Asteroid: 90 Antiope.

3488 · Mar 30, 2007

Motions of an asteroid with two whirling parts are now better known, thanks to a rare collaboration between professional and amateur astronomers. Called 90 Antiope, the asteroid consists of two egg-shaped rubble piles locked in orbit, like two twirling dancers facing one another with linked arms. Antiope is thought to be the remnants of a larger asteroid, dubbed Themis, which astronomers think was destroyed by an impact with another asteroid some 2.5 million years ago. The finding is detailed in the April 2007 issue of the scientific journal Icarus. Using the 10-meter Keck II telescope in Hawaii, astronomers discovered in 2000 that Antiope, once thought to be a typical asteroid floating between the orbits of Mars and Jupiter, actually consists of two gravitationally linked space rocks. Subsequent observations by Keck II and the Very Large Telescope in Chile determined the orbits of Antiope’s two parts, each of which were found to be about 53 miles (86 km) in diameter and separated by about 106 miles (171 km). But uncertainties remained, and in 2005 the team invited observers around the world to turn their telescopes on the asteroid pair when they were predicted to undergo a mutual eclipse and occultation. In an eclipse, one member of the duo casts a shadow over the other; in an occultation, one passes in front of the other, completely blocking its light. The open invitation paid off, and over a period of six months, professional and amateur astronomers teamed up and observed numerous eclipses and occultations by Antiope. Some of the amateur astronomers seemed absolutely tickled to share the spotlight with professionals. “What is really a thrill is to have my little 7-inch telescope with an 8-meter telescope on the same paper. It is unbelievable,” said Peter Dunckel, 75. Dunckel observed Antiope from the backyard of his vacation home in Grass Valley, California, for 35 hours over a period of six weeks.<</safety_wrapper> <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Mar 30, 2007

Sorry, image did not attach. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 5, 2007

Further info on this. 90 Antiope. BERKELEY ‹ Roping together observations from the world's largest telescopes as well as the small instrument of a local backyard amateur, astronomers have assembled the most complete picture yet of a pair of asteroids whirling around one another in a perpetual pas de deux. Artist's rendering of the binary asteroid 90 Antiope, located in the outer part of the main asteroid belt between Mars and Jupiter. Credit: Copyright European Southern Observatory In a paper to be published in the April 2007 issue of the journal Icarus, a team of University of California, Berkeley, and Paris Observatory astronomers depict the asteroid 90 Antiope as two slightly egg-shaped rubble piles locked in orbit, like two twirling dancers facing one another with linked arms. This new view of Antiope is the culmination of research that started in 2003 and that eventually included data supplied by both professional and amateur astronomers from around the globe. Before the year 2000, Antiope was just another main-belt asteroid, one of millions between the orbits of Mars and Jupiter. But that year, it was resolved into a doublet, thanks to sharper pictures obtained with adaptive optics (AO) on the largest ground-based telescope, the 10-meter Keck II telescope in Hawaii. Yet, even with AO, these two asteroids were too small for astronomers to discern their shape or to see more than two bright blobs revolving around their center of mass. Two years ago, with improved images from the European Southern Observatory's 8-meter Very Large Telescope (VLT) in Chile and Keck II, University of California, Berkeley astronomer Franck Marchis and colleagues in France were able to determine the approximate orbit of the two asteroids, each of them about 86 kilometers in diameter and separated by about 171 kilometers. But uncertainties remained, and in 2005 the team invited observers around the world to <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

JonClarke · Apr 5, 2007

Extraordinary! <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

3488 · Apr 5, 2007

Hi Jon, Could not agree with you more. It does seem that 90 Antiope is a double Type C (Carbonaceous) asteroid. Probably a larger version of 253 Mathilde, of which we got good images from the NEAR Shoemaker spacecraft on route to 433 Eros. Anyway, I think it will be time to chase up the DAWN team on the 1 Ceres & 4 Vesta orbital mission to see which other asteroids DAWN could encounter on route!!! It is rumoured that 2 Pallas could also be approached. 90 Antiope looks as if it would be worth investigatiing for a potential flyby with DAWN (postion & fuel permitting). Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

JonClarke · Apr 5, 2007

Hi Andrew Pallas would be great if Dawn could fly by. We know so little about the large asteroids. As for doubles, your picture looks like ti was done by Ron Miller. I had a book once with lots of paintings by him (and Bill Hartmann) of exotic locations in the solar system. Binary asteroids featured prominantly. Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

3488 · Apr 10, 2007

Hi Jon. I understand that 2 Pallas is an option after the 1 Ceres orbital tour. You are correct. We know precious little about the larger asteroids. 253 Mathilde is the largest that we have seen up close to date. Rosetta will rendezvous with 21 Lutetia, in July 2010, a large type M asteroid!!! Will be very interesting indeed. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

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