Sky & Telescope News Bulletin - August 24, 2001
Ron Baalke
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SKY & TELESCOPE'S NEWS BULLETIN - AUGUST 17, 2001
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For images and Web links for these items, visit http://www.skypub.com
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KUIPER OBJECT DETHRONES CERES
When Robert L. Millis (Lowell Observatory) and his Deep Ecliptic
Survey team recorded a distant, 20th-magnitude body in the head of
Scorpius last May, they realized that it was circling the Sun beyond
Neptune among a swarm of similar bodies collectively called the Kuiper
Belt. They also suspected that their discovery, designated 2001 KX76,
might rival 1 Ceres for the title of largest asteroid. But at the
time, the new object's orbit was too uncertain to know its precise
distance from Earth. Lacking that, the team could only guesstimate a
size based on its apparent brightness.
Now a fresh round of observations has allowed European astronomers to
pin down the orbit and, in turn, the object's diameter. Team leader
Gerhard Hahn (German Aerospace Center) believes that 2001 KX76 is at
least 1,200 km across, assuming that its surface has an albedo
(reflectivity) of 7 percent -- and 1,400 is not out of the question.
Determining the size more accurately will have to await measurements
at far-infrared wavelengths, which have not yet been made.
Pinning down the orbit required some sleuthing and a bit of luck.
First, members of Hahn's team used a 2.2-meter telescope in Chile to
update the object's position. Then they traced the motion of 2001 KX76
back in time using Astrovirtel, an electronic image archive. Luckily,
the object turned up in several images dating back to 1982. Armed with
two decades of data, Arno Gnaedig (a German amateur astronomer)
calculated that 2001 KX76 is currently 43.2 astronomical units (6.5
billion kilometers) from Earth. Its orbit is similar to that of Pluto,
locked in a dynamical resonance with Neptune that keeps it an average
of 39.9 a.u. from the Sun.
Millis has yet to propose a name for 2001 KX76. Brian G. Marsden, who
coordinates minor-planet observations for the International
Astronomical Union, says that by convention such "Plutinos" are given
names for figures associated with the underworld. "Hades" might be a
good choice, Marsden hints, because of its prominence in Greek
mythology.
SIR FRED HOYLE (1915-2001)
Sir Fred Hoyle, one of the most influential and controversial
scientists of the 20th century, died in Bournemouth, England, on
August 20th. He was 86.
Hoyle is perhaps best known for championing the Steady State theory of
cosmology. First published in 1948, this theory postulated that the
universe is always expanding, and that matter is created at precisely
the rate required to maintain a constant space density of galaxies. A
steady-state universe has no beginning or end and its overall
properties stay the same throughout time. Today the theory has been
discredited, replaced by the Big Bang origin of the universe -- a term
Hoyle himself coined and meant to be derogatory.
The British astronomer was instrumental in making one of the greatest
breakthroughs in modern science. It was Hoyle, who in 1956 and 1957,
helped develop the idea that nearly all elements heavier than helium
are synthesized in stars.
Hoyle was also known throughout the scientific community for
outlandish views on topics such as evolution and panspermia. He
questioned Charles Darwin's theory of natural selection, and believed
that life came to Earth from microbes living in outer space.
Hoyle was the first director of the Institute of Theoretical Astronomy
at the University of Cambridge, which he helped found. He was elected
as a Fellow of the Royal Society in 1957, knighted in 1972, and
received the Royal Swedish Academy's Crafoord Prize in 1997. He was
also a prolific science-fiction writer, authoring dozens of titles.
He is survived by his wife, Barbara, his son, Geoffrey, and his
daughter, Elizabeth Butler.
STAR IN CYGNUS GOES NOVA
On August 18th, when Akihiko Tago photographed a region in northern
Cygnus, he found the unmistakable image of a 9th-magnitude star at
right ascension 21h 03.0m, declination +48 deg. 46' (2000.0
coordinates). That's hardly a surprise for such a rich Milky Way field
-- except for one thing. The Japanese amateur's pictures on three
previous nights (August 15th, 16th, and 17th) showed nothing at the
same spot!
IAU Circulars 7686 and 7687 report that the "new" star brightened to
about magnitude 6.6 within 24 hours of its discovery, then declined
somewhat. A spectrum obtained by K. Ayani with the Bisei Astronomical
Observatory's 1.01-meter (40-inch) telescope shows blueshifted
absorption features, the earmarks of a violent cosmic explosion. The
Central Bureau for Astronomical Telegrams has designated the star Nova
Cygni 2001 No. 2. Another Japanese amateur, K. Hatayama of Niigata,
independently discovered the nova on the same night as Tago, but his
report was delayed.
On August 21st around 2:08 Universal Time, John Bortle of Stormville,
New York, found the star to be magnitude 8.1. Dozens of similar
reports have been received by the American Association of Variable
Star Observers. If this is a typical galactic nova, it may hover
around 8th or 9th magnitude for a few weeks before beginning a gradual
fade back into obscurity.
CANADIAN EYEBALLS NEW COMET
On Saturday, August 18th, the 200 participants at the Saskatchewan
Summer Star Party experienced an exciting moment as Canadian amateur
astronomer Vance Petriew announced he had discovered a comet -- just
hours before and while at the star party. Petriew had been observing
deep-sky sights with his new 20-inch Obsession reflector. About 3:30
a.m., he decided to swing over to M1, the Crab Nebula, but he never
got there. Star-hopping down from Beta Tauri, in the horns of Taurus,
he stumbled upon a faint smudge that he suspected immediately was out
of place.
Petriew checked his star charts to determine which galaxy he might be
seeing. Luckily, Richard Huziak of the Royal Astronomical Society of
Canada's Saskatoon Centre happened to walk by for the first time that
night, and Huziak knew there were none in that area of the sky. The
two observers plotted the object's position and continued to watch
until dawn. Telltale motion through the stars certified that this was
definitely a comet -- but was it already known?
A download of the latest orbital data later in the morning showed no
other known comet in the immediate area. "We suspected it could be
Comet Wild 4," Petriew notes, "but that was 4ř away." Around 6:00 a.m.
they called the Central Bureau for Astronomical Telegrams in
Cambridge, Massachusetts. "With so many star parties going on the same
weekend in the Northern Hemisphere I was sure someone else would have
already discovered the comet," Petriew says, not to mention major
sky-survey operations like LINEAR and NEAT. But the discovery proved
to be his alone, as he learned the next day.
It is a rare event these days for any amateur to discover a comet
visually (the previous one, Comet Utsunomiya-Jones, was spotted last
November). But to do so at a star party with 200 other friends and
fellow astronomers present to share the excitement was a rare moment
for everyone.Moreover, this is the first comet discovered at a major
star party since Donald Machholz found one during the 1985 Riverside
Telescope Makers Conference.
THIS WEEK'S "SKY AT A GLANCE"
Some daily events in the changing sky, by the editors of Sky &
Telescope.
AUG. 26 -- SUNDAY
* The Moon this evening forms the top of a flat triangle with Mars
(to its lower left) and Antares (to the Moon's lower right).
AUG. 27 -- MONDAY
* The orange "star" to the Moon's lower right this evening is Mars.
AUG. 28 -- TUESDAY
* The Moon, Mars, and Antares form a long, straight line in the
southern sky, from upper left to lower right.
AUG. 29 -- WEDNESDAY
* Turn a telescope on the waxing gibbous Moon tonight, and you'll
find the Sun rising on the Jura Mountains ringing the bay of Sinus
Iridum.
AUG. 30 -- THURSDAY
* The star nearly straight overhead after dark at this time of year
(assuming you live at a mid-northern latitude) is Vega -- a hot,
blue-white star 25 light-years away.
AUG. 31 -- FRIDAY
* The weak Alpha Aurigid meteor shower should reach its peak early
Saturday morning. Usually its meteors are quite few, but in 1935 and
1986 rates approached 30 per hour. Other such outbursts may have been
missed.
SEPT. 1 -- SATURDAY
* Arcturus is the brightest star in the west these evenings. Look a
third of the way from Arcturus up to Vega overhead to find the dim
semicircle of stars forming Corona Borealis, the Northern Crown. The
semicircle is open to the upper right.
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THIS WEEK'S PLANET ROUNDUP
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MERCURY is deep in the glow of sunset; look for it due west near the
horizon 20 or 30 minutes after sundown. The farther south you live the
better. Binoculars will help. (Don't confuse Mercury with Spica, which
is higher and well to the left in the west-southwest.)
VENUS (magnitude -4.0) is the brightest "Morning Star" shining in the
east at dawn. It's far to the lower left of bright Jupiter.
MARS is the brightest point in the southern sky after dark, shining
orange at magnitude -1.0. Fainter orange Antares twinkles far to its
right or lower right. For telescope users Mars appears 14 arcseconds
in diameter, but global dust-storm activity may still be obscuring
many of the planet's dark markings. A Mars observing guide and maps
are in the May Sky & Telescope, page 102.
JUPITER (magnitude -2.1) rises by about 2 a.m. daylight saving time.
It shines high in the east before and during dawn, midway between
dimmer Saturn to its upper right and brilliant Venus to its lower
left.
SATURN (magnitude -0.4) rises after midnight and glows yellow high to
Jupiter's upper right before and during dawn. Much closer to Saturn's
right is fainter orange Aldebaran. Above them are the Pleiades.
URANUS and NEPTUNE (6th and 8th magnitude, respectively) are in
Capricornus in the southeast during evening.
PLUTO (magnitude 14) is in Ophiuchus in the southwest in early
evening, to the upper right of Mars. Finder charts for Uranus,
Neptune, and Pluto are in the April Sky & Telescope, page 104, and at
lower resolution at
http://www.skypub.com/sights/moonplanets/outerplanets01.html .
(All descriptions that relate to the horizon or zenith -- including
the words up, down, right, and left -- are written for the world's
midnorthern latitudes. Descriptions that also depend on longitude are
for North America. Eastern Daylight Time, EDT, equals Universal Time
[GMT] minus 4 hours.)
More celestial events, sky maps, observing projects, and news of the
world's astronomy research appear each month in SKY & TELESCOPE, the
essential magazine of astronomy. See our enormous Web site and
astronomy bookstore at http://www.skypub.com/ . Clear skies!
SKY & TELESCOPE, 49 Bay State Rd., Cambridge, MA 02138 *
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