NASA | JPL-Caltech | Universities Space Research Association | 2017 Dec 22
[img3="These radar images of near-Earth asteroid 3200 Phaethon were generated by astronomers at the National Science Foundation's Arecibo Observatory on Dec. 17, 2017. Observations of Phaethon were conducted at Arecibo from Dec.15 through 19, 2017. At time of closest approach on Dec. 16 at 3 p.m. PST (3 p.m. EST, 11 p.m. UTC) the asteroid was about 1.1 million miles (1.8 million kilometers) away, or about 4.6 times the distance from Earth to the moon. The encounter is the closest the object will come to Earth until 2093. Credit: Arecibo Observatory/NASA/NSF"]https://www.jpl.nasa.gov/spaceimages/im ... _hires.jpg[/img3][hr][/hr]After several months of downtime in the aftermath of Hurricane Maria, the Arecibo Observatory Planetary Radar returned to normal operation providing the best images to date of near-Earth asteroid 3200 Phaethon, which is thought to be the parent body for the Geminid meteor shower. The radar images, which are subtle at available resolution, reveal the asteroid is spheroidal in shape and has a large concavity at least several hundred meters in extent near the leading edge and a conspicuous dark, circular feature near one of the poles. Arecibo’s radar images of Phaethon have resolutions as fine as about 250 feet (75 meters) per pixel.
“These new observations of Phaethon show it may be similar in shape to asteroid Bennu, the target of NASA’s OSIRIS-REx spacecraft, but 10 times larger,” noted Dr. Patrick Taylor, Group Lead for Planetary Radar for Arecibo Observatory. “The dark feature could be a crater or some other topographic depression that did not reflect the radar beam back at us.”
Radar images obtained at Arecibo indicate Phaethon has a diameter of about 3.6 miles (6 kilometers) -- roughly 0.6 mile (1 kilometer) larger than previous estimates. Phaethon is the second largest near-Earth asteroid classified as "Potentially Hazardous." Near-Earth objects are classified as potentially hazardous asteroids (PHAs), based on their size and how closely their orbits approach Earth. ...
