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Asteroid 2008 BT18 is gliding past Earth this weekend and astronomers have just discovered that it is a binary system. "The sizes of the two components are 600 m for the primary and >200 m for the secondary," says Lance Benner of JPL. "The primary looks spheroidal, but we don't yet know about the shape of the secondary." Benner and others using a giant radar in Arecibo, Puerto Rico, obtained this "delay-doppler" image of the pair on July 7th:
Asteroids often come in pairs, with the two objects spinning around each other. Now scientists say sunlight could be the cause of these binary boulders.
A new study suggests energy from the sun can spin up a single asteroid until it ejects material that becomes a separate satellite.
Astronomers first discovered these strange asteroid pairs 15 years ago, and have been puzzled about what causes them. Now scientists have created a computer model that matches what they see.
"So far our results match the properties of binary asteroids quite well," said astronomer Kevin Walsh of the Observatoire de la Cote D'Azur in Nice, France. Walsh led the study when he was a graduate student at the University of Maryland, working with his advisor Derek Richardson and Patrick Michel of the Cassiope'e, University of Nice-Sophia Antipolis, in Nice.
A new study suggests energy from the sun can spin up a single asteroid until it ejects material that becomes a separate satellite.
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| ©diagram - Minor Planet Center; image - NASA/Johns Hopkins University Applied Physics Laboratory |
| The main belt is between the orbits of Mars and Jupiter, and contains countless asteroids. |
Astronomers first discovered these strange asteroid pairs 15 years ago, and have been puzzled about what causes them. Now scientists have created a computer model that matches what they see.
"So far our results match the properties of binary asteroids quite well," said astronomer Kevin Walsh of the Observatoire de la Cote D'Azur in Nice, France. Walsh led the study when he was a graduate student at the University of Maryland, working with his advisor Derek Richardson and Patrick Michel of the Cassiope'e, University of Nice-Sophia Antipolis, in Nice.
In the late 19th century Gregor Mendel used peas to show that one copy of a gene (allele) is inherited from the mother and one from the father. In the progeny, the inherited genes are expressed at the right time and in the right place, but until recently, it was thought that although gene products could be modified during the life of the organism, the genes themselves were unchanged, except for random mutation.
Headlines around the world hailed the fossils as "Lucy's Child" and "Lucy's Daughter" when anthropologists first reported finding the skull and bones of a 3-year-old girl who lived and died more than 3.3 million years ago in what is now Ethiopia's Afar Desert.
"But she lived at least 150,000 years before Lucy was ever born, so that little girl couldn't ever have been any child of Lucy," said anthropologist Zeresenay Alemseged with a laugh.
"Yet she certainly belonged to Lucy's lineage - and they both lived in what we can now call the cradle of mankind."
"But she lived at least 150,000 years before Lucy was ever born, so that little girl couldn't ever have been any child of Lucy," said anthropologist Zeresenay Alemseged with a laugh.
"Yet she certainly belonged to Lucy's lineage - and they both lived in what we can now call the cradle of mankind."
The FBI keeps information on 'Escalante Man' discovery from Utah archaeologists, treat the site as a crime scene
An aging American Indian with rotting teeth and arthritic joints sat down and died in the Utah desert outside Escalante with a musket, ammunition and a bucket. Blowing sand covered his corpse for more than a century before a hiker stumbled across it last year.
This is the likely scenario of how a nearly complete skeleton, dubbed "Escalante Man" in BLM documents, came to be buried a few hundred paces off Highway 12 in the Grand Staircase-Escalante National Monument. What remains a mystery is why a dozen FBI agents excluded archaeologists from its April 16 excavation, treating the site as a crime scene rather than the historic site many believe it clearly was. "It's an ongoing investigation. Our policy is we cannot comment on it," FBI spokesman Juan Becerra said. Agents stress they had legitimate reasons for excluding the monument's own archaeologist from the dig, even though they invited a TV news crew to document it, and the U.S. Attorney's Office signed off on the investigation. While the BLM and FBI acted in partnership on the dig, the episode has attracted criticism from state officials charged with protecting cultural resources and triggered dissension within the BLM.
An aging American Indian with rotting teeth and arthritic joints sat down and died in the Utah desert outside Escalante with a musket, ammunition and a bucket. Blowing sand covered his corpse for more than a century before a hiker stumbled across it last year.
This is the likely scenario of how a nearly complete skeleton, dubbed "Escalante Man" in BLM documents, came to be buried a few hundred paces off Highway 12 in the Grand Staircase-Escalante National Monument. What remains a mystery is why a dozen FBI agents excluded archaeologists from its April 16 excavation, treating the site as a crime scene rather than the historic site many believe it clearly was. "It's an ongoing investigation. Our policy is we cannot comment on it," FBI spokesman Juan Becerra said. Agents stress they had legitimate reasons for excluding the monument's own archaeologist from the dig, even though they invited a TV news crew to document it, and the U.S. Attorney's Office signed off on the investigation. While the BLM and FBI acted in partnership on the dig, the episode has attracted criticism from state officials charged with protecting cultural resources and triggered dissension within the BLM.
When engineers flick the switch to turn on the world's fastest supercomputer later this year it will be capable of chewing its way through 1,000 trillion calculations every second.
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| ©SLP |
| Inside the hard drive. |
Scientists funded by the Air Force Office of Scientific Research have used a single photon technique to observe the evolution of individual electron spins in semiconductor nanostructures.
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| ©SPL |
| Spintronics harnesses the spin of sub-atomic particles. |
Two Russian astronauts aboard the International Space Station have made a daring spacewalk to repair their Soyuz descent capsule, Russian mission control said on Friday.
Sergei Volkov and Oleg Kononenko managed to remove an explosive bolt from the capsule, one of 10 used to separate two parts of the module during reentry, fixing a problem that had led to rough landings for two previous crews.
Sergei Volkov and Oleg Kononenko managed to remove an explosive bolt from the capsule, one of 10 used to separate two parts of the module during reentry, fixing a problem that had led to rough landings for two previous crews.
When observing with the GEMINI telescopes, two astronomers from Brazil and the United States discovered for the first time asteroids that are similar to "ordinary chondrites", the most common meteorites found on Earth. Until now, astronomers have failed to identify their asteroidal sources because of the various geologic processes that occur after the meteorites are ejected from their asteroidal parent body. This discovery is being published this week in Astronomy & Astrophysics.
Astronomy & Astrophysics is publishing the first discovery by T. Mothé-Diniz (Brazil) and D. Nesvorný (USA) of asteroids with a spectrum similar to that of ordinary chondrites, the meteoritic material that most resembles the composition of our Sun. Most of the meteorites that we collect on Earth come from the main belt of asteroids located between Mars and Jupiter [1]. They were ejected from their asteroidal "parent body" after a collision, were injected into a new orbit, and they finally felt onto the Earth. Meteorites are a major tool for knowing the history of the solar system because their composition is a record of past geologic processes that occurred while they were still incorporated in the parent asteroid. One fundamental difficulty is that we do not know exactly where the majority of meteorite specimens come from within the asteroidal main belt. For many years, astronomers failed to discover the parent body of the most common meteorites, the ordinary chondrites that represent 75% of all the collected meteorites.
Astronomy & Astrophysics is publishing the first discovery by T. Mothé-Diniz (Brazil) and D. Nesvorný (USA) of asteroids with a spectrum similar to that of ordinary chondrites, the meteoritic material that most resembles the composition of our Sun. Most of the meteorites that we collect on Earth come from the main belt of asteroids located between Mars and Jupiter [1]. They were ejected from their asteroidal "parent body" after a collision, were injected into a new orbit, and they finally felt onto the Earth. Meteorites are a major tool for knowing the history of the solar system because their composition is a record of past geologic processes that occurred while they were still incorporated in the parent asteroid. One fundamental difficulty is that we do not know exactly where the majority of meteorite specimens come from within the asteroidal main belt. For many years, astronomers failed to discover the parent body of the most common meteorites, the ordinary chondrites that represent 75% of all the collected meteorites.
Macedonian archaeologists say they have discovered a well-preserved statue of the goddess of love in the ruins of an ancient Roman city near Skopje, Macedonia.
