- 2967 - METEORS - impacts early Earth and today? Our Solar System has an asteroid belt with thousands of asteroids orbiting between the orbits of Mars and Jupiter. When did these asteroids get here? How did they get here? Is this belt the only source of the meteors and meteorites we frequently encounter colliding with Earth?
----------------------- 2967 - METEORS - impacts early Earth and today?
- Researchers were able to use magnetism to determine when some carbonaceous chondrite asteroids, which are asteroids that are rich in water and amino acids, first arrived in the inner solar system.
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- They were able to learn about the early origins of the solar system and why some planets, such as Earth, became habitable and were able to sustain conditions conducive for life, while other planets, such as Mars, did not.
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- This same research can be applied to help in the discovery of new exoplanets. There have been over 4,000 exoplanet discoveries to date. But, how are we to deduce whether events might have been similar or different in all of these exo-solar systems?
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- Some meteorites are just pieces of debris from asteroids. After breaking apart from their "parent bodies," these pieces are able to survive passing through the atmosphere and eventually hit the surface of a planet or moon.
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- Studying the magnetization of these meteorites can give researchers a better idea of when the objects formed and where they were located early in the solar system's history. Astronomers can use the magnetism of meteorites derived from asteroids to determine how far these meteorites were from the sun when their magnetic minerals formed.
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- This magnetic data was collected from the “Allende meteorite“, which fell to Earth and landed in Mexico in 1969. The Allende meteorite is the largest carbonaceous chondrite meteorite found on Earth and contains minerals which are calcium-aluminum inclusions, and are thought to be the first solids formed in the solar system.
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- A paradox about meteorites that was confounding the scientific community is how did the meteorites gain magnetization? Some researchers have proposed that carbonaceous chondrite meteorites like Allende had been magnetized by a core dynamo, like that in the core of Earth.
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- Earth is known as a “differentiated body” because it has a crust, mantle, and core that are separated by composition and density. Early in their history, planetary bodies can gain enough heat so that there is widespread melting and the dense material, iron, sinks to the center. Then layers of mantel are distributed according to the mass of each of the materials.
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- Computer simulations showed that it was solar winds draped around early solar system bodies that magnetized these bodies. Using simulations the researchers determined that the parent asteroids from which carbonaceous chondrite meteorites broke off arrived in the Asteroid Belt from the outer solar system about 4,562 million years ago, within the first 5 million years of solar system history.
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- This analyses and modeling offers more support for the so-called “grand tack theory” of the motion of Jupiter. While scientists once thought planets and other planetary bodies formed from dust and gas in an orderly distance from the sun, today scientists realize that the gravitational forces associated with giant planets, Jupiter and Saturn, can drive the formation and migration of planetary bodies and asteroids.
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- The grand tack theory suggests that asteroids were separated by the gravitational forces of the giant planet Jupiter, whose subsequent migration then mixed the two asteroid groups. This early motion of carbonaceous chondrite asteroids sets the stage for further scattering of water-rich bodies later in the development of the solar system, and it may be a pattern common to exoplanet systems.
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- There was an asteroid blast was the second largest of its kind in 30 years, and the biggest since the fireball over Chelyabinsk in Russia six years ago. But it went largely unnoticed until now because it blew up over the Bering Sea, off Russia's Kamchatka Peninsula. The space rock exploded with 10 times the energy released by the Hiroshima atomic bomb.
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- A fireball this big is only expected about two or three times every 100 years. At about noon local time on December 18, the asteroid barreled through the atmosphere at a speed of 32km/s (20 miles per second) , on a steep trajectory of seven degrees.
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- Measuring several meters in size, the space rock exploded 25.6 kilometers above the Earth's surface, with an impact energy of 173 kilotons. That was 40% the energy release of Chelyabinsk, but it was over the Bering Sea so it didn't have the same type of effect or show up in the news.
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- In 2005, Congress tasked Nasa with finding 90% of near-Earth asteroids of 140m (460ft) in size or larger by 2020. Space rocks of this size are so-called "problems without passports" because they are expected to affect whole regions if they collide with Earth. But scientists estimate it will take them another 30 years to fulfill this congressional directive.
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- Once an incoming object is identified, NASA has had some notable success at calculating where on Earth the impact will occur, based on a precise determination of its orbit. In June 2018, the small 3m (10ft) asteroid “2018 LA” was discovered by a ground-based observatory in Arizona eight hours before impact.
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- The “Center for Near-Earth Object Studies” at Nasa's Jet Propulsion Laboratory (JPL) then made a precision determination of its orbit, which was used to calculate a probable impact location. This showed the rock was likely to hit southern Africa.
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- Just as the calculation suggested, a fireball was recorded over Botswana by security camera footage on a farm. Fragments of the object were later found in the area.
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- The event over the Bering Sea shows that larger objects can collide with us without warning, underlining the need for enhanced monitoring. A more robust network would be dependent not only on ground telescopes, but space-based observatories also.
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- A mission concept in development would see a telescope called NeoCam launched to a gravitational balance point in space, where it would discover and characterize potentially hazardous asteroids larger than 140m.
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- The idea is really to get as close as possible to reaching that 90% goal of finding the 140m and larger near-Earth asteroids given to NASA by Congress.
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.---------------------------- Other reviews available about meteors:
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- 2756 - METEOR - Chicxulup Mexico meteor? Impact-generated hydrothermal systems were prominent features on early Earth and wherever water exists in a planetary crust. This model is transferable to an early Mars and any exoplanetary system with similar conditions. Maybe we should be looking for exoplanets with ancient impact craters if we want to find life.
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- 2633 - METEORS - we call them shooting stars. How four small pieces of rock can teach us about the history of the solar system. The first is a meteor from outer space that hurtled through the atmosphere of a bright, blue planet to land upon a world populated by strange, multi-tentacle creatures.
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- 2586 METEORITE - the oldest meteorite? A meteorite that crashed into rural southeastern Australia in a fireball in 1969 contained the oldest material ever found on Earth, stardust that predated the formation of our solar system by billions of years
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- 2389 - METEORS - we call them shooting stars. Shooting Stars are meteoroids that enter Earth’s atmosphere in the night sky. On average on a dark night you can see a shooting star once an hour. These meteoroids are rocky dust and debris zipping around our solar system at 30,000 mph.
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- 2343- The Story of a Rock A meteorite rock was found in Oman, Africa in September, 2002. The rock tells us that it came from the Moon and it even tells us which crater on the Moon it was ejected from. About 30 Earth rocks have been found and identified as originating on the Moon. This is the story of two of these rocks. The first rock was found in Oman. a country southeast of Saudi, Arabia on the Arabian Peninsula.
1619 - How often do meteors hit Earth and how big are they? What were the more famous meteors that impacted Earth. What is the likelihood another big one is on its way?
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- 1611 - Meteor Impacts. How many meteors of all types hit us each year? When is the next big hit expected? Learn the equations that give the answers.
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- 1567 - The Russian Meteor - The Russian Meteor. Valentine’s Day was a real surprise for many people in Russia. February 14, 2013, a 10,000 ton meteor blasted through the atmosphere. The fireball was traveling 40,000 miles per hour. The shockwave created when the meteor hit the atmosphere blew out glass windows in over 3,000 buildings, over a 1,000 square kilometers.
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- Over 1,000 people were injured. Mostly glass cuts, one with a broken back. People instinctively went to the windows to see what caused the giant flash of light. They were standing in front of the windows when the shockwave reached them.
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- 1557 - Tektites in Healdsburg, California - January 23, 2013, our local paper ran an article about the tektites found in Dry Creek Valley around Healdsburg, California, just 20 miles from my house. What in the world are tektites?
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- 1019 - The Sudbury Asteroid. A giant asteroid struck Earth 1,850,000,000 years ago creating the Sudbury Basin in Ontario, Canada. The impact blew a crater in the shallow sea floor that was 160 miles across. Along the seashore were dense colonies of cyan bacteria. Their stumpy masses are call stromatolites
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- 1017 - Meteorite and Asteroids. Meteorites have been landing on the surface of Earth for millions of years. We have found many of them. You can buy them on E-Bay. In 2004 in Placid, Florida a 5.3 pound asteroid was recovered. E-bay says it came from the planet Mercury so it would yield a higher price. But, astronomers do not think it came from Mercury. They believe it came from the Asteroid Belt.
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- 719 - Geminid Meteor Shower.
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- 523 - The Story of a Rock
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January 8, 2021 METEORS - impacts early Earth and today? 2967
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