Daily Star (Reino Unido)

Scientists tracking asteroids from another star system as five set to fly past Earth

Publicado em 20 julho 2020

Five huge asteroids are set to fly past Earth at incredible speeds as boffins in Brazil track a further 19 near Jupiter that originated outside our solar system

In a week where NASA revealed five asteroids are expected to make a comparatively close approach to Earth, a Brazilian observatory has release a report identifying 19 nearby space rocks that appear to have come here from another star system entirely.

Scientists at Sao Paulo State University’s Institute of Geosciences and Exact Sciences have identified the interstellar visitors pursuing a bizarre retrograde orbit between Jupiter and Neptune.

The bodies have been classified as centaurs – asteroids that have unstable orbits because they cross or have crossed the orbits of one or more of the giant planets in the outer Solar System.

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They were identified as interstellar immigrants thanks to their unusual path around our solar system, says Maria Helena Moreira Morais, project lead on the report.

One of the bodies is called 514107 Ka’epaoka’awela – a Hawaiian name meaning “tricky” or “mischievous” companion of Jupiter.

Because of its initial astronomical designation 2015 BZ509, Ka’epaoka’awela is also nicknamed “Buzzy.”

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“When we identified it as an object that came from outside the solar system, we didn’t know whether it was an isolated case or part of a vast population of immigrant asteroids,” Morais said. “In this latest study, we recognised 19 Centaurs of interstellar origin.”

Because Buzzy’s orbit is roughly parallel to Jupiter’s, but travelling the “wrong way” around the Sun, the researchers knew it had an unusual origin.

They used a computer simulation they describe as working “like a time machine” to trace Buzzy’s path backwards – showing that some 4.5 billion years ago the little rock was far beyond the edges of our solar system’s disc-shaped structure.

“Our simulation showed that, 4.5 billion years ago, these objects revolved around the sun in orbits perpendicular to the disc’s plane. In addition, they did so in a region distant from the gravitational effects of the original disc,” Professor Morais explained.

The research isn’t just intellectually interesting – “the importance of interstellar matter to the chemical enrichment of the solar system,” Morais says, adding that identifying the might help us find sources of elements that are rare or running out on Earth.

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The five space rocks hurtling toward the Earth have more “ordinary” origins, but they still bear watching. They range from about 50 feet to just under 400 feet in width, and luckily all but one will be giving our planet a fairly wide berth.

The four biggest object will pass by at distances ranging from two to four million miles but the smaller will skim by the Earth at around 48,000 miles, virtually a kiss in astronomical terms.