In our never-ending search for aliens, astronomers say that vanishing stars could be a sign that they exist.
In 1950, astronomers at the US Navel Observatory pointed a telescope in the direction of the constellation 'Lupus' and took a picture.
But when scientists looked at the same patch of sky decades later, something was missing.
In 2016, researchers at Uppsala University in Sweden found that one of the Suns that was visible in the image could no longer be seen.
Advert
Years later, we still don't know what happened to the Sun - which is a star, FYI - but, by comparing old and new observations of various galaxies, the 'Vanishing & Appearing Sources during a Century of Observations' (Vasco) project say they've found a hundred more missing stars just like it.
The vanishing stars should be impossible as for thousands of years, astronomers accepted the idea that they were fixed and unchanging.
Even as we came to understand that the 'lights in the sky' were physical objects like the Sun, major changes have always been thought to happen very slowly over millions or even billions of years.
Advert
So, how did these stars suddenly disappear?
Astronomers think it could be down to extraterrestrial intelligence (SETI), as anything so unexplainable could only be due to life far more intelligent than us.
"Unless a star directly collapses into a black hole, there is no known physical process by which it could physically vanish," Dr Beatriz Villarroel of Stockholm University and Spain's Instituto de Astrofísica de Canarias explains in a new study.
"The implications of finding such objects extend from traditional astrophysics fields to the more exotic searches for evidence of technologically advanced civilizations."
Advert
The Vasco project team believes identifying vanishing stars could be useful in the search for extraterrestrial intelligence by identifying 'hot spots' in space where unexpectedly large numbers of stars are thought to have gone missing.
"Zooming in on the [hot spots] in our SETI [or technosignature] searches, we can identify the most probable locations to host extra-terrestrial intelligence," they say.
The idea behind it is a bit far-fetched but would technically provide an explanation for the vanishing stars.
Advert
Essentially, a very advanced alien civilization may be able to build a hypothetical megastructure called a Dyson sphere, which completely encompasses a star to capture its energy for the civilisation's use.
However, the hundred or so stars that have been reported as vanishing don't appear to host alien life, for now at least.
Bec Oakes