Asteroid 99942 Apophis has been considered one of the most dangerous asteroids with the potential to hit Earth since its discovery in 2004. Now scientists have revised that view after careful analysis of the asteroid’s orbit.
Previous predictions indicated that the 1,110-foot-wide asteroid could be too close for comfort in 2029, 2036, and that it would have a slim chance of hitting Earth in 2068.
During that distant flyby, astronomers used radar observations to better understand the asteroid’s orbit around the sun. Their results allowed them to rule out any risk that the asteroid would hit Earth in 2068. The previous concerns about 2029 and 2036 had already been pushed aside due to sophisticated forecasts and research.
“An impact by 2068 is no longer possible, and our calculations show no impact risk for at least the next 100 years,” said Davide Farnocchia, navigation engineer and researcher at NASA’s Center for Near-Earth Object Studies (CNEOS), in a statement. statement.
“With the support of recent optical observations and additional radar observations, the uncertainty in Apophis’ orbit has decreased from hundreds of miles to just a handful of miles when projected through 2029,” said Farnocchia. “This greatly improved knowledge of his position in 2029 provides more certainty about his future movement, so we can now remove Apophis from the risk list.”
The CNEOS center maintains a risk list and tracks asteroids with orbits that bring them close to Earth – close enough to be concerned about a possible impact. Scientists at the center use radar and telescopes to study objects near Earth and understand the dangers they can pose to the planet.
The CNEOS Center is operated by NASA’s Jet Propulsion Laboratory in Pasadena, California.
To observe and remove Apophis from the risk list, astronomers used the Deep Space Network’s Goldstone radio antenna near Barstow, California. This dish is one of three around the world that allows communication with spacecraft in deep space. Scientists also relied on a partnership with the Green Bank Telescope in West Virginia.
“Although Apophis has approached Earth closely recently, it was still nearly 17.6 million miles away,” Marina Brozovic, a scientist at JPL, said in a statement. “Still, we were able to get incredibly accurate distance information to an accuracy of about 150 meters (490 feet). This campaign helped us not only rule out any impact risk, but also a great scientific opportunity.”
While the images may appear blurry, the resolution is quite strong considering that the asteroid was about 17 million miles away at the time, or 44 times the distance between Earth and the Moon.
“If we had binoculars as powerful as this radar, we could sit in Los Angeles and read a dinner menu at a New York restaurant,” Brozovic said.
The data from this observation will help scientists learn more about the asteroid’s shape and rotational speed. The current belief is that Apophis is in the shape of a peanut.
While Apophis poses no risk for the next century, during its flyby on April 13, 2029, it will encounter Earth’s gravitational field and pass within 32,000 miles of Earth’s surface. That is closer than satellites orbiting the Earth and 10 times closer than the Moon.
Apophis will be visible to humans in the Eastern Hemisphere with the naked eye, no telescope or binoculars needed. And astronomers will have the chance to study the asteroid up close.
“When I started working with asteroids after college, Apophis was the poster child for dangerous asteroids,” said Farnocchia. “It is a certain sense of satisfaction to see it removed from the risk list, and we look forward to the science that we can uncover during the near approach in 2029.”