Comets visit the inner Solar System, and leave without saying goodbye. Maybe they leave a trail of dust behind, and when the Earth passes through it, we get a pretty light show in the night sky, in the form of a meteor shower. Likewise, asteroids frequently go whizzing by, though they don’t leave us with a pyrotechnic display.
Sometimes these rocky interlopers head straight for Earth. And when they do, the results can be cataclysmic, like when an asteroid struck Earth about 66 million years ago, wiping out the dinosaurs and 75% of life on Earth. Other times, it’s not quite as cataclysmic, but still devastating, like in about 2350 BC, when debris from a disintegrating comet may have caused the collapse of an ancient empire.
But regardless of the severity of any of these individual events, the conclusion is crystal clear: Earth’s history is intertwined with the coming and going of space rocks. The evidence is all around us, sort of.
Continue reading “Ancient Meteorites Can be Found Embedded in Rocks, Like Fossils”
Before our Solar System had planets, it had planetesimals. Scientists think that most of the meteorites that have struck Earth are fragments of these planetesimals. Scientists also think that these planetesimals either melted completely, very early in their history, or that they remained as little more than collections of rocks, or “rubble piles.”
But one family of meteorites, that have been found spread around the world, appear to come from a planetesimal that bucked that trend.
Continue reading “A Group of Meteorites All Came From a Destroyed Planetesimal With a Magnetic Core”
What are your chances of getting smacked – and killed — by a meteorite? One astronomer put the odds of death by space rock at 1 in 700,000 in a lifetime, while others say it’s more like 1 in 1,600,000.
Computing the probability for such an untimely death is difficult because this type of event is so rare. In fact, even though thousands of meteorites are thought to hit the ground each year, in looking through the annals of meteorite history, there seemed to be no evidence that anyone had ever been killed by a meteorite. Until now.
Continue reading “Terrible Luck. The Only Person Ever Killed by a Meteorite – Back in 1888”
20% of the surface of Earth’s Eastern Hemisphere is littered with a certain kind of rock. Black, glossy blobs called tektites are spread throughout Australasia. Scientists know they’re from a meteorite strike, but they’ve never been able to locate the crater where it struck Earth.
Now a team of scientists seems to have found it.
Continue reading “Almost 800,000 Years Ago, an Enormous Meteorite Struck Earth. Now We Know Where.”
About 466 million years ago, there was an asteroid collision in the asteroid belt between Mars and Jupiter. The collision caused the breakup of a major asteroid, creating a shower of dust throughout the inner Solar System. That event is called the Ordovician Meteor Event, and its dust caused an ice age here on Earth.
That ice age contributed to an enormous boost in biodiversity on ancient Earth.
Continue reading “A Distant Asteroid Collision Gave Earthly Biodiversity An Ancient Boost”
Remember the asteroid Psyche? It’s the largest known asteroid in the asteroid belt between Mars and Jupiter. It’s been in the news because of its unusual properties, and because NASA plans to launch a mission to Psyche in 2022.
Psyche, aka 16 Psyche, is unusual because it’s quite different from other asteroids. Psyche appears to be the remnant, exposed nickel-iron core of an early planet. Because of that, Psyche is a building block left over from the early Solar System, when planets were still forming. It’s like a planet without a crust.
Continue reading “Metallic Asteroids Might Have Had Volcanoes Erupting Molten Iron. That’s So Metal”
On Wednesday, July 24th, the people of the Great Lakes region were treated to a spectacular sight when a meteor streaked across the sky. The resulting fireball was observed by many onlookers, as well as the University of Western Ontario’s All-Sky Camera Network. This array runs across southern Ontario and Quebec and is maintained in collaboration with NASA’s Meteoroid Environment Office (MEO) at the Marshall Space Flight Center.
What is especially exciting about this event is the possibility that fragments of this meteorite fell to Earth and could be retrieved. This was the conclusion reached by Steven Ehlert at the MEO after he analyzed the video of the meteorite erupting like a fireball in the night sky. Examination of these fragments could tell astronomers a great deal about the formation and evolution of the Solar System.
Continue reading “Bright Fireball Explodes Over Ontario, Meteorite Fragments Might Have Reached the Ground”
Since it first formed roughly 4.5 billion years ago, planet Earth has been subject to impacts by asteroids and plenty of meteors. These impacts have played a significant role in the geological history of our planet and even played a role in species evolution. And while meteors come in many shapes and sizes, scientists have found that many become cone-shaped once they enter our atmosphere.
The reason for this has remained a mystery for some time. But thanks to a recent study conducted by a team of researchers from New York University’s Applied Mathematics Lab have figured out the physics that leads to this transformation. In essence, the process involves melting and erosion that ultimately turns meteorities into the ideal shape as they hurl through the atmosphere.
Continue reading “As Meteorites Slice Through the Atmosphere, They’re Sculpted Into Cones”
When an extraterrestrial object slams into the Earth, it sends molten rock high into the atmosphere. That debris cools and re-crystallizes and falls back down to Earth. Tiny glass beads that form in this process are called microtektites, and researchers in Florida have found microtektites inside fossilized clams.
Continue reading “Fossilized Clams Had Evidence of a Meteorite Impact Inside Them”
The early days of the Solar System are hard to piece together from our vantage point, billions of years after it happened. Now a team of scientists have found a tiny chunk of an ancient comet inside an ancient meteorite. They say it sheds light on the early days of the Solar System when planets were still forming.
Continue reading “Astronomers Find a Chunk of a Comet Inside a Meteorite”