The ATLAS telescope first discovered a trojan asteroid with a tail, like a comet. This discovery only confirms the trend of recent years – astronomers find more and more cosmic bodies that first appear to be asteroids, and then develop activity, like in comets, for example, acquiring a tail typical of them. Read more about this at the University of Hawaii.
A warning system for the possible asteroid crash on the Earth of the University of Hawaii (ATLAS) detected such an asteroid among the Jupiter Trojans in June 2019. Checking ATLAS images at Queen’s University in Belfast showed its likely comet character. Subsequent observations by astronomer George Armstrong and his student Sidney Moss using the Las Cumbres observatory global network of telescopes confirmed the cometary nature of this body.
Later, in July 2019, ATLAS again caught 2019 LD2 (the code name for the object) – it really looked like a comet with a faint tail made up of dust or gas. The asteroid passed behind the Sun and was not observed from Earth at the end of 2019 and early 2020, but after its appearance in the night sky in April 2020, ATLAS confirmed that the Trojan still looks like a comet.
The main feature of this object is its orbit. Early signs that it was an asteroid near the orbit of Jupiter were now confirmed by accurate measurements from many different observatories. In fact, 2019 LD2 is a special kind of asteroid that astronomers have not yet discovered.
Trojan asteroids follow the same orbit as the planet but are 60 degrees behind or ahead of the planet. Earth has at least one such Trojan asteroid, and Neptune has dozens. Jupiter has hundreds of thousands. Jupiter’s Trojan asteroids revolve around the Sun in two huge swarms, one swarm rotates ahead of the planet (where 2019 LD2 was found), and the second rotates behind it. Trojan asteroids were captured on these orbits by the strong gravity of Jupiter.
What makes 2019 LD2 so interesting is that astronomers think that most of the Jupiter Trojans were captured billions of years ago. Any ice contained in these asteroids could evaporate, spewing gas and dust, so long ago that objects now resemble asteroids, not comets.
“For decades, we believed that Trojan asteroids should have a large amount of ice beneath their surfaces, but never before had any evidence. ATLAS has shown that predictions of their icy nature may well be correct, ”they said at Queen’s University in Belfast.
According to scientists, Jupiter most likely captured 2019 LD2 recently, which explains its “cometary behavior”.