| Ultimi arrivi - Asteroids and Comets |
Comets-Schwassmann_Wachmann_1-07.jpgComet Schwassmann-Wachmann 3: the whole "crumbling" Comet (1)53 visiteThis false-color mosaic of crumbling Comet Schwassmann-Wachmann 3 spans about 6° (about 12 full moons) along the Comet's orbit. Recorded on May 4-6, 2006, by an infrared camera on board the Spitzer Space Telescope, the picture captures about 45 of the 60 or more alphabetically cataloged large Comet Fragments. The brightest fragment at the upper right of the track is Fragment "C" (frame 1). Bright Fragment "B" is below and left of center (frame 2). Looking for clues to how the Comet broke up, Spitzer's infrared view also captures the trail of dust left over as the Comet deteriorated during previous passes. Emission from the dust particles warmed by sunlight appears to fill the space along the cometary orbit. The fragments are near their closest approach in the coming days, about 10 MKM away, and none pose any danger to our fair Planet.%13 %335 %2006
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Comets-Schwassmann_Wachmann_1-06.jpgComet Schwassmann-Wachmann 3 and M 5754 visiteMoving rapidly through planet Earth's night sky, Fragment "C" of crumbling comet 73P/Schwassmann-Wachmann 3 passed almost directly in front of M 57 - the "Ring Nebula" - and faint spiral galaxy IC 1296 on May 8, 2006. In fact, in this gorgeous view, the bright head of mentioned Fragment "C" is separated by only about 0,1° from M 57, with the tail apparently engulfing nebula and galaxy.
Recorded from Elizabeth, Illinois, USA, this picture corresponds to the cosmic scene only 30 minutes after yesterday's picture of the approaching alignment. The relative motion of the comet against the background stars and nebulae is easy to see when comparing the two images. This comet's fragments will be near their closest approach in the coming days, about 10 MKM away, and none pose any danger to our fair planet.%12 %396 %2006
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Comets-Schwassmann_Wachmann_1-05.jpgComet Schwassmann-Wachmann 3, M 57 and IC 129660 visiteAs dawn approached on May 8, 2006, astronomer Stefan Seip carefully watched Fragment "C" of broken Comet 73P/Schwassmann-Wachmann 3 approach M 57 - the Ring Nebula, and faint spiral galaxy IC 1296.
Of course, even though the trio seemed to come close together in a truly cosmic photo opportunity, the comet is in the inner part of our Solar System, a mere 0,5 Light-Minutes (LM) or so from Seip's telescope located near Stuttgart, Germany, planet Earth.
The Ring Nebula (upper right) is more like 2000 LY distant, well within our own Milky Way Galaxy. At a distance of 200 MLY, IC 1296 (between the Comet and the Ring Nebula) is beyond even the Milky Way's boundaries. Because the Comet is so close, it appears to move relatively rapidly against the distant stars. This dramatic telescopic view was composited from two sets of images; one compensating for the Comet's apparent motion and one recording the background stars and nebulae.%11 %472 %2006
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Comets-Schwassmann_Wachmann_1-04.jpgComet Schwassmann-Wachmann 3 from SST53 visiteThis image from NASA's Spitzer Space Telescope (SST) shows three of the many fragments making up Comet 73P/Schwassman-Wachmann 3. The infrared picture also provides the best look yet at the crumbling comet's trail of debris, seen here as a bridge connecting the larger fragments.
The comet circles around our Sun every 5,4 years.
In 1995, it splintered apart into four pieces, labeled "A" through "D", with "C" being the biggest. Since then, the comet has continued to fracture into dozens of additional pieces. This image is centered about midway between fragments "C" and "B"; fragment "G" can be seen in the upper right corner.
The comet's trail is made of dust, pebbles and rocks left in the comet's wake during its numerous journeys around the sun. Such debris can become the stuff of spectacular meteor showers on Earth.
This image was taken on April 1, 2006, by Spitzer's Multi-Band Imaging Photometer using the 24-micron wavelength channel.%07 %321 %2006
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Comets-Schwassmann_Wachmann_1-03.jpgComet Schwassmann-Wachmann 3: fragment "B"52 visitePeriodic comet 73P/Schwassmann-Wachmann 3 has fallen apart before. A cosmic souffle of ice and dust left over from the early Solar System, this comet was seen to split into several large pieces during the close-in part of its orbit in 1995. However, this time the comet seems to be rapidly disintegrating with over 3 dozen fragments, named alphabetically, now stretching several degrees across the sky. Since comets are relatively fragile, stresses from heat and gravity and outgassing, for example, could be responsible for their tendency to breakup in such a spectacular fashion. On April 18th, 2006, HST recorded this sharp view of prolific Fragment B, itself trailing dozens of smaller pieces, each with its own cometary coma and tail. The picture spans over 3000 Km at the comet's April 18 distance of 32 MKM from planet Earth. With its brightest fragment presently too faint to be seen with the naked eye, comet Schwassmann-Wachmann 3 will pass closest to Earth on May 13 at a distance of about 11 MKM.%04 %280 %2006
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Comets-Schwassmann_Wachmann_1-02.jpgComet Schwassmann-Wachmann 3 from HST52 visiteHubble Space Telescope is providing astronomers with extraordinary views of Comet 73P/Schwassmann-Wachmann 3. The fragile comet is rapidly disintegrating as it approaches the Sun. Hubble images have uncovered many more fragments than have been reported by ground-based observers. These observations provide an unprecedented opportunity to study the demise of a comet nucleus. The comet is currently a chain of over three dozen separate fragments, named alphabetically, stretching across the sky by several times the angular diameter of the Moon. Hubble caught two of the fragments (B and G) shortly after large outbursts in activity.
HST shows several dozen of "mini-comets" trailing behind each main fragment and probably associated with the ejection of house-sized chunks of surface material.%29 %643 %2006
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Tempel1-ZZ-ZL-PIA02132_fig1.jpgThe "Sunny Side" of Comet Tempel-153 visiteCaption originale:"This image composite shows comet Tempel 1 in visible (left) and infrared (right) light. The infrared picture highlights the warm, or sunlit, side of the comet, exactly where NASA's Deep Impact probe hit. These data were acquired about six minutes before impact.
The visible image was taken by the medium-resolution camera on the mission's flyby spacecraft, and the infrared data were acquired by the flyby craft's infrared spectrometer".%29 %630 %2006
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Comets-Schwassmann_Wachmann_1-01.jpgComet Schwassmann-Wachmann 3: incoming Space debris!52 visiteDa "NASA - Picture of the Day" del 26 Aprile 2006:"A crumbling comet will soon pass near the Earth. Comet 73P/Schwassmann-Wachmann 3 is brightening and may even be visible to the unaided eye when the fragmented comet zooms past Earth during the middle of next month. Still, the small comet poses no Earth hazard, since it will pass the Earth at about 25 times the distance of the Moon. Exactly how bright Comet Schwassman-Wachmann 3 will get is unknown. It is even possible, althought unlikely, that debris from the comet will have spread out enough to cause a notable meteor shower. Pictured above, Fragment B of Comet Schwassman-Wachmann 3 was photographed two nights ago by a 8.2-meter Very Large Telescope in Chile. Visible to the lower right of the large B Fragment are many mini-comets that have broken off and now orbit the Sun separately. Each mini-comet itself sheds gas and dust and so appears to have its own hazy coma.
The comet will pass closest to the Sun on June 7, 2006".%26 %221 %2006
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Dactyl.JPGDactyl55 visitenessun commento%18 %643 %2006
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Shoemaker-Levy 9-2.jpgShoemaker-Levy 9: the W-impact (2)54 visiteThese four images of Jupiter and the luminous night-side impact of fragment W of Comet Shoemaker-Levy 9 are different versions of an average of 8 images taken by the Galileo spacecraft of July 22, 1994.
The frames that were averaged span about 30" near 8:06 UT.
These four "averaged" images show the scene without and with (top and bottom) spatial filtering and contrast enhancement, and without and with (left and right) a latitude/longitude grid. Grid spacing is 30 degrees, with 230° Longitude centered. The terminator is at about 265°. The impact location is about 43° South, as predicted, and at 280° Longitude. The dark spots to the right of the flash are from previous impacts.%18 %642 %2006
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Shoemaker-Levy 9-1.jpgShoemaker-Levy 9: the W-impact (1)54 visiteThese four pictures, taken 2,3" apart, show the early meteor, or "bolide", stage of the impact of the last major fragment of Comet Shoemaker-Levy 9 into Jupiter's night side. In the first image (8:06:12 UTC), no impact is visible. In the second picture, a bright point of light appears superimposed on the dark side of Jupiter's Southern Hemisphere. In the third image, the impact has grown so bright that it saturates the CCD picture element at the center of the image of the impact flash. By remarkable coincidence, the HST took a picture of the W-impact, also in green light, within 1" of this image, providing a complementary view of very faint associated phenomena at very high altitudes in Jupiter's atmosphere, just above the planet's edge as seen from Earth. In the final Galileo image (8:06:19 UTC), the impact flash has faded appreciably.
These images are pictures 5 through 8 of a series of 56 placed on a single frame in time-lapse fashion. We interpret the rapid rise and fall of this initial peak over just 7 seconds to be the bolide phase of the W fragment's impact, analogous to the flash of light of meteors entering Earth's atmosphere. Images immediately following this show that the luminosity continues to fade over the next 15 seconds.%18 %640 %2006
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Xena.jpgXena: another "Tenth Planet"? (2003 UB313)55 visiteNASA's Hubble Space Telescope has resolved the Tenth Planet, now nicknamed Xena, for the first time and has found that it is only just a little larger than Pluto.
Though previous ground-based observations suggested that Xena was about 30% greater in diameter than Pluto, Hubble observations taken on Dec. 9 and 10, 2005, yield a diameter of 1.490 miles (with an uncertainty of 60 miles) for Xena. Pluto's diameter, as measured by Hubble, is 1.422 miles. Xena is the large object at the bottom of this artist's concept. A portion of its surface is lit by the Sun, located in the upper left corner of the image. Xena's companion, Gabrielle, is located just above and to the left of Xena.%12 %411 %2006
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