After being in the virtual realm, June 30 marks the return of in person Asteroid Day with the event taking place in Luxembourg, with Asteroid Day Live 2022.
What is Asteroid Day?
Asteroid Day, also known as International Asteroid Day, is an annual global event which is held on the anniversary of the Tunguska event in 1908, when an asteroid leveled about 2,150 square kilometres (830 sq mi) forest in Siberia.
Rod: A creative force, blending words, images, and flavors. Blogger, writer, filmmaker, and photographer. Cooking enthusiast with a sci-fi vision. Passionate about his upcoming series and dedicated to TNC Network. Partnered with Rebecca Washington for a shared journey of love and art.
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Rod: A creative force, blending words, images, and flavors. Blogger, writer, filmmaker, and photographer. Cooking enthusiast with a sci-fi vision. Passionate about his upcoming series and dedicated to TNC Network. Partnered with Rebecca Washington for a shared journey of love and art.
This image overlays over 100 fireball images recorded between 2016 and 2020. The streaks are fireballs; the dots are star positions at different times.
Desert Fireball NetworkPatrick M. Shober, NASA
Much of what scientists know about the early solar system comes from meteorites – ancient rocks that travel through space and survive a fiery plunge through Earth’s atmosphere. Among meteorites, one type – called carbonaceous chondrites – stands out as the most primitive and provides a unique glimpse into the solar system’s infancy.
The carbonaceous chondrites are rich in water, carbon and organic compounds. They’re “hydrated,” which means they contain water bound within minerals in the rock. The components of the water are locked into crystal structures. Many researchers believe these ancient rocks played a crucial role in delivering water to early Earth.
Before hitting the Earth, rocks traveling through space are generally referred to as asteroids, meteoroids or comets, depending on their size and composition. If a piece of one of these objects makes it all the way to Earth, it becomes a “meteorite.”
From observing asteroids with telescopes, scientists know that most asteroids have water-rich, carbonaceous compositions. Models predict that most meteorites – over half – should also be carbonaceous. But less than 4% of all the meteorites found on Earth are carbonaceous. So why is there such a mismatch?
In a study published in the journal Nature Astronomy on April 14, 2025, my planetary scientist colleagues and I tried to answer an age-old question: Where are all the carbonaceous chondrites?
Sample-return missions
Scientists’ desire to study these ancient rocks has driven recent sample-return space missions. NASA’s OSIRIS‑REx and JAXA’s Hayabusa2 missions have transformed what researchers know about primitive, carbon‑rich asteroids.
Meteorites found sitting on the ground are exposed to rain, snow and plants, which can significantly change them and make analysis more difficult. So, the OSIRIS‑REx mission ventured to the asteroid Bennu to retrieve an unaltered sample. Retrieving this sample allowed scientists to examine the asteroid’s composition in detail.
Similarly, Hayabusa2’s journey to the asteroid Ryugu provided pristine samples of another, similarly water-rich asteroid.
Together these missions have let planetary scientists like me study pristine, fragile carbonaceous material from asteroids. These asteroids are a direct window into the building blocks of our solar system and the origins of life.
Carbonaceous near-Earth asteroid Bennu as seen from NASA’s OSIRIS-REx sample-return spacecraft.NASA
The carbonaceous chondrite puzzle
For a long time, scientists assumed that the Earth’s atmosphere filtered out carbonaceous debris.
When an object hits Earth’s atmosphere, it has to survive significant pressures and high temperatures. Carbonaceous chondrites tend to be weaker and more crumbly than other meteorites, so these objects just don’t stand as much of a chance.
Meteorites usually start their journey when two asteroids collide. These collisions create a bunch of centimeter- to meter-size rock fragments. These cosmic crumbs streak through the solar system and can, eventually, fall to Earth. When they’re smaller than a meter, scientists call them meteoroids.
Meteoroids are far too small for researchers to see with a telescope, unless they’re about to hit the Earth, and astronomers get lucky.
But there is another way scientists can study this population, and, in turn, understand why meteorites have such different compositions.
Meteor and fireball observation networks
Our research team used the Earth’s atmosphere as our detector.
Most of the meteoroids that reach Earth are tiny, sand-sized particles, but occasionally, bodies up to a couple of meters in diameter hit. Researchers estimate that about 5,000 metric tons of micrometeorites land on Earth annually. And, each year, between 4,000 and 10,000 large meteorites – golf ball-sized or larger – land on Earth. That’s more than 20 each day.
A fireball observed by the FRIPON network in Normandy, France, in 2019.
Today, digital cameras have rendered round-the-clock observations of the night sky both practical and affordable. Low-cost, high-sensitivity sensors and automated detection software allow researchers to monitor large sections of the night sky for bright flashes, which signal a meteoroid hitting the atmosphere.
Research teams can sift through these real-time observations using automated analysis techniques – or a very dedicated Ph.D. student – to find invaluable information.
Our team manages two global systems: FRIPON, a French-led network with stations in 15 countries; and the Global Fireball Observatory, a collaboration started by the team behind the Desert Fireball Network in Australia. Together with other open-access datasets, my colleagues and I used the trajectories of nearly 8,000 impacts observed by 19 observation networks spread across 39 countries.
FRIPON camera installed at the Pic du Midi Observatory in the French Pyrenees.FRIPON
By comparing all meteoroid impacts recorded in Earth’s atmosphere with those that successfully reach the surface as meteorites, we can pinpoint which asteroids produce fragments that are strong enough to survive the journey. Or, conversely, we can also pinpoint which asteroids produce weak material that do not show up as often on Earth as meteorites.
Desert Fireball Network automated remote observatory in South Australia.The Desert Fireball Network
The Sun is baking the rocks too much
Surprisingly, we found that many asteroid pieces don’t even make it to Earth. Something starts removing the weak stuff while the fragment is still in space. The carbonaceous material, which isn’t very durable, likely gets broken down through heat stress when its orbit takes it close to the Sun.
As carbonaceous chondrites orbit close, and then away from the Sun, the temperature swings form cracks in their material. This process effectively fragments and removes weak, hydrated boulders from the population of objects near the Earth. Anything left over after this thermal cracking then has to survive the atmosphere.
Only 30%-50% of the remaining objects survive the atmospheric passage and become meteorites. The debris pieces whose orbits bring them closer to the Sun tend to be significantly more durable, making them far more likely to survive the difficult passage through Earth’s atmosphere. We call this a survival bias.
For decades, scientists have presumed that Earth’s atmosphere alone explains the scarcity of carbonaceous meteorites, but our work indicates that much of the removal occurs beforehand in space.
Going forward, new scientific advances can help confirm these findings and better identify meteoroid compositions. Scientists need to get better at using telescopes to detect objects right before they hit the Earth. More detailed modeling of how these objects break up in the atmosphere can also help researchers study them.
Lastly, future studies can come up with better methods to identify what these fireballs are made of using the colors of the meteors.
Patrick M. Shober, Postdoctoral Fellow in Planetary Sciences, NASA
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Black holes, like the one in this illustration, can spray powerful jets.
S. Dagnello (NRAO/AUI/NSF), CC BY-SADavid Garofalo, Kennesaw State University
One of the most powerful objects in the universe is a radio quasar – a spinning black hole spraying out highly energetic particles. Come too close to one, and you’d get sucked in by its gravitational pull, or burn up from the intense heat surrounding it. But ironically, studying black holes and their jets can give researchers insight into where potentially habitable worlds might be in the universe.
As an astrophysicist, I’ve spent two decades modeling how black holes spin, how that creates jets, and how they affect the environment of space around them.
What are black holes?
Black holes are massive, astrophysical objects that use gravity to pull surrounding objects into them. Active black holes have a pancake-shaped structure around them called an accretion disk, which contains hot, electrically charged gas.
The plasma that makes up the accretion disk comes from farther out in the galaxy. When two galaxies collide and merge, gas is funneled into the central region of that merger. Some of that gas ends up getting close to the newly merged black hole and forms the accretion disk.
There is one supermassive black holeat the heart of every massive galaxy.
Black holes and their disks can rotate, and when they do, they drag space and time with them – a concept that’s mind-boggling and very hard to grasp conceptually. But black holes are important to study because they produce enormous amounts of energy that can influence galaxies.
How energetic a black hole is depends on different factors, such as the mass of the black hole, whether it rotates rapidly, and whether lots of material falls onto it. Mergers fuel the most energetic black holes, but not all black holes are fed by gas from a merger. In spiral galaxies, for example, less gas tends to fall into the center, and the central black hole tends to have less energy.
One of the ways they generate energy is through what scientists call “jets” of highly energetic particles. A black hole can pull in magnetic fields and energetic particles surrounding it, and then as the black hole rotates, the magnetic fields twist into a jet that sprays out highly energetic particles.
Magnetic fields twist around the black hole as it rotates to store energy – kind of like when you pull and twist a rubber band. When you release the rubber band, it snaps forward. Similarly, the magnetic fields release their energy by producing these jets.
The accretion disk around a black hole can form a jet of hot, energetic particles surrounded by magnetic field lines.NASA, ESA, and A. Feild (STScI), CC BY
These jets can speed up or suppress the formation of stars in a galaxy, depending on how the energy is released into the black hole’s host galaxy.
Rotating black holes
Some black holes, however, rotate in a different direction than the accretion disk around them. This phenomenon is called counterrotation, and some studies my colleagues and I have conducted suggest that it’s a key feature governing the behavior of one of the most powerful kinds of objects in the universe: the radio quasar.
Radio quasars are the subclass of black holes that produce the most powerful energy and jets.
You can imagine the black hole as a rotating sphere, and the accretion disk as a disk with a hole in the center. The black hole sits in that center hole and rotates one way, while the accretion disk rotates the other way.
This counterrotation forces the black hole to spin down and eventually up again in the other direction, called corotation. Imagine a basketball that spins one way, but you keep tapping it to rotate in the other. The tapping will spin the basketball down. If you continue to tap in the opposite direction, it will eventually spin up and rotate in the other direction. The accretion disk does the same thing.
Since the jets tap into the black hole’s rotational energy, they are powerful only when the black hole is spinning rapidly. The change from counterrotation to corotation takes at least 100 million years. Many initially counterrotating black holes take billions of years to become rapidly spinning corotating black holes.
So, these black holes would produce powerful jets both early and later in their lifetimes, with an interlude in the middle where the jets are either weak or nonexistent.
When the black hole spins in counterrotation with respect to its accretion disk, that motion produces strong jets that push molecules in the surrounding gas close together, which leads to the formation of stars.
But later, in corotation, the jet tilts. This tilt makes it so that the jet impinges directly on the gas, heating it up and inhibiting star formation. In addition to that, the jet also sprays X-rays across the galaxy. Cosmic X-rays are bad for life because they can harm organic tissue.
For life to thrive, it most likely needs a planet with a habitable ecosystem, and clouds of hot gas saturated with X-rays don’t contain such planets. So, astronomers can instead look for galaxies without a tilted jet coming from its black hole. This idea is key to understanding where intelligence could potentially have emerged and matured in the universe.
Black holes as a guide
By early 2022, I had built a black hole model to use as a guide. It could point out environments with the right kind of black holes to produce the greatest number of planets without spraying them with X-rays. Life in such environments could emerge to its full potential.
Looking at black holes and their role in star formation could help scientists predict when and where life was most likely to form.
Where are such conditions present? The answer is low-density environments where galaxies had merged about 11 billion years ago.
These environments had black holes whose powerful jets enhanced the rate of star formation, but they never experienced a bout of tilted jets in corotation. In short, my model suggested that theoretically, the most advanced extraterrestrial civilization would have likely emerged on the cosmic scene far away and billions of years ago.
David Garofalo, Professor of Physics, Kennesaw State University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Did James Webb Find Life on a Distant Planet Recently?
Recent findings from the James Webb Space Telescope suggest potential biosignatures on exoplanet K2-18b, including dimethyl sulfide, indicating possible microbial life, though further research is necessary.
James Webb Space Telescope mission observing universe. This image elements furnished by NASA
While the answer to that question is not a definitive “yes,” recent findings from the James Webb Space Telescope (JWST) are providing what scientists are calling the “strongest evidence yet” of potential life on an exoplanet, specifically K2-18b. This discovery opens a new frontier in our understanding of the universe and the possibility of life beyond Earth.
The Discovery
A dedicated team of astronomers recently utilized the powerful capabilities of the JWST to analyze the atmosphere of K2-18b, a super-Earth exoplanet located an incredible 124 light-years away from our planet. Their findings have revealed chemical signatures in the atmosphere that warrant further investigation.
The Biosignature
Among the intriguing detections was dimethyl sulfide (DMS) and potentially dimethyl disulfide (DMDS). These compounds are significant because, on Earth, they are predominantly produced by living organisms, with marine microbes being the primary source. The presence of these chemicals in K2-18b’s atmosphere suggests the potential for biological processes at work.
The Context
DMS is primarily emitted by marine phytoplankton, a crucial element of oceanic ecosystems. The detection of DMS in the atmosphere of K2-18b is interpreted as a potential indicator of microbial life, potentially thriving in an ocean on the planet. This tantalizing prospect encourages scientists to contemplate the types of ecosystems that could flourish far beyond Earth.
Caution
However, it is essential to approach these findings with the appropriate level of caution. While the presence of these compounds is compelling, scientists emphasize that this does not serve as definitive confirmation of life. Further observations and rigorous analyses are necessary to rule out other non-biological explanations for the presence of DMS and DMDS in K2-18b’s atmosphere.
Significance
This detection represents a significant leap forward in the ongoing quest to uncover extraterrestrial life. It is the first time scientists have successfully identified potential biosignatures on an exoplanet using advanced astronomical technology. This marks a pivotal moment in astrobiology, helping to narrow the focus of future exploration.
Future Research
The JWST will continue to play a vital role in studying K2-18b, as well as other exoplanets, in the relentless pursuit of knowledge about life in the cosmos. Ongoing research will seek to deepen our understanding and potentially corroborate these exciting initial findings.
In conclusion, while the James Webb Space Telescope has not definitively found life on K2-18b, the detection of biosignatures in its atmosphere represents a groundbreaking step in humanity’s exploration of worlds beyond our own. As scientists push forward, we stand on the brink of potentially transformative discoveries that could change our understanding of life in the universe. Stay tuned for further updates as we journey into the stars!
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