NEOWISE, a NASA mission that hunts for near-Earth asteroids and comets, has detected two objects heading towards Earth’s vicinity, one a comet and the other an apparent asteroid-comet hybrid.
Neither will come close enough to pose a threat to our planet.
Object C/2016 U1 NEOWISE is a long-period comet that comes from the outer solar system and takes thousands of years to complete one solar orbit.
Scientists confirm it is a comet because it is releasing gas and dust as it heads toward its closest point to the Sun, known as perihelion.
It will reach that milestone, located within Mercury’s orbit, on January 14.
Depending on its brightness, which varies, as is typical for comets, C/2016 U1 may be visible to northern hemisphere viewers with binoculars.
Astronomers are uncertain as to whether the second object, 2016 WF9, is an asteroid or comet. First observed by NEOWISE in late November, it has a solar orbit of 4.9 years which takes it from about Jupiter’s location to just within Earth’s orbit.
Estimated to have a size between 0.3 and 0.6 miles (0.5 to one km), this object is dark, reflecting only a small percentage of the sunlight that hits it.
While its orbit and reflectivity are typical for comets, 2016 WF9 does not have the cloud of gas and dust characteristic of comets.
Its orbit suggests it could have once been a comet that broke apart. It could also be an asteroid from the main belt that was once part of a group of similar dark objects but somehow separated from them.
“This object illustrates that the boundary between asteroids and comets is a blurry one; perhaps over time, this object has lost the majority of the volatiles that linger on or just under its surface,” explained James Bauer of NASA’s Jet Propulsion Laboratory (JPL).
2016 WF9 will make its closest approach to Earth on February 25, coming within almost 32 million miles of our planet.