The pages of astronomy books are full of ancient mysteries. Thanks to advances in technology, experts can now look back and solve some of the most knotty space mysteries ever. From the sudden appearance of a “star” 900 years ago above China to the truth behind the famous Wow signal, here are ten cosmic mysteries that have finally been cracked.
Related: 10 historic first images taken from space
10 Antarctica lacked iron meteorites
Some space mysteries exist on Earth. One such conundrum exists in Antarctica. This frosty corner of the globe is where most meteorites are recycled. This abundance has nothing to do with space but instead with color differences. It is easier to detect dark cosmic debris against the white expanse of this region than in places with forests or sand dunes.
Thousands of space rocks enter our atmosphere every year, so you’d think all kinds of meteorites could be found in Antarctica. Not like that. The snow-covered continent is curiously empty of iron meteorites.
The mystery lasted for decades until 2016. That year, British scientists released a study suggesting that Antarctica has lots of iron meteorites—they’re just well hidden. Their iron content ensures that these meteorites will be hotter than other space rocks when they enter our atmosphere. Once they hit ice or snow, they will burrow beneath the surface (melt down, really) and disappear from view entirely. Antarctica probably has a treasure trove of iron-rich meteorites; we just can’t see them.[1]
9 No green comet tails
Astronomers have never recorded a comet with a green tail. This was strange because many comets develop brilliant green heads as they fly closer to the Sun. What kept the color from spreading to their tails? Interestingly, this question remained unsolved for 90 years.
Since the 1930s, scientists suspected that dicarbon could explain it all. Dicarbon is a chemical formed when the organic material on the comet’s head reacts to sunlight, causing the green color. Unfortunately, sunlight also destroys dicarbon, which may explain why the chemical never survives long enough to reach a comet’s tail.
In 2021, this theory was proven in an amazing way. Scientists had to recreate the process, and it was no easy task. Dicarbon is only found in extreme places (like space), and it is also a volatile chemical. In a world first, they created dicarbon, and while it was inside a vacuum chamber, it was exposed to gas and lasers to simulate conditions in space. The lasers in particular showed that the sun’s radiation tore apart the dicarbon before it could turn the green of a comet’s tail.[2]
8 The Mystery of Jovian Lightning
Ancient astronomers theorized for centuries that the largest planet in the solar system had lights, but it wasn’t confirmed until 1979 when NASA’s Voyager 1 spacecraft sped past Jupiter. But in addition to confirming an old suspicion, Voyager 1 also discovered that Jovian illumination only appeared near the planet’s poles. In comparison, Earth’s illumination is more common near the equator.
It took another flyby to understand why lighting bolts avoided Jupiter’s midriff like the plague. In recent years, the Juno spacecraft buzzed Jupiter and identified heat as the reason lightning never swings across the planet’s equator.
Earth catches the brunt of the sun’s heat around the equator which fuels rising warm air – just what lightning needs to form. The process is reversed on Jupiter in a curious way. When sunlight makes Jupiter’s equator toasty, the world’s upper atmosphere stabilizes in such a way that it dampens rising warm air. For this reason, the illumination strikes freely towards the poles where there is no atmospheric stability, and heat from the interior of the planet drives warm air upwards.[3]
7 A strange light show
In 2022, the James Webb telescope sent back a stunning photograph to Earth. It showed a bright light in the center of several rings. Cut through the rings were eight spikes of light that radiated from the center outwards, almost creating a spider web effect. When the bizarre but beautiful image hit social media, people had one question: “What the hell is this?”
Scientists quickly determined that the spikes were an “error” on the part of the telescope. It tended to create such anomalies when photographing bright objects in space. Since the spikes were not real, it left the unusual concentric circles around the star.
A closer look revealed that the “light” came from two stars. They orbited each other in an eight-year cycle, and each time the stars came close to each other and moved away again, that was the moment they produced dust and ejected another ring.[4]
6 The glowing lumps
In 2000, astronomers stumbled upon a bizarre space… thing. Billions of light years from Earth floated a blob. It was as big as a galaxy and also glowed as brightly as one. But here’s the mystery – the giant space bubble had no stars, only hydrogen gas. So, what made it shine so brilliantly?
All in all, about 30 blobs were eventually discovered. However, it wasn’t until dozens of astronomers, countless telescopes and advanced simulations came together that their light source was revealed. Unexpectedly, stars were involved – but in a very unusual way.
It turns out that these mammoth orbs are star factories. Deep within the clumps, fresh stars are produced at a rate 100 times faster than those born in our Milky Way galaxy. For some reason, nearby galaxies also pour star-forming material into the chaos. But the light itself comes from the moment when new stars are born. At that moment, the stars emit a burst of strong ultraviolet light, which spreads into the hydrogen gas, causing the clump to glow.[5]
5 A 900-year-old mystery
In 1181, Japanese and Chinese astronomers noticed a difference in the night sky. A new light had appeared, shone as brightly as Saturn, and remained for six months. The description given by these early stargazers gave modern scientists enough reason to believe they were describing a supernova. This celestial explosion became quite famous in scientific circles, mostly because no one could find any traces of it.
In 2021, about 900 years after the mystery of the missing supernova began, the origin of the so-called “Chinese guest star” was finally discovered. The ancient reports claimed that the light had appeared between the Chinese constellations of Huagai and Chuanshe. In this region was a star and a nebula believed to have been created when two white dwarf stars merged. Such an event is known to trigger supernovae, and the location, description of the light, and age of the nebula all fit the events of 1181.[6]
4 That time when Betelgeuse twinkled
Stargazers are very familiar with Orion. This constellation is also known as “The Hunter”, and Betelgeuse is the red supergiant that marks Orion’s eastern shoulder. The star is among the brightest in the night sky, so when it suddenly faded in September 2019, astronomers quickly noticed. For a while, the fading continued, and by February 2020, Betelgeuse had dimmed by an unprecedented 35 percent.
Although the star regained its former brilliance, experts were at a loss. No one could explain why the red giant had “blinked”. Putting their best guesses on the table, the researchers theorized that the dimming was the result of a dust cloud or a drop in temperature. During a multinational trial, researchers combed through observatory data and satellite images and realized that both theories were correct.
Betelgeuse had ejected a huge cloud of gas from its interior, but it wasn’t until the star’s photosphere began to cool that the gas condensed into dust. This dusty atmosphere temporarily covered the star’s light. [7]
3 The Lunar Fireball photograph
In 1953, Dr. Leon Stuart of Oklahoma photographed an event on the moon. He thought the giant fireball he caught was a plume of vaporized rock. If true, it would make him the first person to witness and document a lunar impact. It became known as “Stuart’s Event”, but no one, not even astronauts or space probes, could find the crater.
Nevertheless, the photograph proved that something had happened on the moon in 1953. In 2003, NASA scientists analyzed the image and calculated that the object would have left a fresh crater up to 2 kilometers in diameter. Taking clues from the lunar landscape, they searched a roughly 22-mile (35-kilometer) grid of photographs taken in 1994 by the lunar orbiter Clementine.
Amazingly, the NASA team found Stuart’s crater. It was smaller, measuring 0.93 miles (1.5 kilometers) in diameter, but it was fresh, had the right appearance, and was also located in the center of the famous photograph. The size of the crater also matched the estimated energy output from the impact, which would have been 35 times more powerful than the atomic bomb that had devastated Hiroshima.[8]
2 The Impossible Twin Galaxies
No two galaxies are alike. With this rule in mind, scientists were blown away when they discovered identical twin galaxies in 2013. The pair even sat next to each other, making it immediately obvious that they were insanely similar. The odd phenomenon became known as Hamilton’s object.
Neither theory made sense until someone suggested, in 2015, that gravitational lensing might be responsible. This rare phenomenon is crazy. When large celestial bodies line up in a row, they can actually bend light and spacetime in such a way that when astronomers look at the objects through telescopes, they appear closer than they really are. Very often they also produce mirages of themselves. The result? The illusion that two identical objects are sitting side by side.
When scientists took a closer look at the lineup that might cause Hamilton’s objects, they discovered that between Earth and the “twins” sat a massive cluster of galaxies. The latter causes the double effect, but in reality Hamilton’s object is a single spiral galaxy.[9]
1 The origin of the Wow signal
In 1977, a legendary mystery was born. Astronomer Jerry Ehman caught radio waves from space unlike anything he had ever seen before (or anyone else for that matter). He wrote “Wow!” next to the printed signal, and the name stuck. To this day, the Wow signal is said to be proof of extraterrestrial contact or at least an unsolved mystery. In fact, the origin had already been discovered in 2017.
Researchers from St Petersburg College suspected that comets might be the culprit. More specifically a pair called 266P/Christensen and 335P/Gibbs. Both were encased in clouds of hydrogen gas. This detail is important because hydrogen naturally emits 1420MHz. This was the same radio frequency that the “alien” signal was emitting.
The telescope that picked up the Wow signal pointed to a specific group of stars in the constellation Sagittarius, and both comets were confirmed to have been in the area at the time. A closer look also revealed that 266/P Christensen was probably the comet that triggered the 40-year mystery. When its radio signals were compared to those of the Wow signal, they were a match.[10]
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