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Mysterious radio signals -

Since 2007, researchers have detected fast radio bursts (FRBs), intense radio signals lasting just milliseconds and originating billions of light-years away. Recently, a repeating FRB was captured flashing six times, but the mystery behind these signals still endures.

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Nuclear pasta -

The strongest substance in the universe forms from a dead star's remnants, where extreme gravitational pressure compresses protons and neutrons into tangled, linguini-like material. Simulations suggest this substance would break only under 10 billion times the force required to shatter steel.

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Haumea’s rings -

Haumea, a dwarf planet in the Kuiper Belt, is unique with its elongated shape, two moons, and fast four-hour rotation. In 2017, astronomers discovered thin rings around Haumea, likely caused by a past collision, making it even more unusual.

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Dark matter -

The invisible force known as dark matter makes up 85% of the universe's substance, and it is puzzling yet omnipresent. However, in March 2018, astronomers discovered a galaxy seemingly lacking dark matter. Later research confirmed its presence, and astronomers remain baffled!

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The most bizarre star -

Astronomer Tabetha Boyajian and her team were puzzled by KIC 846285, or Tabby's star, which experienced irregular and significant dips in brightness. While some speculated about an alien megastructure surrounding it, most now believe the dimming is caused by an unusual ring of dust surrounding the star.

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Highly electric Hyperion -

Saturn's moon Hyperion (with its pumice-like, irregular shape and numerous craters) ranks among the solar system's weirdest moons. NASA's Cassini spacecraft, which explored Saturn from 2004 to 2017, also discovered that Hyperion emits a "particle beam" of static electricity into space, adding to its oddity.

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A guiding neutrino -

A high-energy neutrino (which is basically a tiny ghost particle) struck Earth on September 22, 2017, which wasn't unusual by itself, but it was the first with enough data to trace its origin. Astronomers identified that it was flung four billion years ago by a flaring blazar, a supermassive black hole consuming nearby material.

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The living fossil galaxy -

A galaxy known as DGSAT I was discovered in 2016, and is as large as the Milky Way but nearly invisible due to its sparsely spread stars. Unlike typical galaxies found in clusters, DGSAT I sits alone. Its characteristics suggest it formed around a billion years after the Big Bang, making it a living fossil.

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Double quasar image -

Massive objects can curve light, distorting the image of objects behind them. Using the Hubble Space Telescope, researchers observed a quasar (a luminous galaxy) from the early universe and found the universe is expanding faster today than it was then. Physicists now must determine whether their theories are flawed or if something unusual is occurring.

Image credit: NASA Hubble Space Telescope, Tommaso Treu/UCLA

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Infrared stream -

Neutron stars are dense remnants of dead stars, usually emitting radio waves or X-rays. In September 2018, astronomers discovered an unusual stream of infrared light from a neutron star 800 light-years away, a first. They suspect a surrounding dust disk could be causing this, but the exact explanation remains unknown.

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Rogue planet with auroras -

Rogue planets, ejected from their parent stars by gravitational forces, drift through the galaxy without an orbit. A planet-sized object (named SIMP J01365663+0933473 and located 200 light-years away) stands out with a magnetic field over 200 times stronger than Jupiter's. This powerful field creates flashing auroras visible with radio telescopes.

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Black hole Sagittarius A* -

A supermassive black hole, Sagittarius A* (Sgr A*), resides at the center of the Milky Way, containing four million solar masses. Unlike more active black holes in other galaxies, Sgr A* is unusually quiet, hidden behind gas and dust but detectable through radio waves. Its extreme density remains a mystery, challenging our understanding of physics.

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Pulsar planets -

The first planets discovered beyond our solar system were found in 1992, not around a normal star, but orbiting a millisecond pulsar located 980 light-years away. Pulsars are neutron stars, incredibly dense objects that rotate rapidly, emitting electromagnetic energy like a lighthouse beam. Even though the planets circle the pulsar, it is no bigger than 20 miles (32 kilometers) wide.

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Hoag’s Object -

In 1950, astronomer Arthur Hoag discovered a galaxy that features a central yellow core, separated by 70,000 light-years of near-emptiness from an outer ring of stars, gas, and dust. The galaxy, known as Hoag’s Object, has a core and outer ring that are each similar in size to parts of the Milky Way, making it one of the universe’s most peculiar galactic structures.

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Fermi bubbles -

In November 2010, astronomers discovered two enormous bubbles of gamma rays emanating from the Milky Way’s center. These bubbles, expanding at 2.2 million mph (3.5 million km/h), form an hourglass shape. This strange structure adds to the growing list of mysterious cosmic phenomena.

Image credit: NASA's Goddard Space Flight Center

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Magnetars -

Magnetars are a type of neutron star with incredibly strong magnetic fields, about a quadrillion times stronger than Earth's magnetic field. They are strange because they can emit "starquakes" caused by the shifting of their magnetic field, releasing massive amounts of energy in intense bursts of radiation that can be detected from Earth.

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The Boötes Void -

The Boötes Void is a massive, nearly empty region of space about 700 million light-years across, with very few galaxies inside it. Its size and emptiness are strange because such voids are rare in the universe, which is mostly filled with galaxies and matter.

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The Great Attractor -

The Great Attractor is a gravitational anomaly that appears to be pulling galaxies, including our own Milky Way, toward it at incredible speeds. It's strangely located in a part of the sky obscured by the our galaxy’s dust, making it difficult to observe directly. We know it's there, but its exact nature remains a mystery.

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The cold spot -

The cold spot is an unusually cold region in the cosmic microwave background (CMB) being recorded from the universe in the afterglow of the Big Bang. It can be seen in the center of the image here, and its temperature is significantly lower than the surrounding area. But scientists aren't sure why. It remains one of the biggest puzzles in cosmology.

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‘Oumuamua -

‘Oumuamua was an elongated, cigar-shaped object that passed through our solar system in 2017, the first known interstellar object detected. Its odd shape, high speed, and the fact that it didn't behave like a typical comet or asteroid have led to speculation about its origins. Some scientists have even suggested it might be an alien probe.

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Hanny's Voorwerp -

Hanny's Voorwerp is a strange, glowing, greenish object thought to be a cloud of gas illuminated by a quasar that has since gone dormant. What's odd is that it continues to glow long after the quasar's energy output should have faded. This suggests that quasars can leave behind echoes of their activity and illuminate space for millions of years after.

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Hypervelocity stars -

When stars move through space at speeds so fast that they can escape their galaxies entirely, they are known as hypervelocity stars. Most stars in galaxies orbit at relatively stable speeds, but these stars are believed to have been ejected after interacting with supermassive black holes.

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Wormholes -

Wormholes are theoretical passages through spacetime that could connect distant parts of the universe, or even different universes. Although they've never been observed, they arise from solutions to Albert Einstein's equations of general relativity, and traveling through one could cause faster-than-light travel and the potential for time travel.

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The Wow! signal -

In 1977, a strong, narrowband radio signal was detected for 72 seconds before it disappeared. It came from the constellation Sagittarius and remains unexplained to this day. The signal's sudden appearance and the fact that it was never detected again have led to wild speculation, including the possibility that it was a transmission from an alien civilization.

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Galactic cannibalism -

Galactic cannibalism is a phenomenon where a larger galaxy consumes a smaller one by gravitationally pulling it apart and absorbing its stars, gas, and dust. Galaxies (which seem like stable, self-contained systems) can actually merge and devour each other in cosmic collisions that lead to larger, more massive galaxies.

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Blue stragglers -

Blue stragglers are stars that appear younger and more massive than the other stars in their clusters, despite being formed from the same material. They're strange because they defy the expected life cycle of stars; these stars should have already burned out, yet they remain bright and hot, traveling inexorably through the universe.

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The Phoenix Cluster -

The Phoenix Cluster is a massive galaxy cluster with an unusually high rate of star formation and black hole activity. In most galaxy clusters, star formation has slowed down significantly, but the Phoenix Cluster shows stars forming at a rapid pace, and the supermassive black hole at its center is growing much faster than expected.

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Saturn's hexagon -

Saturn's north pole hosts a strange, persistent cloud formation in the shape of a hexagon. This geometric weather pattern is bizarre and unclear, because most storms or atmospheric phenomena on planets are circular or irregular in shape. The hexagon is over 18,600 miles (30,000 kilometers) wide and has winds reaching 200 mph (320 km/h).

Sources: (Live Science) (Astronomy Magazine) (Smithsonian Magazine) (Britannica) (NASA Science)

See also: Can we clean up space junk?

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