I must confess I’ve never really considered this before and the way the press release is worded leaves me with the question: are these “contact binaries” actually two separate asteroids or are they just sort of stuck together by whatever (like gravitationally bound, impact fused etc)?
The NASA press release:
A collage of radar images of near-Earth asteroid 2006 DP14 was generated by NASA scientists using the 230-foot (70-meter) Deep Space Network antenna at Goldstone, Calif., on the night of Feb. 11, 2014.
Delay-Doppler radar imaging revealed that the asteroid is about 1,300 feet (400 meters) long, 660 feet (200 meters) wide, and shaped somewhat like a big peanut. The asteroid’s period of rotation is about six hours. The asteroid is of a type known as a “contact binary” because it has two large lobes on either end that appear to be in contact. Previous radar data from Goldstone and the Arecibo Observatory in Puerto Rico has shown that at least 10 percent of near-Earth asteroids larger than about 650 feet (200 meters) have contact binary shapes like that of 2006 DP14. The data were obtained over an interval of 2.5 hours as the asteroid completed about half a revolution. The resolution is about 60 feet (19 meters) per pixel.
The data were obtained on Feb. 11 between 9:03 a.m. and 11:27 p.m. PST (12:03 a.m. to 2:27 a.m. EST on Feb. 12). At the time of the observations, the asteroid’s distance was about 2.6 million miles (4.2 million kilometers) from Earth. That is about 11 times the average distance between Earth and its moon. The asteroid’s closest approach to Earth occurred on Feb. 10, at a distance of about 1.5 million miles (2.4 million kilometers). Continue reading →
A meteorite with about the mass of a small car impacted the moon last September and it was seen by Spanish astronomers. I don’t often mention Spanish astronomers, more the pity and bad on me. Spain has some of the best observers and astronomers as there are anywhere.
In this case on 11 September 2013, Prof. Jose M. Madiedo was operating two telescopes in the south of Spain that were searching for these impact events. At 2007 UTC he witnessed an unusually long and bright flash in Mare Nubium, an ancient lava-filled basin with a darker appearance than its surroundings.
We are hearing about this now because the scientists involved published their description of the event in the journal Monthly Notices of the Royal Astronomical Society. By the way, video links are included below the fold.
The Spanish telescopes are part of the Moon Impacts Detection and Analysis System (MIDAS) system that monitors the lunar surface. This project is being undertaken by Prof. Jose Maria Madiedo, from the University of Huelva (UHU), and by Dr. Jose L. Ortiz, from the Institute of Astrophysics of Andalusia (IAA-CSIC) and continues a pioneering program that detected sporadic lunar impact flashes for the first time.
ESA can actually keep tabs on Gaia visually. I think this is just amazing. Using the Very Large Telescope at the European Southern Observatory in Chile Gaia actually can be seen. It’s a very small satellite very far away, over a million times fainter than can be see with the human eye.
From the ESA caption:
To measure Gaia’s position in the sky, a network of small and medium telescopes are monitoring the spacecraft on a daily basis. This information is being fed into the orbit reconstruction being performed at ESA’s Space Operations Centre, yielding an accuracy of 150 m on Gaia’s position and of 2.5 mm/s on its motion.
These two images, taken about 6.5 minutes apart on 23 January, are the result of a close collaboration between ESA and the European Southern Observatory to observe Gaia.
The Hubble team have been watching hundreds of individual stars in the the Large Magellanic Cloud (LMC) over the past seven years and have mapped out their movements. What they got for their “trouble” is a precise measurement of the rotation of the galaxy! This is a first too.
The answer? The LMC rotates once every 250 million years, about the same as our solar system does in the Milky Way.