Astronomers say they will have to keep an eye on them asteroid near Earth Apophis to see how dangerous a space rock is to our planet on a close pass in 2068. But don’t panic: The likelihood of a collision appears to still be very low.
In certain cases, the sun can unevenly heat an asteroid, causing space rock to radiate asymmetrically. The result can be a small repulsion in a certain direction – an effect known as the Yarkovsky acceleration, which can change the path of a small planet through space.
Since astronomers have not measured this solar repulsion on Apophis before, they did not take it into account when calculating the threat the asteroid poses to us in 2068. Previous calculations indicated very small collision probability ̵1; about 1 in 150,000.
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Now, a new study shows that the asteroid is drifting out of orbit previously predicted about 557 feet (170 meters) a year due to the Yarkovsky effect, lead author and astronomer David Tholen of the University of Hawaii. in Manoa said during the press conference on October. 26.
“Essentially, the heat an asteroid radiates gives it a very small thrust,” he explained during the virtual meeting of the Planetary Science Department of the American Astronomical Association. You can find press conference on YouTube here. It starts at 22 minutes.
“The hemisphere is warmer [of the asteroid] Tholen says it will push a little more than the colder hemisphere, and that makes the asteroid float out of a completely gravitational orbit.
When he pointed out that Apophis’ orbit was 1,120 feet (340 m) wide, he pointed out that astronomers thought they had observed enough asteroids – collected in the years after its discovery in 2004. – to more or less rule out an impact by 2068. However, those calculations are based on the orbit that is not affected by the solar energy. Ultimately, this means we still can’t rule out Apophis as a threat by 2068, Tholen said.
“The 2068 impact scenario is still going on,” Tholen said. “We need to monitor this asteroid very carefully.”
Fortunately, the asteroid will get close (but still safe) to our planet by 2029, allowing terrestrial telescopes – including Arecibo Observatory’s powerful radar disc – Get a more detailed view of the asteroid’s surface and shape. Apophis will be so close it will be visible to the naked eye, at a third magnitude – as bright as Cor Caroli binary star.
“In all days, Friday, April 13, April 13 That’s when the fly-fly phenomenon happens, ”said Tholen.“ Obviously, the near-2029 approach is critical. We’ll know after exactly where that happens [Apophis] like when it passed through the Earth and that would help us predict future impact scenarios much easier. “
Tholen’s team discovered after four nights of observations in January and March with the Subaru Telescope, a Japanese optical-infrared telescope atop Maunakea, Hawaii. The researchers collected 18 exposures of the asteroid with great precision, with an error of only 10 milliseconds per observation. (A millisecond is one-thousandth of an arc second, a measurement of the angle Help scientists measure cosmic distances.)
“We really nailed the asteroid’s position very well,” Tholen said. “That’s enough for us to find out The Yarkovsky effectThat is something we’ve been expecting to see for a while. “
Tholen notes that Apophis has troubled astronomers, with “multiple impact scenarios” predicted (and then largely excluded) since it was first found in 2004. The wallet For example: Scientists initially calculated a 3% chance of Apophis crashing our planet in the Year 2029, a prediction Tholen said was quickly ruled out after more observations showed the path. really small world.
If there is any threat of impact, astronomers will know long before 2068 how to approach the problem. Engineers around the world are developing ideas for how to deflect dangerous asteroids From our planet, concepts ranging from gravitational pull to “kinetic action” can deflect a rock to deviate.
A joint NASA-Europe mission will also test and observe the asteroid deflection at a space rock called Didymos, starting in 2022. If all goes according to plan, NASA’s Double Asteroid Redirection Test (DART) the spacecraft will plunge into “Didymoon”, the moon orbiting Didymos. The European Space Agency will then launch the Hera mission in 2023 or 2024 and arrive at Didymos two years later, to see how well the kinetic impact has done in moving the moon from the previous orbit. its.
NASA has one Planetary Defense Coordination Office collect asteroid observations from a network of partner telescopes and run through scenarios with other US agencies about asteroid deflection or (worst case scenario) Evacuate threatened populations from an incoming space rock. Until now, decades of observations have found no imminent threat to asteroids or comets to our planet.
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