Nasa's Neowise mission discovers a comet that may be visible from the first week of 2017

Nasa's Neowise mission has discovered two new objects. One is a comet that is likely to be visible over the first week of 2017, and the other is a mysterious object that appears to straddle the line between being a comet and an asteroid. None of the newly discovered objects are considered a threat to the Earth.The comet has started emitting a plume of dust and water as it approaches the sun. The comet is likely to be visible from the Earth with a pair of binoculars, but the Nasa scientists cannot be sure because the brightness of a comet is notoriously hard to estimate. The object is designated as the C/2016 U1 NEOWISE and is in an extremely elliptical orbit around the sun. The comet will slingshot around the Sun on 14 January, and not revisit the Earth for thousands of years.The other object discovered by Neowise is the 2016 WF9. It is a mysterious object that does not appear to have a typical tail of a comet. Scientists speculate that over many orbits, the comet has lost all the matter, with only a rocky core left behind. Alternatively, the object could also have escaped from the asteroid belt. 2016 WF9 takes a scenic route across the solar system, crossing the orbits of Jupiter, the asteroid belt, Mars and Earth.Deputy Principal Investigator James "Gerbs" Bauer at JPL said "2016 WF9 could have cometary origins. 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."The Neowise mission spots comets and asteroids, and is particularly useful for finding potentially hazardous asteroids, to identify any potential threat to Earth long before an impact event occurs.