The six red dots in this composite picture indicate the location of the first new near-Earth asteroid seen by NASA's Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) since the spacecraft came out of hibernation in December 2013. The asteroid, called 2013 YP139, is the first of hundreds of space-rock discoveries expected during its renewed mission. The inset shows a zoomed-in view of one of the detections of 2013 YP139.
2013 YP139 was discovered by NEOWISE on Dec. 29, 2013. The mission's sophisticated software picked out the moving object against a background of stationary stars.
Near-Earth objects are asteroids and comets with orbits that come close to Earth's path around the sun. 2013 YP139, is currently about 27 million miles (43 million kilometers) from Earth. Based on its infrared brightness, scientists estimate it to be approximately 0.4 miles (650 meters) in diameter and extremely dark. Because NEOWISE is an infrared telescope, it senses heat from asteroids. 2013 YP139 is as dark as a piece of coal, and it glows brightly at infrared wavelengths. The shortest infrared wavelength, 3.4 microns, is color-coded blue, and the longer wavelength, 4.6 microns, is color-coded red. The asteroid appears as a string of red dots because it is much cooler than the stars. Stars are thousands of degrees, but the asteroid is close to room temperature, so it is red in these images.
While asteroid 2013 YP139 orbits the sun in an elliptical orbit nearly in the plane of our solar system and is classified as a potentially hazardous asteroid, it is not likely to approach within Earth's vicinity anytime over the next 100 years. However, the asteroid's future motion can bring it within about 300,000 miles (490,000 kilometers) of Earth's orbit, so its long-term motion will be closely monitored.
The image is about 1.5 degrees across. Asteroid 2013 YP139 was traveling across the sky at about 3.2 degrees per day when these images were taken. For reference, the full moon is about 0.5 degree across.
NEOWISE originated as a mission called WISE, which was put into hibernation in 2011 upon completing its goal of surveying the entire sky in infrared light. WISE cataloged three quarters of a billion objects, including asteroids, stars and galaxies. In August 2013, NASA decided to reinstate the spacecraft on a mission to find and characterize more asteroids.
JPL manages NEOWISE for NASA's Science Mission Directorate at the agency's headquarters in Washington. The Space Dynamics Laboratory in Logan, Utah, built the science instrument. Ball Aerospace & Technologies Corp. of Boulder, Colo., built the spacecraft. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.