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发帖数: 298 | 1 ==================================================================
This Is SKY & TELESCOPE's AstroAlert for Minor Planets
==================================================================
NEXT MONTH'S FLYBY OF 2002 NY40
In mid-August, a newly discovered asteroid will pass close enough
to Earth that it should be easy to spot in small telescopes and
even binoculars. This object was first detected on July 14th by
astronomers using the LINEAR 1-meter survey telescope in New
Mexico, and |
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发帖数: 298 | 2 July 24, 2002 | It seems another comet is dissolving into nothingness, right
in front of astronomers' eyes. On July 13th, the NASA Jet Propulsion
Laboratory's Near Earth Asteroid Tracking program (NEAT) reported finding a
peculiar object with a faint coma. Calculations at the Minor Planet Center
soon revealed that the small body had the same motion as the periodic comet
57P/du Toit-Neujmin-Delporte but was separated from its nucleus by some 0.2
degree.
Alerted by those observations, a team of as |
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发帖数: 1994 | 3 Clearing Skies
Explanation: Clear evening skies are a welcome sight for stargazers worldwide, but clearing
skies are good too. Just such a glorious occasion was recorded in this dramatic photo taken by
Dominic Cantin during a recent gathering of Canadian astronomers at St-Nirie Observatory,
located about 60 kilometers southeast of the city of Quebec. Looking toward the west on July
13th, the exposure captured a distant lightning flash from a passing thunderstorm at the far
left. On the right, th |
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发帖数: 298 | 4 By David L. Chandler
July 29, 2002 | The whole thing cost just more than $200, it requires
virtually no maintenance except a once-a-month dusting, and it provides a
useful service that hasn't been widely available before. And it may just be
the start of something big: an all-sky, all-night fireball monitoring program.
Edward Albin, an astronomer at the Fernbank Science Center in Atlanta, built
and set up the video system two months ago on the roof of his home just
outside Atlanta (to avoid the c |
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发帖数: 298 | 5 July 28, 2002 | Astronomers continue to monitor a newly discovered Earth-
crossing asteroid, even though it now appears that no collision with our
planet is possible in 2019, as had been initially thought. Designated 2002
NT7, the wayward object was first spotted on July 9th by the LINEAR telescope
in New Mexico. Two weeks later NASA's orbital specialists at the Jet
Propulsion Laboratory had pegged the impact probability on February 1, 2019,
at about 1 in 250,000, whereas Italian dynamicists put |
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发帖数: 1994 | 6 Henize 3-401: An Elongated Planetary Nebula
Explanation: How do dying stars eject their outer layers? Stars that create elegant planetary
nebulas like Henize 3-401, pictured above, are not unusual, causing speculation that, one day,
our own Sun may look like this. Henize 3-401 is one of the most elongated planetary nebulas
yet discovered, a particularly odd feat for a seemingly round star. Perhaps, some astronomers
hypothesize, the elongated shape gives a clue to the expulsion mechanism. Genesis |
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发帖数: 1994 | 7 The Galactic Center - A Radio Mystery
Explanation: Tuning in to the center of our Milky Way galaxy, radio astronomers explore a
complex, mysterious place. A premier high resolution view, this startlingly beautiful picture
covers a 4x4 degree region around the galactic center. It was constructed from 1 meter
wavelength radio data obtained by telescopes of the Very Large Array near Socorro, New
Mexico, USA. The galactic center itself is at the edge of the extremely bright object |
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发帖数: 1994 | 8 Gomez's Hamburger: A Proto-Planetary Nebula
Explanation: What, in heaven, is that? Sometimes astronomers see things on the sky they
don't immediately understand. In 1985 this happened to Arturo Gomez, and the object became
known as Gomez's Hamburger for its distinctive yet familiar shape. After some investigation,
the object was identified as a proto-planetary nebula, a gas cloud emitted by a Sun-like star just
after its central hydrogen fuel has all been fused to helium. Gomez's Hamburger is on |
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发帖数: 1994 | 9 Cas A Supernova Remnant in X-Rays
Credit: John Hughes et al. (Rutgers), NASA / CXC / SAO
Explanation: The complex shell of a star seen to explode 300 years ago is helping
astronomers to understand how that star exploded. This Chandra Observatory image of
supernova remnant Cassiopeia A (Cas A) shows unprecedented detail in three x-ray colors.
The relationship between brightness, color, and position of material in the image indicates
where in the star this material was just before the |
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发帖数: 1994 | 10 Semeis 147: Supernova Remnant
Credit & Copyright: Steve Mandel
Explanation: It's easy to get lost following the intricate filaments in this stunningly detailed
image of faint supernova remnant Simeis 147. Seen towards the constellation Taurus it
covers nearly 3 degrees (6 full moons) on the sky corresponding to a width of 150 light-years
at the stellar debris cloud's estimated distance of 3,000 light-years. On three separate nights
in December 2001 and January 2002 astronomer |
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发帖数: 1994 | 11 X-Rays From Tycho's Supernova Remnant
Credit: SAO, CXC, NASA
Explanation: In 1572, Danish astronomer Tycho Brahe recorded the sudden appearance of
a bright new star in the constellation Cassiopeia. The new star faded from view over a period
of months and is believed to have been a supernova, one of the last stellar explosions seen in
our Milky Way galaxy. Now known as Tycho's Supernova Remnant, the expanding debris
cloud is shown in this detailed false-color x-ray image fro |
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发帖数: 1994 | 12 Hoag's Object: A Strange Ring Galaxy
Credit: R. Lucas (STScI/AURA), Hubble Heritage Team, NASA
Explanation: Is this one galaxy or two? This question came to light in 1950 when
astronomer Art Hoag chanced upon this unusual extragalactic object. On the outside is a ring
dominated by bright blue stars, while near the center lies a ball of much redder stars that are
likely much older. Between the two is a gap that appears almost completely dark. How Hoag's
Object formed remains unknown, alt |
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发帖数: 6 | 13 “new astronomer, skywatching today" by popular science
非常浅显易懂，图文并茂 |
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发帖数: 1994 | 14 V838 Mon: Mystery Star
Credit: Lisa Crause (Univ. Cape Town), Warrick Lawson (Australian Defence Force
Academy)
Explanation: A leading candidate for the most mysterious star found in recent times is
variable star V838 Monocerotis. At a distance of about 8,000 light-years, V838 Mon was
discovered to be in outburst in January of this year. Initially thought to be a familiar type of
classical nova, astronomers quickly realized that instead, V838 Mon may be a totally n |
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发帖数: 339 | 15 NASA's Hubble Space Telescope has measured the
largest object in the solar system ever seen since the discovery of Pluto 72
years ago.
Approximately half the size of Pluto, the icy world 2002 LM60,
dubbed "Quaoar" (pronounced kwa-whar) by its discoverers, is the
farthest object in the solar system ever to be resolved by a telescope.
It was initially detected by a ground-based telescope, as simply a
dot of light, until astronomers aimed the powerful Hubble telescope at it.
Quaoar is about 4 billi |
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发帖数: 1994 | 16 Black holes, like ill-mannered diners, let out a belch after wolfing down a meal. Now for the first time,
an astronomer says he has detected this cosmic burp--in the form of gas rapidly escaping a black
hole that has just swallowed a star.
The biggest appetites belong to quasars--supermassive black
holes at the cores of distant galaxies. As gas and stars are
violently sucked in |
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发帖数: 1994 | 17 At the Center of the Milky Way
Credit: Rainer Schvdel (MPE) et al., NACO, ESO
Explanation: At the center of our Milky Way Galaxy lies a black hole with over 2 million
times the mass of the Sun. Once a controversial claim, this astounding conclusion is now
virtually inescapable and based on observations of stars orbiting very near the galactic center.
Using one of the Paranal Observatory's very large telescopes and the sophisticated infrared
camera NACO, astronomers patiently follo |
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发帖数: 1994 | 18 Journey to the Center of the Galaxy
Credit: MSX, IPAC, NASA
Explanation: In Jules Verne's science fiction classic A Journey to the Center of the Earth,
Professor Hardwigg and his fellow explorers encounter many strange and exciting wonders.
What wonders lie at the center of our Galaxy? Astronomers know of some of the bizarre
objects which exist there, like vast cosmic dust clouds, bright star clusters, swirling rings of
gas, and even a supermassive black hole. Much of the G |
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发帖数: 1994 | 19 NGC 6369: The Little Ghost Nebula
Credit: Hubble Heritage Team, NASA
Explanation: This pretty planetary nebula, cataloged as NGC 6369, was discovered by 18th
century astronomer William Herschel as he used a telescope to explore the constellation
Ophiucus. Round and planet-shaped, the nebula is also relatively faint and has acquired the
popular moniker of Little Ghost Nebula. Planetary nebulae in general are not at all related to
planets, but instead are created at the end of a |
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发帖数: 1285 | 20 Explanation: The Hubble optical image on the left shows NGC 6240 in the
throes of a titanic galaxy - galaxy collision 400 million light-years away.
As the cosmic catastrophe plays out, the merging galaxies spew forth distorted
tidal tails of stars, gas, and dust and undergo frantic bursts of star
formation. Using the orbiting Chandra Observatory's x-ray vision to peer
within the bright central regions of NGC 6240 astronomers believe they have
uncovered, for the first time, not one but two enormo |
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发帖数: 1994 | 22 Images GRB 021211
Credit: P. Wozniak, W.T. Vestrand, et al., RAPTOR Project, LANL
Explanation: On December 11 astronomers found one of the brightest and most distant
explosions in the Universe - a gamma-ray burst - hiding in the glare of a relatively nearby star.
The earliest image of the burst's visible light was caught by an earthbound RAPTOR (RAPid
Telescopes for Optical Response). The two exposures inset above were taken by a RAPTOR
unit about 65 seconds (left) and 9 minutes (top right) afte |
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发帖数: 1994 | 23 A Year of Assessing Astronomical Hazards
Drawing Credit: Dan Durda (SWRI)
Explanation: Could an asteroid destroy civilization on Earth? Mountain-sized space rocks
could potentially impact the Earth causing global effects, and perhaps even be mistaken for a
nuclear blast of terrestrial origin. Such large impacts are rare but have happened before.
Modern telescopes have therefore begun to scan the skies for signs of approaching celestial
hazards. Over the past year, projects suc |
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发帖数: 1994 | 24 X-Rays from the Galactic Core
Credit: Fred Baganoff (MIT), Mark Morris (UCLA), et al., CXC, NASA
Explanation: Using the orbiting Chandra X-ray Observatory, astronomers have taken this
long look at the core of our Milky Way galaxy, some 26,000 light-years away. The spectacular
false-color view spans about 130 light-years. It reveals an energetic region rich in x-ray
sources and high-lighted by the central source, Sagittarius A*, known to be a supermassive
black hole with 3 million times th |
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发帖数: 1994 | 25 SEATTLE--Do gravity's tentacles cross space at the speed of light? Albert Einstein thought so, and two scientists now claim to have proved him right. Their results, described as the first measurement of gravity's speed, is based on observations of
Jupiter bending the light from a quasar. However, some physicists think the research--announced here on 7 January at a meeting of the American Astronomical Society--has fatal flaws.
Isaac Newton thought gravity acted instantaneously, but Einstein's gen |
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发帖数: 1994 | 26 The Heart in NGC 346
Credit: Y.Nazi (Universiti de Lihge) et al., CXC, NASA
Explanation: Yes, it's Valentine's Day (!) and looking toward star cluster NGC 346 in our
neighboring galaxy the Small Magellanic Cloud, astronomers have noted this heart-shaped
cloud of hot, x-ray emitting gas in the cluster's central region. The false-color Chandra
Observatory x-ray image also shows a strong x-ray source just above the heart-shaped cloud
which corresponds to HD 5980, a remarkable, massive |
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发帖数: 1994 | 27 Comet NEAT in Southern Skies
Credit & Copyright: Noel Munford (Palmerston North Astronomical Society, New
Zealand)
Explanation: After last month's dramatic swoop past the Sun, Comet NEAT (C/2002 V1)
appeared as a naked-eye comet, emerging from the evening twilight in planet Earth's southern
skies. On March 1st, New Zealand photographer Noel Munford captured this telephoto view
of the outbound comet close to the southwestern horizon against the faint stars of the |
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发帖数: 1994 | 28 Solar Sail
Credit: NASA / MSFC Illustration
Explanation: Nearly 400 years ago astronomer Johannes Kepler observed comet tails blown
by a solar breeze and suggested that vessels might likewise navigate through space using
appropriately fashioned sails. It is now widely recognized that sunlight does indeed produce a
force which moves comet tails and a large, reflective sail could be a practical means of
propelling a spacecraft. In fact, the illustration above represents one con |
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发帖数: 1994 | 29 WIRO at Jupiter
Credit: A. Kutyrev (SSAI/GSFC), D. Rapchun(GST/GSFC), J. Norris(NASA/GSFC)
R. Canterna & R. Martin (U Wyoming)
Explanation: Gazing out over the mountaintops from the Wyoming InfraRed Observatory
(WIRO), astronomers recently recorded this bizarre looking image of the solar system's
ruling planet, gas giant Jupiter. The false-color picture is a composite of images taken to test a
sophisticated digital camera operating at liquid helium temperatures and sensitive |
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发帖数: 1994 | 30 Jupiter's Great Dark Spot
Credit: Cassini Imaging Team, Cassini Project, NASA
Explanation: Seventeenth century astronomer Giovanni Domenico Cassini was an astute
observer of Jupiter's Great Red Spot. So it seems only fitting that his namesake, the Cassini
spacecraft, has enabled detailed observations of another planet-sized blemish -- Jupiter's
Great Dark Spot. Unlike the Red Spot, the Great Dark Spot lies near Jupiter's north pole and
seems to appear and disappear over periods of m |
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发帖数: 1994 | 31 Sunrise Analemma
Credit & Copyright: Anthony Ayiomamitis
Explanation: Astronomically speaking, at the Equinox on March 21, 0100 UT (March 20,
8:00 PM ET) the season changes. For this Equinox the Sun rises due east as it crosses the
celestial equator heading north. In celebration, consider this spectacular sunrise analemma!
An analemma is the figure-8 loop you get when you mark the position of the Sun at the same
time each day throughout the year. In this remarkable case, 38 separ |
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发帖数: 1994 | 32 Beijing Ancient Observatory
Credit & Copyright: Judy Tobin
Explanation: Did observatories exist before telescopes? One example that still stands today
is the Beijing Ancient Observatory in China. Starting in the 1400s astronomers erected large
instruments here to enable them to measure star and planet positions with increasing
accuracy. Pre-telescopic observatories throughout the world date back to before recorded
history, providing measurements that helped to determine when |
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发帖数: 1994 | 33 M106 in Canes Venatici
Credit: Bernie and Jay Slotnick, Adam Block, AOP, NOAO, AURA, NSF
Explanation: Close to the Great Bear (Ursa Major) and surrounded by the stars of the
Hunting Dogs (Canes Venatici), this celestial nebula was discovered in 1781 by the metric
French astronomer Pierre Mechain and later added to the catalog of his friend and colleague
Charles Messier as M106. Modern deep telescopic views reveal it to be an island universe -- a
spiral galaxy around 30 thousand light-year |
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发帖数: 612 | 34 发信人: asteroid (小行星), 信区: Astronomy
标 题: [网址] 2003年水星凌日（英文）
发信站: BBS 水木清华站 (Wed Apr 30 14:38:29 2003), 转信
http://sunearth.gsfc.nasa.gov/eclipse/OH/transit03.html
2003 Transit of Mercury
by Fred Espenak
Published in Observer's Handbook 2003, Royal Astronomical Society of Canada |
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发帖数: 1994 | 35 A Tale of Two Nebulae
Credit & Copyright: Brian Lula
Explanation: This colorful telescopic view towards the northern constellation Lyra reveals
dim outer regions around M57, popularly known as the Ring Nebula. While modern
astronomers still refer to M57 as a planetary nebula, at one light-year across M57 is not a
planet but the gaseous shroud of a dying sun-like star. Roughly the same apparent size as M57,
the fainter, often overlooked barred spiral galaxy IC1296 is at the l |
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发帖数: 1994 | 36 Eclipsed Moon Montage
Credit & Copyright: Sebastien Gauthier
Explanation: After watching this month's lunar eclipse, amateur astronomer Sebastien
Gauthier carefully composed this montage of telescopic images of the Moon sliding through
planet Earth's shadow. While the deepest part of the total eclipse corresponds to the central
exposure, the play of light across the lunar surface nicely demonstrates that the planet's
shadow is not uniformly dark as it extends into space. In fac |
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发帖数: 1994 | 37 Ring of Fire from Cape Wrath
Credit & Copyright: Hans Coeckelberghs
Explanation: If the Moon's apparent diameter is not quite large enough to cover the Sun
during a solar eclipse, an annular eclipse can be the result -- a spectacle of silhouetted Moon
surrounded by a solar "ring of fire". Just such a view was possible for observers in the far
northern hemisphere as the new Moon slid across the solar disk on May 31st. Still, for
astronomical adventurers at Cape Wrath on the north |
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发帖数: 1994 | 38 HD70642: A Star with Similar Planets
Illustration Credit & Copyright: David A. Hardy, PPARC
Explanation: Astronomers have discovered a planetary system more similar to our own
Solar System than any known previously. The bright star HD70642, visible with binoculars
toward the constellation of Puppis, was already known to be a star like our Sun. Now a planet
with twice Jupiter's mass has been discovered in a nearly circular orbit at approximately half
the orbital distance of Jupiter. Su |
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发帖数: 1994 | 39 Dumbbell Nebula Halo
Credit & Copyright: Robert Gendler
Explanation: In 1764, French astronomer Charles Messier sighted this gorgeous cosmic
cloud which he described as an oval nebula without stars. Cataloged as M27, it is now
popularly known as the Dumbbell Nebula, not for its substandard academic performance but
for the elongated shape, like a bar with weights on each end, which first caught Messier's eye.
This deep image of the bright planetary nebula does reveal the Dumbel |
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发帖数: 1994 | 40 A Beautiful Trifid
Credit & Copyright: Jim and Janet Castano, Adam Block, NOAO, AURA, NSF
Explanation: The beautiful Trifid Nebula (aka M20), a photogenic study in cosmic contrasts,
lies about 5,000 light-years away toward the nebula rich constellation Sagittarius. A star
forming region in the plane of our galaxy, the Trifid alone illustrates three basic types of
astronomical nebulae; red emission nebulae dominated by light from hydrogen atoms, blue
reflection nebulae produced by dust reflec |
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发帖数: 1994 | 41 Egging On the Autumnal Equinox
Credit: Phil Plait (Bad Astronomy)
Explanation: Today is the autumnal equinox -- should eggs be able to stand on end? This long-standing myth
loses much of its mystique after a demonstration that eggs can be made to stand on end during any day of the year.
Pictured above, Dr. Phil Plait (Sonoma St. U.) acting as the Bad Astronomer balanced three raw eggs on end in
late October 1998. Later, more modestly, his wife balanced five more. The li |
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发帖数: 1994 | 42 Light Can Twist as Well as Spin
Credit & Copyright: M. J. Padgett, J. Leach (U. Glasgow) et al., Royal Society
Explanation: Light is more complicated than we thought. When astronomers measure light, they are usually
concerned with its direction, energy, and spin polarization (sometimes). Recently, however, it has been more
broadly realized that photons can also have orbital angular momentum (OAM), an attribute classically analogous
to the Earth orbiting the Sun as well as spinning on |
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发帖数: 1994 | 43 Voyager at 90 AU
Illustration Credit: Walt Feimer, NASA
Explanation: Launched in 1977, Voyager 1 is now about 12 light-hours or 90 astronomical units (AU) from the
Sun, making this spacecraft humanity's most distant ambassador to the cosmos. Well beyond the orbits of the
outer planets, Voyager 1 is believed to be entering the realm of deep space near the edge of the heliosphere, the
region dominated by the solar wind and magnetic field. Causing some debate, new results fr |
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发帖数: 1994 | 44 Saturn: Lord of the Rings
Credit: Hubble Heritage Team, (AURA / STScI), R.G. French (Wellesley College), J. Cuzzi (NASA/Ames), L. Dones (SwRI), J. Lissauer (NASA/Ames)
Explanation: Born in 1564, Galileo used a telescope to explore the Solar System. In 1610, he became the first to be amazed by Saturn's rings, After nearly 400 years, Saturn's magnificent rings still offer one of the most stunning astronomical sights.
Uniquely bright compared to the rings of the other gas giants, Saturn's ring syst |
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发帖数: 166 | 45 http://skyandtelescope.com/news/article_1165_1.asp
Hubble Gets a Reprieve
By Richard Tresch Fienberg
January 29, 2004 |
The battle over the future of the Hubble Space Telescope has taken a turn
for the better, at least from the perspective of the observatory's
supporters. The conflict began on January 16th, when NASA administrator
Sean O'Keefe shocked astronomers worldwide by announcing that there will be
no more Space Shuttle missions to maintain and upgrade the orbiting telescope. |
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发帖数: 1994 | 46 NGC 613: Spiral of Dust and Stars
Credit: M. Neeser (Univ.-Sternwarte M|nchen), P. Barthel (Kapteyn Astron. Institute), H. Heyer, H. Boffin (ESO), ESO
Explanation: When morning twilight came to the Paranal Observatory in Chile, astronomers Mark Neeser and Peter Barthel interrupted their search for faint quasars, billions of light-years away. And just for a moment, they used Very Large Telescopes at
the European Southern Observatory to appreciate the beauty of the nearby Universe. One result was |
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发帖数: 667 | 47 Astronomers have discovered another TNO last year, but this time the
one they found is quite large: 1100 miles across, almost 3/4 the size of
Pluto.
It is tentatively named Sedna, the Innuit Goddess of Sea.
Sedna is currantly about 90AU away from the Sun, and in its perihelion
it might move as close as 72AU to the Sun. Its orbit, however is quite
elliptic. It is believed its aphelion can be as far as 1000AU.
Sedna is too small to be a planet. It's not a KBO, either, for it's too
far away. It cou |
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发帖数: 166 | 48 发信人: bfel (Jin), 信区: Physics
标 题: Thomas Gold: 1920--2004
发信站: Unknown Space - 未名空间 (Wed Jun 23 17:14:54 2004) WWW-POST
Thomas Gold, the controversial US-based astronomer and geoscientist, died
yesterday in Ithaca, New York, at the age of 84. Gold is best known for
developing, along with Hermann Bondi and the late Fred Hoyle, the steady-state
theory of the universe. It assumes that we live in a world that has no
beginning or end, in which matter is constantly being created. Although the
theory |
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发帖数: 1994 | 50 Moon, Mercury, Monaco
Credit & Copyright: Vincent Jacques
Explanation: Low on the western horizon after sunset, a slender
crescent Moon and wandering planet Mercury join the lights
of Menton and Monaco along the French Riviera. Astronomer
Vincent Jacques took advantage of this gorgeous photo opportunity
a week ago on March 11, when the Moon and Mercury were separated
in the sky by just three degrees. Of course, the Moon in a slender
crescent phase is always seen near the horizon, as is Mercury - |
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