Science

Earth is safe from Asteroid Apophis for at least next 100 years, says NASA

Hemani Sheth Mumbai | Updated on March 28, 2021

Earth is safe from Asteroid Apophis, a once-feared asteroid that could have posed a risk for at least the next 100 years, US space agency NASA had said.

“The near-Earth object was thought to pose a slight risk of impacting Earth in 2068, but now radar observations have ruled that out,” NASA said in an official release earlier this week.

Apophis was discovered back in 2004. Dubbed asteroid 99942 Apophis which is named after the ancient Egyptian god of chaos and darkness (via BBC), had been identified as one of “the most hazardous asteroids that could impact Earth.”

However, recent assessment have changed the calculations for impact assessment as astronomers tracked Apophis and its orbit became better determined, NASA said.

“A 2068 impact is not in the realm of possibility anymore, and our calculations don’t show any impact risk for at least the next 100 years,” said Davide Farnocchia of NASA’s Center for Near-Earth Object Studies (CNEOS), which is managed by NASA’s Jet Propulsion Laboratory in Southern California.

This is based on the results from a new radar observation campaign combined with “precise orbit analysis.

The asteroid is estimated to be about 1,100 feet (340 meters) across in size.

“Apophis quickly gained notoriety as an asteroid that could pose a serious threat to Earth when astronomers predicted that it would come uncomfortably close in 2029,” NASA said.

Though the risk of an impact in 2029 and the risk posed by another close approach in 2036 has been ruled out, until this month, however, a small chance of impact in 2068 still remained.

The asteroid most recently made a distant flyby of Earth around March 5.

Astronomers leveraged the approach to estimating its orbit around the Sun with high precision and using powerful radar observations. This enabled them to rule out any impact risk in 2068 and long after with confidence.

“With the support of recent optical observations and additional radar observations, the uncertainty in Apophis’ orbit has collapsed from hundreds of kilometres to just a handful of kilometres 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,” said Farnocchia.

The risk list is the Sentry Impact Risk Table maintained by CNEOS. It tracks the “few” asteroids whose orbits can bring them so close to Earth that an impact can’t be ruled out.

“Although Apophis made a recent close approach with Earth, it was still nearly 10.6 million miles [17 million kilometres] away. Even so, we were able to acquire incredibly precise information about its distance to an accuracy of about 150 metres [490 feet],” said JPL scientist Marina Brozovic.

Apophis will pass at a distance of fewer than 20,000 miles (32,000 kilometres) from the earth’s surface on April 13, 2029. During that time, it will be visible to observers on the ground in the Eastern Hemisphere without the aid of a telescope or binoculars.

“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,” read the release.

“When I started working with asteroids after college, Apophis was the poster child for hazardous asteroids,” said Farnocchia. “There’s a certain sense of satisfaction to see it removed from the risk list, and we’re looking forward to the science we might uncover during its close approach in 2029.”

Published on March 28, 2021

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