Space is often called the final frontier, a place which is still largely unexplored by humans. Though we're still a long way from sending humans to Mars (let alone another solar system) technology like the James-Webb Space Telescope does allow us to peer into the void. Let's take a look at...
- The disintegrating planet with a comet's tail
- The exoplanet with (potential) signs of life
- The star that consumed a planet (and got indigestion)
- The ammonia hailstorms of Jupiter
- The dark nebula firing molecular jets
- The cryovolcanic "devil comet"
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| Dark nebulae exist throughout the Milky Way... and beyond. (Kanenori) |
The Disintegrating Planet With a Comet's Tail
There's a binary star system sitting around 140 light years from Earth in the Pegasus constellation. That's nothing special - what makes this little cluster special is the presence of a dying planet, shedding material equivalent to the mass of Mount Everest with each completed orbit.
The planet (dubbed BD+05 4868 Ab) is around the size of Mercury and has a very tight orbit - approximately 20 times closer than Mercury gets to our own Sun. It's also going incredibly fast, completing an orbit every 30.5 hours. These factors have combined to heat the surface so much it has become magma, with the liquefied rock boiling off into space as it whirls through the void.
Scientists believe that BD+05 4868 Ab will have fully disintegrated in a couple of million years... but for now, a tail of molten rock 9 million kilometers long trails behind the doomed world like a planet-sized comet.
The Exoplanet With (Potential) Signs of Life
In 2025 a group of Cambridge researchers caused quite a stir when they announced promising evidence of alien life on the exoplanet K2-18b. They claimed that the small, Neptune-like planet showed signs of having dimethyl sulfide or dimethyl disulfide in the atmosphere - on planet Earth these only occur due to lifeforms, typically marine microbes.
K2-18b orbits a cool dwarf star in the Leo constellation around 124 light years from Earth. It's thought to be in the "Goldilocks zone" which is a distance from the star that would give it good conditions for life to flourish.
Unfortunately other researchers say that the data from the James-Webb telescope isn't so clear cut. They point out that the tell-tale sulfide readings are so weak that they may not actually exist - with some even suggesting that the distant planet may actually be covered in oceans of molten rock rather than livable liquid!
The Star That Consumed a Planet (and Got Indigestion)
In 2020 the star ZTF SLRN-2020 had become 100 times brighter in just 10 days. Researchers initially believed this might have been caused by two stars merging, but things didn't quite add up. For one thing, the star didn't output anywhere near the amount of energy you would expect from the collision of two stellar bodies. For another, ZTF SLRN-2020 was now surrounded by a cloud of comparatively cool gas or dust.
Scientists now believe that the victim of this hungry star was actually a gas giant similar to Jupiter. This would explain the noticeable but comparatively small increases in energy as the star engulfed the planet.
The ZTF SLRN-2020 didn't have things entirely it's own way though. It seems that as the doomed planet fell into the star, its own gravity tore a large amount of gas away from the stellar surface which belched out to form a cool cloud around the star.
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| Comets are spectacular enough, but the "Devil Comet" also seems to have horns... (TheOtherKev) |
The Ammonia Hailstorms of Jupiter
The gas giant Jupiter is a turbulent place - even though we can only see the tops of clouds, it's obvious that massive weather-systems constantly churn the atmosphere. This meant that it was something of a surprise to the scientists who found that large pockets (some of them 150km deep) of the storm-wracked sky were depleted of ammonia - with no obvious explanation.
One storm observed by the NASA Juno probe may have provided the answer. During a flyby in 2017 the spacecraft identified high concentrations of ammonia and water sitting beneath the cloud. The explanations that fit all involved melting ice... with the culprit being gigantic ammonia-rich hailstones that the researchers called "mushballs."
The theory goes that particles of ammonia-rich ice are swept up by the violent storms of Jupiter. These particles are then "juggled" inside the clouds, accumulating water much like a hailstone on Earth. Finally the dense stones fall deeper into Jupiter than the ammonia-rich particles originated from, depleting ammonia and water levels in the upper clouds.
The Dark Nebula Firing Molecular Jets
Containing 250,000 times the mass of our sun and stretching for 180 light years, the Circinus molecular cloud is a dark nebula of cold gas and dust that blocks the passage of light. It sits around 2,500 light years from Earth in the Circinus constellation, where it periodically produces stars.
Scientists know that the nebula is producing protostars (stars that are still gathering mass) thanks to the intense molecular outflows they occasionally vent. These plumes of energetic material punch holes through the cloud, giving away the position of the protostars like the flash of a sniper rifle.
The Cryovolcanic "Devil Comet"
Roughly every 70 years, Earth is graced with an ominous celestial visitor - a green comet that sometimes appears to have horns.
The Pons-Brooks comet was first "officially" discovered in 1812 by Jean-Louis Pons (though it has likely been seen even further back) and again in 1883 by William Robert Brooks. It's thought to be about 34km across and appears green because of the dicarbon it contains.
The horns occasionally seen on the comet have another explanation - Pons-Brooks is cryovolcanic, meaning that it can erupt plumes of gas, dust and ice. This usually occurs when it becomes heated and core pressure rises, something that can happen when it passes close to the Sun. The pressurized material is eventually forced out of the comet, with weak points in the crust causing two separate plumes to emerge!
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