Most of us believe that the night sky is permanent and unchanging. After all, navigators have steered their ships using fixed stellar patterns for centuries, and our eyes still trace the same outlines of the same heroes and villains that star gazers have identified for millennia. But what if we haven’t been watching closely enough? What if our night sky is changing?
Across the Milky Way, there are vacant spaces where a star once brightly shone. Some left clues in a dramatic death or faded into retirement. Others moved into a new neighbourhood. The search is an ongoing one for lead scientist Beatriz Villarroel and her colleagues, one that started several years ago as part of a hunt for potential signs of alien intelligence.
One hundred mysterious red objects in the sky have disappeared inexplicably over the last 70 years. One possible explanation for their disappearance is alien technology. The international team of scientists led by Villarroel identified about 100 objects that vanished in short periods, some of them rapidly growing several thousand times brighter before they disappeared.
The scientists working on the project called “Vanishing & Appearing Sources during a Century of Observations” (VASCO) have noticed the surprising disappearance of stars. Although the concrete reason behind their absence from the night sky is yet to be discovered, scientists presume that it could be due to new astrophysical phenomena or extra-terrestrial activity.
The vanished light sources could represent short-lived flashes in the night or, possibly, the disappearance of a lasting heavenly body if scientists can indeed confirm what they’re seeing. The study authors stress that while their preliminary findings almost certainly represent natural and well-understood events, they hope that future results will be relevant to astronomy and the search for extraterrestrial intelligence (SETI).
According to Villarroel, when stars die, they tend to explode in a burst of glory that’s hard to miss—Chinese astronomers documented the first supernova more than 1,800 years ago. But a star or galaxy melting quietly into the night would demand more explanation.
Such a find could indicate an unexpected way for stars to die, or perhaps an advanced civilisation blocking their sun with solar panels. Either would mark an exciting discovery.
The team of around 20 astronomers and astrophysicists made an effort to compare a series of sky images taken by the US Naval Observatory (USNO) for decades starting in 1949, with observations by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) between 2010 and 2014.
The team used software to analyse the 600 million light sources that should have appeared in both datasets and came up with about 150,000 candidates that appeared to have winked out. They cross-referenced those missing lights with images from other datasets to isolate the especially promising possibilities. Lastly, they scrutinised the remaining 24,000 candidates, one by one, to see which represented real points of light as opposed to camera malfunctions or similar accidents. In the end, they found about 100 sources that truly appeared to have vanished.