On Oct. 7, 2008, just after midnight UTC, an asteroid 4 meters across came screaming into Earths atmosphere.
It started feeling pressure from the thin air around 100 kilometers above the ground. Traveling at a downward angle of about 20 at 46,000 kilometers per hour a dozen times faster than a rifle bullet the building pressure as it rammed through ever-denser air caused the gas in front of it to be violently compressed and heat up, so much so that the asteroid heated up as well. Both the air in front and the asteroid itself started to glow by the time it was 70 km above the Earth. Seconds later, around 42 kilometers and then again at 37 km up, it partially exploded, then one second later a final pulse of energy caused the asteroid to completely disintegrate.
The total energy released was equivalent to over a thousand tons of TNT exploding, much of that in the form of a debris cloud expanding away. It contained dust and rocks, the remains of the original 80 tons of material making up the asteroid. This then rained meteorites down onto the ground, a region of the Sudans Nubian Desert in Africa, with meteorites ranging in size from specks of dust to ones that weighed several hundred grams.
The asteroid, called 2008 TC3, had been discovered just 19 hours previously in images taken by the Catalina Sky Survey, which sweeps the sky looking for dangerous near-Earth asteroids. An alert was sent out, more observations taken, and it quickly became clear this rock was going to hit Earth: The very first time one was ever seen before impact. Over 900 observations were made in that time by professional and amateur astronomers alike, which gave a very precise trajectory for TC3, including where it would impact.
In December a search began for meteorites, and within days several were found. Spread out over an area 30 kilometers long and about 7 wide, 600 meteorites were eventually found totaling about 11 kilograms.
Then things got weird. The scientists made very careful measurements of which meteorites were found where, and a pattern emerged: Following the trajectory of the asteroid downrange, the pieces that fell the farthest uprange were smaller, while pieces that made it farther downrange were bigger. Not only that, the uprange small pieces from 1 to 50 grams were confined to a narrow path only a kilometer or so wide, but the downrange larger rocks 100 to 400 grams were dispersed farther, some found several kilometers away from the ground path of the incoming asteroid. The pattern looks like a trumpet bell, narrow at one end and wider the farther along you go.
Why?
New research using sophisticated computer modeling of how an asteroid breaks up as it slams into Earths air has provided an answer, and it has to do with the shape of the asteroid and the details of what happens as the huge forces generated by its rapid motion caused it to break up [link to paper].
As the asteroid approached Earth, observations indicated it brightened and dimmed on a regular cycle, indicating it was highly elongated like a Tic Tac or a wide canoe, and rotating very rapidly, once every 49 seconds. As it entered the Earths atmosphere it settled into a single orientation, with its longest dimension ramming through the air (as opposed to narrow end-on like an arrow).
Compressing air that hard heats it up, which in turn heats up the rock on the side facing into the direction of travel. Material started to melt and blow back,a process called ablation. But the asteroid was moving so rapidly it was punching a hole in the air, with a near-vacuum behind it. The small bits of ablated material fell into this vacuum wake, and the high pressure from the shock wave around the main mass of the asteroid kept them there. Still hot, many of the pieces continued to vaporize and shrink, creating smaller particles that were essentially dust.
At the same time the wave of pressure and heating moved through the solid body of the asteroid, dissolving it from front to back. Within seconds it was so eroded it didnt have enough structural strength to withstand the onslaught, and it collapsed. At this point all that was left was material along the backside of the asteroid, which crumbled into large pieces.
The wake vacuum collapsed as well since the asteroid was now gone. The material stuck there was no longer protected and was suddenly exposed to the huge velocity of air moving past it. The small pieces slowed fiercely, eventually falling to the ground not far from the spot over which the final disintegration occurred.
But bigger pieces were more massive and retained their velocity for longer, so they fell farther downrange. That explains why different sizes were found at different locations downrange. But why did the small pieces fall along a narrow path and the big ones were more spread out?
The small ones stayed behind the asteroid for the most part in the wake vacuum, so they fell along that same direction. But when the final collapse occurred all the big pieces suddenly found themselves in open air, and each generated its own strong shock wave of air moving around them. Pieces near each other would feel a violent push away from each other as their individual shock waves interacted, a sideways shove perpendicular to the direction of travel. This gave them some velocity to the side, so when they eventually hit the ground farther downrange they were more spread out.
Most of the meteorites found in this case were therefore from the backside of the asteroid; the material from the front was mostly in the form of dust that trailed behind it to create the train of vaporized material or expanded outward in dust clouds as the asteroid disintegrated.
This may not be the case for every incoming space rock, but this result does help planetary scientists understand the asteroid 2008 TC3 better. For example, the larger rocks that fell to the right of the downward path probably came from the right side of the asteroid, and ones to the left from the asteroids left side. Examining the meteorites showed that some materials were well mixed throughout the asteroid, with no pockets of material preferentially in one place. That gives hints about the history of the asteroid.
The physics of hypervelocity impacts is extremely complex and difficult to model. The success of this model to mimic what happened to 2008 TC3 as it broke apart shows that its possible to learn quite a bit more about these rocks as they come in, and understand better the processes that almost but not necessarily completely destroy them. That in turn means we can better understand the effect they have on the air and ground as they fall. Thats important to know better what kind of damage they can do. Rocks like TC3, a few meters across, hit us a few times a year, and bigger ones are commensurately more rare. But they can do considerable damage just ask the dinosaurs, except you cant for obvious reasons so understanding why and how can have real-world implications for us living at the bottom of Earths ocean of protective air.
Read the original here:
Bad Astronomy | Meteorites from asteroid 2008 TC3 reveal how it broke up | SYFY WIRE - Syfy
- Astronomy clubs want to help you enjoy the eclipse safely - NPR - March 16th, 2024 [March 16th, 2024]
- You Can See a Rare, Bright Comet This Month. Will It Be Visible During the Solar Eclipse? - Smithsonian Magazine - March 16th, 2024 [March 16th, 2024]
- Solar Eclipse Path Map Shows States Where Sun Will Be Blocked Out - Newsweek - March 16th, 2024 [March 16th, 2024]
- Deep-space astronomy sensor peers into the heart of an atom - Space.com - March 16th, 2024 [March 16th, 2024]
- Physics and Astronomy Colloquium - Professor Paul Cassak; Department of Physics and Astronomy, West Virginia ... - The University of Iowa - March 16th, 2024 [March 16th, 2024]
- United Nations prioritizes discussion of Dark and Quiet Skies - Astrobites - March 16th, 2024 [March 16th, 2024]
- The burning acid behind ant stings was spotted around two stars - WAPT Jackson - March 16th, 2024 [March 16th, 2024]
- The oddities known as Centaurs may sprout their tales after jumping to new orbits - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- Pair of astronomy brothers to host eclipse viewing event - KAIT - March 16th, 2024 [March 16th, 2024]
- How to watch the solar eclipse online - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- How does a black hole get to the center of a galaxy, and does the galaxy revolve around it? - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- The eclipse gives astronomy clubs an opportunity to shine - Voice Of Alexandria - March 16th, 2024 [March 16th, 2024]
- AI 'for all': How access to new models is advancing academic research, from astronomy to education - Source - Microsoft - March 16th, 2024 [March 16th, 2024]
- KU Department of Physics & Astronomy professor receives prestigious NSF award for black hole research - Salina Post - March 16th, 2024 [March 16th, 2024]
- Inspect impressive Mare Imbrium Astronomy Now - Astronomy Now Online - March 16th, 2024 [March 16th, 2024]
- The Sky This Week from March 15 to 22: A conjunction of Venus and Saturn - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- Pons-Brooks and M31 - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- The slightly weird mathematical coincidence behind an eclipse - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- APOD: 2024 March 17 NGC 7714: Starburst after Galaxy Collision - Astronomy Picture of the Day - March 16th, 2024 [March 16th, 2024]
- How to Safely View the Eclipse National Radio Astronomy Observatory - National Radio Astronomy Observatory - March 16th, 2024 [March 16th, 2024]
- NOIRLab releases jaw-dropping images, video of remnants from massive star explosion | Astronomy.com - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- JWST spots oceans' worth of water evaporating from a distant disk - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- Radiation is vaporizing a young star's disk in the Orion Nebula - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- APOD: 2024 March 12 A Galaxy Shaped Rocket Exhaust Spiral - Astronomy Picture of the Day - March 16th, 2024 [March 16th, 2024]
- Best laptops for astronomers and astrophotographers in 2024 - Space.com - March 16th, 2024 [March 16th, 2024]
- Why astronomers are worried about 2 major telescopes right now - Space.com - March 16th, 2024 [March 16th, 2024]
- The People Behind Webb | Webb - WebbTelescope.org - March 16th, 2024 [March 16th, 2024]
- X-ray image of universe reveals almost 1 million high-energy objects: 'These are mind-blowing numbers' - Space.com - February 1st, 2024 [February 1st, 2024]
- Galaxy named 'Nube' is almost invisible, baffling astronomers Earth.com - Earth.com - February 1st, 2024 [February 1st, 2024]
- Giant Star Seen 150 Days Before it Exploded as a Supernova - Universe Today - February 1st, 2024 [February 1st, 2024]
- UH astronomer named to prominent national astronomical society | University of Hawaii System News - University of Hawaii - February 1st, 2024 [February 1st, 2024]
- The Art of SeeingStates of Astronomy - Announcements - E-Flux - February 1st, 2024 [February 1st, 2024]
- Pluto isn't really a planet, but it might be Arizona's official state planet - Arizona Mirror - February 1st, 2024 [February 1st, 2024]
- Did You Know? Stars Near and Far Reveal Their Secrets to CSUN Scientists - California State University, Northridge - February 1st, 2024 [February 1st, 2024]
- Top 10 space stories of 2023 - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- How we found the Milky Way's bar: This Week in Astronomy with Dave Eicher - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- The best telescope to use with a smartphone - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- JWST releases 19 awe-inspiring images of spiral galaxies - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- Learning Shines Brightly at SuperKnova National Radio Astronomy Observatory - National Radio Astronomy Observatory - February 1st, 2024 [February 1st, 2024]
- The Crafoord Prize 2024 goes to three ERC grantees for their pioneering contributions to astronomy and mathematics ... - European Research Council - February 1st, 2024 [February 1st, 2024]
- The Moon's south pole is likely not the safest place for manned missions - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- The moon could be perfect for cutting-edge telescopes but not if we don't protect it - Space.com - February 1st, 2024 [February 1st, 2024]
- February Astronomy: Spot the Milky Way and the Zodiacal Light While the Skies Are Darkest - Coachella Valley Independent - February 1st, 2024 [February 1st, 2024]
- You can stream an asteroid whizzing past Earth this weekend - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- Chinese Astronomy at the Royal Observatory | Royal Observatory | Things to do in London - Time Out London - February 1st, 2024 [February 1st, 2024]
- Astronomers in Chile to scour universe with car-sized mega camera - - February 1st, 2024 [February 1st, 2024]
- Dark Matter Might Help Explain How Supermassive Black Holes Can Merge - Universe Today - February 1st, 2024 [February 1st, 2024]
- How far away is the sun? They went on a perilous journey to find out. - National Geographic - February 1st, 2024 [February 1st, 2024]
- Scientists spotted an asteroid hours before it burned up over Germany - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- XRISM Unveils the Invisible: A New Era in X-Ray Astronomy - SciTechDaily - January 10th, 2024 [January 10th, 2024]
- New Astronomy Finding Uncovers the Mystery of Star Formation at the Edge of Galaxies - SBU News - Stony Brook News - January 10th, 2024 [January 10th, 2024]
- The Future Of Astronomy Lies In Artificial Intelligence - Forbes - January 10th, 2024 [January 10th, 2024]
- The 'Super Bowl of Astronomy' begins next week in New Orleans - Space.com - January 10th, 2024 [January 10th, 2024]
- Scientific American proposes policing the language of astronomy to make it beautiful and elegant, as well as ... - Why Evolution Is True - January 10th, 2024 [January 10th, 2024]
- 'Blob-like' home of farthest-known fast radio burst is collection of seven galaxies - Northwestern Now - January 10th, 2024 [January 10th, 2024]
- Astronomers revealed mysterious star formation by hearts of molecular clouds - Tech Explorist - January 10th, 2024 [January 10th, 2024]
- Spectroscopic sizing of interstellar icy grains with JWST - Nature.com - January 10th, 2024 [January 10th, 2024]
- Kip Thorne and the mind-bending science of Interstellar | Astronomy.com - Astronomy Magazine - January 10th, 2024 [January 10th, 2024]
- Here There Be DRAGNs National Radio Astronomy Observatory - National Radio Astronomy Observatory - January 10th, 2024 [January 10th, 2024]
- Unistellar's latest smart telescopes take the hassle out of backyard astronomy - Engadget - January 10th, 2024 [January 10th, 2024]
- 20 of the best places to view the 2024 total solar eclipse - Astronomy Magazine - January 10th, 2024 [January 10th, 2024]
- Northern Arizona astronomy: How old is our third generation sun? - Grand Canyon News - January 10th, 2024 [January 10th, 2024]
- Evidence builds that Kamo'oalewa is a chunk of the Moon accompanying Earth - Astronomy Magazine - January 10th, 2024 [January 10th, 2024]
- The Sky This Week from January 5 to 12: Visitors to the Scorpion - Astronomy Magazine - January 10th, 2024 [January 10th, 2024]
- AAS 243 NRAO Press Announcement - National Radio Astronomy Observatory - January 10th, 2024 [January 10th, 2024]
- Your guide to the sky in 2024 - Astronomy Magazine - January 10th, 2024 [January 10th, 2024]
- The best binoculars for astronomy in 2024 - Popular Science - January 10th, 2024 [January 10th, 2024]
- Are we visible to alien astronomers? This study makes the case - Astronomy Magazine - January 10th, 2024 [January 10th, 2024]
- Mystery of Star Formation Revealed by Hearts of Molecular Clouds - National Radio Astronomy Observatory - January 10th, 2024 [January 10th, 2024]
- Astronomers Solve the Mystery of Giant Radio Circles - AZoQuantum - January 10th, 2024 [January 10th, 2024]
- Early Evolution of Planetary Disk Structures Seen for the First Time - National Radio Astronomy Observatory - January 10th, 2024 [January 10th, 2024]
- XRISM's Revolutionary Insights into X-Ray Astronomy - AZoQuantum - January 10th, 2024 [January 10th, 2024]
- Vatican's chief astronomer talks about stars, beauty, truth - Aleteia - January 10th, 2024 [January 10th, 2024]
- Explore the cosmos in EAC Payson Campus astronomy workshops - Payson Roundup - January 10th, 2024 [January 10th, 2024]
- Neptune is more of a greenish blue than is commonly depicted - NPR - January 10th, 2024 [January 10th, 2024]
- First Yale Gravitational Wave Symposium sparks research innovation | Department of Physics - Yale University - January 10th, 2024 [January 10th, 2024]
- The best expensive telescopes for those ready to splurge - Astronomy Magazine - January 10th, 2024 [January 10th, 2024]
- Dinosaurs and a touch of astronomy | Education | paysonroundup.com - Payson Roundup - January 10th, 2024 [January 10th, 2024]
- Astronomical Illusions: New Images Reveal What Neptune and Uranus Really Look Like - SciTechDaily - January 10th, 2024 [January 10th, 2024]
- Book Review: Things That Go Bump in the Universe, by C. Rene James - The New York Times - December 16th, 2023 [December 16th, 2023]