours before
dawn. The shower's radiant is located halfway between the head of Draco and
the end of the Big Dipper's handle.
JAN. 3 -- FRIDAY
* For late-night observers, the eclipsing variable star Algol is at
minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple
of hours centered on 3:57 a.m. Eastern Standard Time Saturday morning.
Algol takes several additional hours to fade and rebrighten.
JAN. 4 -- SATURDAY
* Latest sunrise of the year (at 40 degrees north latitude).
============================
WEEK'S PLANET ROUNDUP
============================
MERCURY is hidden in the glare on the Sun.
VENUS is very low above the southeast horizon during dawn.
MARS, near the Leo-Virgo border, rises in the east around 11 p.m. and
shines high in the south before dawn. It appears more than halfway from
Regulus to Spica.
JUPITER sets in the southwest during dusk.
SATURN, in Pisces, is the brightest "star" high in the south during
dusk. It moves to the southwest later in the evening and sets by 11:30.
URANUS and NEPTUNE are disappearing into the sunset glow, east of Jupiter.
PLUTO is low in the glow of sunrise.
(All descriptions that relate to your horizon or zenith are written for the
world's midnorthern latitudes. Descriptions that also depend on your
longitude are for North America.)
Copyright 1996 Sky Publishing Corporation. S&T's Weekly News Bulletin
and "Sky at a Glance" stargazing calendar are provided as a service to
the astronomical community by the editors of SKY & TELESCOPE magazine.
Widespread electronic distribution is encouraged as long as this
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