Is Earth under attack from an invisible star?

In what sounds like a chilling script of a Hollywood science fiction, scientists have claimed that an invisible star, five times the size of Jupiter, might be lurking near our solar system, occasionally kicking deadly comets towards the Earth.

According to scientists of the National Aeronautics and Space Administration, the brown dwarf star is up to five times the size of Jupiter and could be responsible for mass extinctions that occur on Earth every 26 million years.

They believe, the star nicknamed Nemesis or 'The Death Star' could be hidden beyond the edge of our solar system and only emits infrared light.

It is believed to orbit our solar system at 25,000 times the distance of the Earth to the Sun, The Sun quoted the scientists as saying.

According to them, as the star spins through the galaxy, its gravitational pull drags icy bodies out of the Oort Cloud -- a vast sphere of rock and dust twice as far away as Nemesis.

"These 'snowballs' are thrown towards Earth as comets, causing devastation similar to the asteroid that wiped out the dinosaurs 65 million years ago," the report said.

Professor John Matese, of the University of Louisiana at Lafayette, said most comets come from the same part of the Oort Cloud.

"There is statistically significant evidence that this concentration of comets could be caused by a companion to the Sun."

Now, NASA scientists believe they will be able to find Nemesis using a new heat-seeking telescope that began scanning the skies in January.

The Wide-Field Infrared Survey Explorer -- expected to find a thousand brown dwarf stars within 25 light years of the Sun -- has already sent back a photo of a comet possibly dislodged from the Oort Cloud.

Scientists' first clue to the existence of Nemesis was the bizarre orbit of a dwarf planet called Sedna.

Scientists believe its unusual, 12,000-year-long oval orbit could be explained by a massive celestial body.

Mike Brown, who discovered Sedna in 2003, said: "Sedna is a very odd object -- it shouldn't be there.

"The only way to get on an eccentric orbit is to have some giant body kick you -- so what is out there?"