Unexplained increase in comet activity near Earth
NASA has revealed a terrifying animation of a swarm of comets and asteroids circling our planet.
The pictures come from the space agency's asteroid hunting mission, the Near-Earth Object Wide-field Infrared Survey Explorer, or Neowise for short.
NASA issued the chilling warning that 10 new "potentially hazardous" asteroids have been discovered in the past year, along with 96 other newly spotted space rocks in our midst.
Scientists who have been analysing the data said they have seen an unexplained increase in comet activity, too.
The risk is growing that Earth will be hit by an asteroid from a meteor stream known as the Taurids, according to astronomers from the Czech Academy of Science.
They have detected a new branch with at least two asteroids measuring 200-300m in diameter.
"Most probably, the branch also includes many undetected asteroids which are dozens of metres in diameter or larger," the Czech Academy said in a press release.
"Hence, the danger of a crash with an asteroid grows markedly once every few years that the Earth encounters this stream of interplanetary material."
The new branch moves together around the sun, and the Earth encounters it once every few years for a period of about three weeks.
"During this period, the probability of a collision with a larger object (of about dozens of metres in diameter) is markedly higher," the Academy said.
The asteroids are very fragile, but when they are this large they may penetrate deep into the atmosphere and pose a real threat of collision with Earth.
Near-Earth objects (NEOs) are comets and asteroids that have been nudged by the gravitational attraction of the planets in our solar system into orbits that allow them to enter Earth's neighbourhood.
Ten of the objects discovered by Nasa's Neowise in the past year have been classified as potentially hazardous asteroids, based on their size and their orbits.
It's found 693 NEOs since the mission was restarted in December 2013. Of these, 114 are new.
"Neowise is not only discovering previously uncharted asteroids and comets, but it is providing excellent data on many of those already in the catalogue," said Amy Mainzer, Neowise principal investigator from Nasa's Jet Propulsion Laboratory in Pasadena, California.
"It is also proving to be an invaluable tool in the refining and perfecting of techniques for NEO discovery and characterisation by a space-based infra-red observatory."
There are several known asteroids that pose a risk.
The Shard-sized 2015 BN509 which flew past Earth in February could return with a vengeance, scientists have warned.
NASA and the European Space Agency want to ram into an asteroid in a bid to save humanity from a Deep Impact-style catastrophe.
They want to see whether it's possible to deflect a space rock from its course as part of a planetary defence mission.