- 3328 - ASTEROID - Apophis flyby in 2029? After its discovery in 2004, “asteroid 99942”, “Apophis” had been identified as one of the most hazardous asteroids that could impact Earth. But that impact assessment changed as astronomers tracked Apophis and its orbit became better determined
--------------------- 3328 - ASTEROID - Apophis flyby in 2029?
- The results from a new radar observation campaign combined with precise orbit analysis have helped astronomers conclude that there is no risk of Apophis impacting our planet for at least a century.
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- Estimated to be about 1,100 feet across, Apophis quickly gained notoriety as an asteroid that could pose a serious threat to Earth when astronomers first predicted that it would come uncomfortably close in 2029.
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- Thanks to additional observations of the near-Earth object (NEO), the risk of an impact in 2029 was later ruled out, as was the potential impact risk posed by another close approach in 2036. Until this month, however, a small chance of impact in 2068 still remained.
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- When Apophis made a distant flyby of Earth around March 5, astronomers took the opportunity to use powerful radar observations to refine the estimate of its orbit around the Sun with extreme precision, enabling them to confidently rule out any impact risk in 2068 and long after.
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- It zooms safely past Earth on April 13, 2029. Earth’s gravity will slightly deflect the trajectory as the 1,100-foot-wide near-Earth object comes within 20,000 miles of our planet’s surface.
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- With the support of recent optical observations and additional radar observations, the uncertainty in Apophis’ orbit has collapsed from hundreds of kilometers to just a handful of kilometers when projected to 2029. This greatly improved knowledge of its position in 2029 provides more certainty of its future motion, so we can now remove Apophis from the risk list.
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- The “Sentry Impact Risk Table“. Maintained by “CNEOS” keeps tabs on the few asteroids whose orbits take them so close to Earth that an impact can’t be ruled out. With the recent findings, the Risk Table no longer includes Apophis.
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- Relying on optical telescopes and ground-based radar to help characterize every known near-Earth object’s orbit to improve long-term hazard assessments. To arrive at the latest Apophis calculations, astronomers turned to the 70-meter radio antenna at the Deep Space Network’s Goldstone Deep Space Communications Complex near Barstow, California, to precisely track Apophis’ motion.
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- Although Apophis made a recent close approach with Earth, it was still nearly 10.6 million miles away. Astronomers were able to acquire incredibly precise information about its distance to an accuracy of about 150 meters.
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- Goldstone also worked in a collaboration with the 100-meter Green Bank Telescope in West Virginia in order to enable imaging of Apophis; Goldstone was transmitting while Green Bank was receiving a “bistatic” experiment that doubled the strength of the received signal.
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- Although the radar imagery of Apophis appears pixelated, the images have a resolution of 127 feet per pixel. The asteroid was 17 million kilometers away, or about 44 times the Earth-Moon distance. If we had binoculars as powerful as this radar, we would be able to sit in Los Angeles and read a dinner menu at a restaurant in New York.
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- As the radar team further analyzes their data, they also hope to learn more about the asteroid’s shape. Previous radar observations have suggested that Apophis has a “bilobed,” or peanutlike, appearance. This is a relatively common shape among the near-Earth asteroids larger than 660 feet in diameter; at least one in six have two lobes.
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- Astronomers are also working to develop a better understanding of the asteroid’s rotation rate and the axis it spins around . That knowledge will enable them to determine the orientation the asteroid will have with Earth as it encounters our planet’s gravitational field in 2029, which could change that spin state and even cause “asteroid quakes.”
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- On April 13, 2029, the asteroid Apophis will pass less than 20,000 miles from our planet’s surface, closer than the distance of geosynchronous satellites. During that 2029 close approach, Apophis will be visible to observers on the ground in the Eastern Hemisphere without the aid of a telescope or binoculars.
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- It’s also an unprecedented opportunity for astronomers to get a close-up view of a solar system relic that is now just a scientific curiosity and not an immediate hazard to our planet.
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- Apophis was first discovered June 19, 2004 and in December that year NASA gave it a 2.7% chance of hitting Earth. That is a 1 in 37 chance of a big hit. It is 380 yards across, the size of 3 football fields. Many more observations have calculated that Apophis will actually miss Earth speeding by 22,000 miles up.
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- All our geosynchronous, communications satellites are 22,300 miles up. This is 10% the distance to the Moon and less than 3 Earth diameters away. That is a near miss, or a near hit, depending how you look at it.
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- Apophis and know is a stony, metallic meteor weighing more than 100,000 tons. It is traveling 90,000 miles per hour and our atmosphere will not slow it down in the slightest.
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- Typical meteors that we see in the night sky as shooting stars are traveling 70,000 to 140,000 miles per hour. But they routinely weigh less than a gram and quickly burn up in the upper atmosphere.
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- Not all of them. On Marc h26, 2003 a meteor broke apart over Chicago spreading fragments over the ground. If a meteor weighs less than 8 tons our atmosphere will slow it down to 200 to 300 miles per hour before it hit’s the ground. Since 2002 we have recorded seven meteors that have crashed through the roofs of houses.
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- On April 13, 2029 Apophis will pass by 22,000 miles away and visible to the naked eye. It will appear as a magnitude 3 star moving fast across the sky, covering 42 degrees of arc per hour. Earth’s gravity will change its directions , altering its orbit around the Sun. It will be back 7 years later in 2036.
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- We will not know the odds of the next pass until after our 2029 encounter. It currently orbit’s the Sun in 323 days and its path crosses Earth’s orbit twice on each passage around the Sun. It is all a matter of timing to learn if an encounter is to occur.
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- If Apophis does hit it will destroy a surface area the size of Texas. If it hits the oceans it will generate massive tsunamis. Apophis will not be as devastating as the K-T meteor that hit the Yucatan 65 million years ago, but estimates are that a hit would likely kill 50,000,000 people.
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- The impact would be equivalent to 880,000,000 tons of TNT. The Tunguska meteor in Russia was 10,000,000 tons. The 1883 eruption of the Krakatoa volcano was 200,000,000 tons. Talk about high-velocity drama, this should get people’s attention.
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- If you go back 250,000,000 years ago a really big meteor hit the Earth destroying 75% of all land living species and 95% or all ocean dwelling species. This caused the mass extinction to end the Permian geological period in Earth’s history.
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- This meteor instantly transformed the Earth into a cemetery. It was estimated to be an asteroid 30 miles in diameter. The crater is believed to be under the East Antarctic ice sheet, 300 miles in diameter.
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- These craters are being detected on Earth and on the Moon be satellites that experience a slight change in gravity as they pass over head. The slight dips in their orbits enable scientists to map concentrations of mass in the Earth, or the Moon’s crust.
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- When a meteor smashes in to the crust molten rock wells up into a scar. The up welled material is denser than the surrounding crust creating a small increase in the local gravity.
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- The Chicxulub crater in the Yucatan marks the impact that destroyed the dinosaurs 65,000,000 years ago. This meteor was estimated to be 6 miles in diameter.
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- The unsettling idea is that we need to get used to the fact that evolutionary life on Earth saw profound changes from the instantaneous and chance collisions of heavenly bodies with Mother Earth.
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- Some scientists propose that we need to put a transponder on Apophis to more accurately track its orbit. What do you think? Is this a wise use of tax money?
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- November 4, 2021 ASTEROID - Apophis flyby in 2029? 913 3328
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