An asteroid named Bennu was discovered in September of 1999 and it has been fascinating scientists ever since, specifically when and if it will impact our planet. It was previously reported that Bennu has a 1 in 2,700 chance of impacting Earth at some point between the years 2175 and 2199. But new research has revealed a more precise timeline with a slightly greater risk.
Since NASA’s OSIRIS-REx began studying the asteroid at close proximity, scientists have a better understanding of its possible impact on Earth. According to their latest study, Bennu now has a 1 in 1,750 chance of hitting us through the year 2300. While it is a higher risk, scientists say that they’re not worried about an impact.
In a news conference, Davide Farnocchia, who works at NASA's Center for Near Earth Object Studies in California, said, “The impact probability went up just a little bit but it's not a significant change, the impact probability is pretty much the same,” adding, “I think that, overall, the situation has improved.”
On the other hand, they are concerned with the Yarkovsky effect – this is the continuous fluctuations in temperature as parts of Bennu travel in and out of daylight which slightly pushes the asteroid through space. Farnocchia went into further details by explaining, “The Yarkovsky effect acting on Bennu is equivalent to the weight of three grapes.” “That's what's really driving the motion of Bennu into the future, because this acceleration is persistent, its effect builds up over time, and it becomes very significant by the time you get to 2135.”
The year 2135 is significant as scientists are having a difficult time predicting the asteroid’s travel course after that date. What they do know is that Bennu will fly past Earth in September of 2135 but it won’t be close enough for any impact. However, it will be close enough that Earth’s gravity may possibly change the asteroid’s trajectory. Since it’s unclear whether or not our planet’s gravity will affect the asteroid’s trajectory in any way is why scientists can’t fully predict its future travel course after that close fly-by.
Furthermore, there is a concern for September 24, 2182 when Bennu will have a 1 in 2,700 chance of hitting us. At least that’s 161 years away so scientists should have a better understanding of its trajectory and possible impact by then.
The study was published in the journal Icarus where it can be read in full.