The discovery of a previously unknown asteroid always begs the question: does the object of our planet? But, as a rule, the initial image gives information only about the brightness and location in the sky, and this is too little for such a forecast. To determine whether the object is in earth, whether it will fly past the Earth or crash into it, it is necessary to know its trajectory, and this requires a series of images obtained over several days or even months.
“We need a number of consecutive frames to calculate the trajectory and to evaluate the risk of collision. But even in this case, the uncertainty can be very high. Less reliable results requires many months of observation,” says Ettore Perozzi from the focal point of the observation of NEOs, ESA in Italy.
19 Oct Katalinski celestial overview (eng. Catalina Sky Survey) recorded an asteroid 2016 WJ1. Over the next few weeks, we received additional pictures taken by observers worldwide and a team of the Observatory of ESA at Canary Islands. This has helped to clarify the trajectory of the asteroid, but not enough to completely eliminate the possibility of him coming to Earth in June 2065 with the probability of collision is approximately 1 in 8,000.
“With these data we searched for in astronomical archives, which could be stored for unidentified images of this object made by someone earlier. In astronomy this is called “predotratit” (precovering),” says Marco Micheli, the observer from the center of ESA.
Research quickly bore fruit: found in online images taken in October by a system of telescopes Pan-STARRS, according to the findings of the team may be imagery of an asteroid.
Although it was only speculation, the researchers used them to find a more reliable image in the finder, Canadian astronomical images astronomical image search system. So, the team managed to identify two sets of images from 4 and 5 July 2003, received by the telescope “Canada-France-Hawaii”.
After careful analysis of the images, the scientists were able to accurately determine the subject and had the opportunity to perform very accurate calculations that showed that the asteroid hardly ever reaches the Earth.