A study published in November proposes that loosely bound, clumpy asteroids with curveball-like spins may have shaped unique Earth craters, including Arizona's Barringer Crater.
The research, titled "Impact craters formed by spinning granular projectiles" published in Physical Review E, suggests that craters from fast-spinning asteroids are wider and shallower, contrary to expectations.
Asteroid Spin and Cohesion Shape Impact Sites
When space rocks hit Earth, they create an impact crater that exhibits different shapes. An example of an impact crater on the planet is Arizona's Barringer Crater, which looks like a bowl. Geologists previously linked crater diversity to factors like impact velocity.
In a recent study, researchers focused on overlooked parameters, including an asteroid's spin and the possibility of clumpy structures in incoming impactors, challenging traditional notions about crater formation.
Erick Franklin, a researcher at Brazil's University of Campinas and co-author of the study, emphasizes that investigating asteroid rotation and cohesion offers valuable insights into the formation of various types of craters and the dispersion of impactor material post-collision.
In their investigation, researchers conducted numerous simulations using virtual asteroid-like projectiles, each equivalent to the size of a grapefruit and composed of two thousand mite-sized spheres. The spin of these virtual asteroids varied from a super slow-spin splitter to an off-the-charts high-spin curveball.
The study's findings revealed that tightly bound, rapidly rotating asteroids tended to create narrow, deep craters. In contrast, fast-spinning "rubble piles" such as Bennu, with weakly bound components, resulted in wide, shallow craters.
Franklin explained that the dispersion of grains forming the projectile at impact influenced the crater's depth and width, with a greater radial spread leading to shallower and wider craters. This is attributed to the energy used in breaking the bonds between the components, scattering fragments with less energy, resulting in less penetration into the ground compared to non-rotating asteroids.
The implications extend beyond theoretical understanding, pointing to potential real-world examples, such as Barringer Crater and Flynn Creek Crater in Tennessee, both potentially shaped by the unique dynamics of rapidly rotating asteroids.
This study challenges conventional notions about the role of spin and cohesion in shaping impact craters, offering a nuanced perspective on the complex processes governing celestial encounters with Earth.
Largest Impact Craters on Earth
Discovering signs of Earth's historical encounters with asteroids, comets, and meteorites can often be found in plain view, providing hidden evidence of past bombardment. Here are the five largest craters on Earth ever recorded:
Vredefort Crater - South Africa (27°0′S 27°30′E)
- Formed 2.02 billion years ago, the largest and oldest Earth impact crater boasts a diameter of 185 miles (300 km) and features multiple rings, resembling the Valhalla Crater on Jupiter's moon Callisto.
Chicxulub Crater - Mexico (21°20′N 89°30′W)
- Unearthed in 1978 through a magnetic survey over the Yucatán Peninsula, this crater, with a diameter of 110 miles (180 km), is associated with the extinction event of dinosaurs 66 million years ago caused by an asteroid measuring 6.2 miles (10 km) in diameter.
Sudbury Crater - Ontario, Canada (46°36′N 81°11′W)
- Formed 1.85 billion years ago, this crater, initially spanning 160 miles (260 km), resulted from a comet impact, conclusively determined in 2014, with scattered debris discovered more than 500 miles (800 km) away in Minnesota.
Popigai Crater - Russia (71°39′N 111°11′E)
- Created 35 million years ago by a 5-mile-wide (8 km) stony asteroid, this 62-mile-wide (100 km) crater, containing diamonds formed from graphite, remained off-limits until 1997 due to the precious mineral's presence.
Manicouagan Crater - Quebec, Canada (51°23′N 68°42′W)
- Formed 214 million years ago by a 3-mile-wide (5 km) meteorite, this 60-mile-wide (100 km) multiple-ring crater is part of a potential multiple impact event, contributing to a chain of craters.
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