Space is unbelievably vast and shrouded in mystery, and the 10 mysterious things we’ve uncovered so far only deepen the intrigue. While humanity may never fully chart every corner of the cosmos, every new oddity—be it a strange object, an unexplained signal, or a bizarre void—reminds us just how much remains unknown.
10 Mysterious things that stretch our imagination
Back in October 2017, a baffling visitor slipped through our solar system and was christened Oumuamua. It zipped past the Sun at a distance of merely a quarter of the Earth‑Sun gap before suddenly picking up speed and shooting out of the system.
The scientific community remains split on its true nature and the cause of that unexpected boost. Some argue it behaves like an odd comet, while others suggest an asteroid, a sub‑planetary fragment, a solar‑sail spacecraft, or even a massive ice chunk torn from a shattered world.
Harvard researchers Shmuel Bialy and Avi Loeb lean toward the solar‑sail hypothesis, proposing that an alien‑engineered, sunlight‑driven sail could explain the acceleration.
In contrast, NASA’s Zdenek Sekanina contends Oumuamua is a comet lacking a visible tail, hypothesizing that it shed its volatile gases when it brushed too close to the Sun.
Gregory Laughlin’s Yale team also sees ice as the primary component, but they reject the comet label, instead suggesting it originated from a broken icy planet that was ejected after a close encounter with a larger neighbor.
Amaya Moro‑Martin of the Space Telescope Science Institute adds another angle: perhaps Oumuamua is the leftover core of a planet that never finished forming, flung into interstellar space before its birth was complete.
9 Tabby’s Star
In 2011, Kepler data revealed a puzzling pattern from the star KIC 8462852—better known as Tabby’s Star—where its brightness would dip irregularly before brightening again.
Scientists tossed around several explanations: a swarm of comets, unknown interstellar material, or even dust surrounding a distant black hole could be casting shadows.
One especially sensational idea proposed that an advanced civilization might have erected a megastructure that intermittently blocked the star’s light, sparking a flurry of speculation.
Follow‑up observations in May 2017, using dozens of telescopes, dismissed the megastructure theory because such a construct would block all wavelengths uniformly, not just cause selective dimming.
Instead, the consensus shifted toward a cloud of dust orbiting the star, though the exact origin of that dust remains elusive. Some hypothesize that an unseen planetary body could be generating the dust as it disintegrates.
Further support came from Columbia’s Brian Metzger in 2016, who suggested a planet or moon might have been ripped apart by the star’s gravity, sprinkling debris into orbit.
8 FRB 121102
Fast Radio Bursts, or FRBs, are fleeting yet powerful radio flashes from deep space. While most vanish after a single burst, FRB 121102 has stubbornly repeated, giving astronomers a rare, persistent puzzle.
Since its first detection on 2 November 2012, over 150 bursts have been logged, all traced back to a galaxy roughly three billion light‑years away, though the exact source within that galaxy remains unidentified.
One leading theory points to a highly magnetized neutron star, while another daring hypothesis suggests an alien technology could be beaming the signals as propulsion power for spacecraft.
However, the alien scenario is tempered by the timing—these bursts occurred billions of years before humans existed, making intentional communication improbable.
7 The Dark Flow
A cluster of distant galaxies has been observed racing away at a staggering 1.6 million km/h, a motion that defies current cosmological models and has been dubbed “the dark flow.”
Scientists speculate that an unseen massive entity—perhaps a gigantic gravitational attractor—could be pulling these galaxies en masse, though its exact nature and location remain a mystery.
While the flow currently carries the galaxies away from Earth, future observations will determine whether this trajectory might someday reverse, drawing them toward us.
6 The Cow
June 2018 delivered a spectacular flash in the Hercules constellation, dubbed AT2018cow—or simply “The Cow”—bright enough to rival the combined output of 10 to 100 supernovae.
Its brilliance persisted for roughly two weeks before fading, prompting astronomers to examine its X‑ray and ultraviolet signatures.
One interpretation suggests a black hole devouring a white dwarf, while alternative views argue that a newly formed black hole or neutron star—born from a stellar death—could be responsible for the outburst.
5 A Mysterious Signal From a Sun‑Like Star
On 15 May 2015, the Russian RATAN‑600 telescope caught a puzzling radio burst emanating from HD 164595, a star remarkably similar to our Sun, differing by only a percent in mass and being 100 million years younger.
Some researchers speculated an extraterrestrial origin, noting that the system also hosts a Neptune‑like planet, HD 164595 b, hinting at the possibility of additional, perhaps Earth‑like, worlds.
Critics, however, point out that the signal went unreported for a full year, and the RATAN‑600’s design makes precise localization difficult, casting doubt on the star’s involvement.
Moreover, powering such a transmission would demand roughly 50 trillion watts—far exceeding Earth’s total energy consumption—making an intentional alien beacon seem unlikely.
4 A Mysterious Supervoid That Is One of the Largest Objects in Space
Cosmic voids—vast regions nearly empty of galaxies—can swell into supervoids, each capable of housing up to ten thousand galaxies, though most remain sparsely populated.
The supervoid highlighted here ranks among the biggest ever catalogued, situated three billion light‑years away, so immense that even light would need hundreds of millions of years to cross it.
Three‑dimensional mapping revealed that this void not only sucks in light energy but also expands continually as the universe stretches.
3 Mysterious Radio Signals From the M82 Galaxy
May 2009 saw British astronomers stumble upon steady radio waves while monitoring an explosive event in the nearby M82 galaxy.
Typical cosmic radio bursts swell then fade over weeks, yet the M82 emissions held steady despite the source moving at extreme velocities.
One hypothesis attributes the signal to the galaxy’s central supermassive black hole, a common radio emitter, though the origin appears offset from the core.
Another theory proposes a microquasar—a smaller black hole born from a massive star’s collapse—though such objects usually emit both radio and X‑ray radiation, which this source lacks, suggesting an unusual environment might suppress X‑ray output.
2 CMB Cold Spots
The cosmic microwave background (CMB) is the lingering glow of the Big Bang, but it contains puzzling cold patches where temperatures dip unexpectedly.
While some scientists argue these cold spots could be linked to enormous supervoids, two Durham University researchers, Tom Shanks and Ruari Mackenzie, suggest they may instead mark collisions between our universe and a neighboring universe.
Their analysis of light from thousands of galaxies shows each cold spot surrounded by a series of smaller voids and galaxy clusters, supporting a multiverse‑collision scenario, though conventional physics still offers alternative explanations.
1 The Zombie Star
Supernovae signal a star’s final breath, yet the object known as iPTF14hls defied expectations by exploding not once but twice—first observed in 1954 and then again a decade later in 2014.
Initially, astronomer Iair Arcavi thought a different star had wandered into the same spot, but subsequent data confirmed it was the same massive star, earning the nickname “Zombie Star” for its uncanny resurrection.
While some theorize that stars exceeding a hundred solar masses may frequently undergo multiple explosions, current observations suggest iPTF14hls may finally be done, though its prolonged two‑year brightness leaves open the possibility of future outbursts.