An Australian team mapping radio waves in the Universe discovered an unusual object that releases a giant burst of energy three times an hour.
The team thinks it could be a neutron star or collapsed cores of stars called a 'white dwarf' with an ultra-powerful magnetic field.
Astrophysicist Dr Natasha Hurley-Walker, from the Curtin University node of the International Centre for Radio Astronomy Research, led the team that made the discovery.
"This object was appearing and disappearing over a few hours during our observations," she said in a statement on Scimex.
"That was completely unexpected. It was kind of spooky for an astronomer because there's nothing known in the sky that does that.
Dr Hurley-Walker says the object is around 4000 light-years away, which is quite close to Earth.
"It's in our galactic backyard," she said.
Objects that turn on and off in the galaxy are known as transients.
"When studying transients, you're watching the death of a massive star or the activity of the remnants it leaves behind," co-author Dr Gemma Anderson said in a statement.
She said the mysterious object was weird because it appeared for a minute at a time.
Transients usually take either a few days or months to disappear for slow ones or a matter of milliseconds for fast ones.
Dr Anderson said the object was extremely bright, had a strong magnetic field and was smaller than the sun.
The object was initially discovered last year by honours student Tyrone O'Doherty using a special telescope in the outback of Western Australia, but the research findings were only published on Thursday.
Dr Hurley-Walker said the observations matched a predicted astrophysical object called an 'ultra-long period magnetar'.
"It's a type of slowly spinning neutron star that has been predicted to exist theoretically," she said in a statement.
"But nobody expected to directly detect one like this because we didn't expect them to be so bright.
"Somehow it's converting magnetic energy to radio waves much more effectively than anything we've seen before."
Dr Hurley-Walker is now monitoring the object and plans to search for more of them.
"More detections will tell astronomers whether this was a rare one-off event or a vast new population we'd never noticed before," she said
She says there is no doubt many more gems will be discovered in the coming years.
