That Jupiter Trojan comet-like asteroid was neither an asteroid nor a Trojan
Astronomers have now found that the asteroid that had suddenly become active, like a comet, and they had thought was part of the asteroids in Jupiter orbit called Trojans, was neither an asteroid nor a Trojan.
Instead, it is an actual comet captured in a strange unstable orbit around Jupiter.
[W]hen amateur astronomer Sam Deen used software on the Jet Propulsion Laboratory’s solar-system dynamics website to calculate the object’s orbit, he found P/2019 LD2 recently had a close encounter with Jupiter that left its orbit unstable. The model showed that the comet had likely been a Centaur, part of a family of outer solar system asteroids, with an orbit reaching out to Saturn. Then, on February 17, 2017, it passed about 14 million kilometers from Jupiter, an encounter that sent the comet on a wild ride and inserted it into an odd Jupiter-like orbit.
Yet although the swing past Jupiter put P/2019 LD2 into a Jupiter-like orbit, it didn’t move it near to one of the two Lagrange points where the combination of gravitational forces from Jupiter and the Sun hold Trojan asteroids. Instead of being 60° — one-sixth of the giant planet’s orbit — from Jupiter, P/2019 LD2 is only 21° ahead of Jupiter.
The orbit is unstable. It will bring the comet to within 3 million miles of Jupiter in 2063, but beyond that predictions are impossible. The exact closeness of that approach cannot be predicted with much precision, partly because of the chaotic nature of the orbit, and partly because of the random orbital changes that can occur because the comet is venting.
Astronomers have now found that the asteroid that had suddenly become active, like a comet, and they had thought was part of the asteroids in Jupiter orbit called Trojans, was neither an asteroid nor a Trojan.
Instead, it is an actual comet captured in a strange unstable orbit around Jupiter.
[W]hen amateur astronomer Sam Deen used software on the Jet Propulsion Laboratory’s solar-system dynamics website to calculate the object’s orbit, he found P/2019 LD2 recently had a close encounter with Jupiter that left its orbit unstable. The model showed that the comet had likely been a Centaur, part of a family of outer solar system asteroids, with an orbit reaching out to Saturn. Then, on February 17, 2017, it passed about 14 million kilometers from Jupiter, an encounter that sent the comet on a wild ride and inserted it into an odd Jupiter-like orbit.
Yet although the swing past Jupiter put P/2019 LD2 into a Jupiter-like orbit, it didn’t move it near to one of the two Lagrange points where the combination of gravitational forces from Jupiter and the Sun hold Trojan asteroids. Instead of being 60° — one-sixth of the giant planet’s orbit — from Jupiter, P/2019 LD2 is only 21° ahead of Jupiter.
The orbit is unstable. It will bring the comet to within 3 million miles of Jupiter in 2063, but beyond that predictions are impossible. The exact closeness of that approach cannot be predicted with much precision, partly because of the chaotic nature of the orbit, and partly because of the random orbital changes that can occur because the comet is venting.
