Explore some of the most baffling mysteries that still remain unsolved.

Bizarre unsolved mysteries that still need answers

There’s something odd happening in our skies. Almost 100 stars seem to be missing.

They haven’t gone nova. Nor have they become black holes. With no natural explanation available, some astronomers are seeing aliens.

In 2015, a group of citizen astronomers brought the world’s attention to KIC 8462852, which quickly became known as Tabby’s Star. It was flickering. Erratically. Dramatically.

It’s no longer alone.

Some 21 other stars have been found behaving in the same seemingly unnatural way.

But, in 2016, Swedish astronomers noticed nothing.

It was nothing where something was supposed to be.

A star had vanished.

Without a trace.

Three years later, they’ve discovered at least 100 more are missing.

“Unless a star collapses directly into a black hole, there is no known physical process by which it could physically vanish,” the study reads.

“If such examples exist, this makes it interesting for searches for new exotic phenomena or even signs of technologically advanced civilisations.”

WHO TURNED OUT THE LIGHTS?

The Stockholm University and the Institute of Astrophysics of Canarias have been following-up their 2016 nothingness in space.

Back then they were comparing a 1950s photo of the constellation Lupus the Wolf to a more contemporary image. The 1950s image showed a star. The new one did not.

But there was no plume of a supernova. No sign of a collapsing, cooling husk.

This wasn’t supposed to be possible.

But this particular impossible is becoming increasingly common.

They published their findings and resolved to get to the bottom of the matter.

Four years later, they are even more confused.

The Vanishing & Appearing Sources during a Century of Observations (VASCO) project was begun in 2017 to scour space for these strange stars. It compared the recent Pan-STARRS sky survey to celestial maps and images made during the past 100 years.

Their follow-up study has just been published in the Astronomical Journal.

In total there were 600 million objects identified.

The researchers found 151,193 anomalies.

So far, only 23,667 of these have been examined.

Most were simply distortions such as lens smudges or passing insects. Others were asteroids or fast-moving stars.

But 100 cannot yet be explained.

“The implications of finding such objects extend from traditional astrophysics fields to the more exotic searches for evidence of technologically advanced civilisations,” the researchers wrote.

RED TRANSIENTS

The VASCO astronomers are asking: Are these even stars?

Initially, they look like dim red dots in the darkness of space.

Then they start to get brighter. Much brighter. Some peak at several thousand times brighter.

Then they blink off.

Stars don’t just vanish.

They do, however, burn out. And even then they don’t go meekly into the night. They can slowly burn down to the level of a white dwarf star. They can go out with a bang as a supernova. Or they could collapse inward and become a black hole.

But no white dwarfs can be seen where the red stars once were.

There’s no obvious sign of nova.

And black hole collapses are supposed to be exceedingly rare.

“We are very excited about following up on the 100 red transients we have found,” project leader Beatriz Villarroel said.

“But we are clear that none of these events have shown any direct signs of being ETI,” adds study co-author Martin López Corredoira.

“We believe that they are natural, if somewhat extreme, astrophysical sources.”

HERE BE ALIENS?

It’s possible that these flashes are massive solar flares blasted outward from otherwise dim red dwarf stars.

Most likely they’re some cosmological processes we’re yet to understand.

But being evidence of extraterrestrials is by far the most enticing – if most unlikely – idea.

The research paper speculates the bright red “stars” may, in fact, be immensely powerful lasers. These could be used to propel light-sail craft between the stars or for interstellar morse-code communications.

And then there’s the Dyson sphere idea – where entire stars are encapsulated in a sphere of solar panels to soak up every last erg of their energy.

Could complete examples of these megastructure engineering projects sometimes suddenly flare to dump excess heat into the vastness of space?

These are just ideas.

VASCO’s researchers hope to establish a new citizen science project and apply artificial intelligence to sift through the remaining 150,000 anomalies for any further clues.

It turns out that KIC 8462852 or Tabby’s Star, the wildly flickering star that kicked off this whole hunt, is surrounded by dust clouds.

But another flickering star, HD 139139, is even weirder: Its flickering is almost too perfectly random.

“The best thing that can happen now is that larger, more sensitive telescopes monitor these stars as often as they can to look for anything in their light that can give hints to the origin of these peculiarities,” astronomer Phil Plait recently wrote in his Bad Astronomy blog. “Hopefully, too, more stars like these will be found. The more the merrier! I do love a mystery, but I think this one has been going on for long enough now. It’d be nice to start getting some solid answers.”

TECHNOSIGNATURES

Technology isn’t natural. And it shows.

Radio communications use bands of the spectrum not cluttered by natural noise. Lasers emit unnaturally pure colours. Streetlights make the night unnaturally bright.

All these things are, cosmically speaking, strange.

And they’re the latest focus of the search for extraterrestrial intelligence.

They’ve been dubbed technosignatures.

NASA astronomer Joseph Lazio told the Astrobiology Science Conference in June that there were many such possible telltale signs.

“If you see a star, say, blinking on and off faster than a microsecond, that’s not obviously a natural phenomenon,” he said. “(But) it’s not really all that difficult, we can do it today on a lab bench.”

Starships using nuclear fusion propulsion should have visible exhausts. These spectroscopic signatures would be able to be tracked – revealing unnatural acceleration.

And new telescopes are on the brink of being able to peer at the atmospheres of some alien planets. Just as the presence of oxygen indicates life, unnatural pollutants could point to technology.

In the meantime, the 125,000 or so remaining missing stars remain one of our strongest leads.

“We hope to get help from the community to look through the images as a part of a citizen science project. We are looking at ways to do that right now and that will be something we will be able to talk more about at a later date”, the VASCO researchers say.