[meteorite-list] Halloween Skies to Include Dead Comet Flyby (2015 TB145)
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 30 Oct 2015 23:31:03 -0700 (PDT)
Halloween Skies to Include Dead Comet Flyby
Jet Propulsion Laboratory
October 30, 2015
This image of asteroid 2015 TB145, a dead comet, was generated using radar
data collected by the National Science Foundation's 1,000-foot (305-meter)
Arecibo Observatory in Puerto Rico. The radar image was taken on Oct.
30, 2015, and the image resolution is 25 feet (7.5 meters) per pixel.
Image credit: NAIC-Arecibo/NSF
The large space rock that will zip past Earth this Halloween is most likely
a dead comet that, fittingly, bears an eerie resemblance to a skull.
Scientists observing asteroid 2015 TB145 with NASA's Infrared Telescope
Facility (IRTF) on Mauna Kea, Hawaii, have determined that the celestial
object is more than likely a dead comet that has shed its volatiles after
numerous passes around the sun.
The belated comet has also been observed by optical and radar observatories
around the world, providing even more data, including our first close-up
views of its surface. Asteroid 2015 TB145 will safely fly by our planet
at just under 1.3 lunar distances, or about 302,000 miles (486,000 kilometers),
on Halloween (Oct. 31) at 1 p.m. EDT (10 a.m. PDT, 17:00 UTC).
The first radar images of the dead comet were generated by the National
Science Foundation's 305-meter (1,000-foot) Arecibo Observatory in Puerto
Rico. The radar images from Arecibo indicate the object is spherical in
shape and approximately 2,000 feet (600 meters) in diameter and completes
a rotation about once every five hours.
"The IRTF data may indicate that the object might be a dead comet, but
in the Arecibo images it appears to have donned a skull costume for its
Halloween flyby," said Kelly Fast, IRTF program scientist at NASA Headquarters
and acting program manager for NASA's NEO Observations Program.
Managed by the University of Hawaii for NASA, the IRTF's 3-meter (10 foot)
telescope collected infrared data on the object. The data may finally
put to rest the debate over whether 2015 TB145, with its unusual orbit,
is an asteroid or is of cometary origin.
"We found that the object reflects about six percent of the light it receives
from the sun," said Vishnu Reddy, a research scientist at the Planetary
Science Institute, Tucson, Arizona. "That is similar to fresh asphalt,
and while here on Earth we think that is pretty dark, it is brighter than
a typical comet which reflects only 3 to 5 percent of the light. That
suggests it could be cometary in origin -- but as there is no coma evident,
the conclusion is it is a dead comet."
Radar images generated by the Arecibo team are available at:
Asteroid 2015 TB145 was discovered on Oct. 10, 2015, by the University
of Hawaii's Pan-STARRS-1 (Panoramic Survey Telescope and Rapid Response
System) on Haleakala, Maui, part of the NASA-funded Near-Earth Object
Observations (NEOO) Program. The next time the asteroid will be in Earth's
neighborhood will be in September 2018, when it will make a distant pass
at about 24 million miles (38 million kilometers), or about a quarter
the distance between Earth and the sun.
Radar is a powerful technique for studying an asteroid's size, shape,
rotation, surface features and surface roughness, and for improving the
calculation of asteroid orbits. Radar measurements of asteroid distances
and velocities often enable computation of asteroid orbits much further
into the future than would be possible otherwise.
NASA places a high priority on tracking asteroids and protecting our home
planet from them. In fact, the U.S. has the most robust and productive
survey and detection program for discovering near-Earth objects (NEOs).
To date, U.S.-funded assets have discovered over 98 percent of the known
In addition to the resources NASA puts into understanding asteroids, it
also partners with other U.S. government agencies, university-based astronomers,
and space science institutes across the country, often with grants, interagency
transfers and other contracts from NASA, and also with international space
agencies and institutions that are working to track and better understand
these objects. In addition, NASA values the work of numerous highly skilled
amateur astronomers, whose accurate observational data helps improve asteroid
orbits after they are found.
NASA's Jet Propulsion Laboratory, Pasadena, California, hosts the Center
for Near-Earth Object Studies for NASA's Near-Earth Object Observations
Program within the agency's Science Mission Directorate.
More information about asteroids and near-Earth objects is at these websites:
Jet Propulsion Laboratory, Pasadena, Calif.
agle at jpl.nasa.gov
Received on Sat 31 Oct 2015 02:31:03 AM PDT