2018 LA was initially discovered as a streak traveling quickly across a series of exposures taken with the Mt. Lemmon Survey (part of CSS) telescope in Arizona. This apparent motion in the images revealed its extreme proximity to Earth. Per protocol, 2018 LA data were sent over to the Minor Planet Center, and in turn to NASA’s Scout program of the Center for Near Earth Object Studies ( CNEOS ), which both calculated high probability of the asteroid reaching Earth. In addition, Project Pluto’s Bill Gray calculated an 82 percent chance of impact, with the westernmost possible landing site at the border of South Africa and Botswana. (You can also find 2018 LA’s ephemeris in the Jet Propulsion Laboratory’s Small-Body Database here .)However, these trajectories placed the most likely impact site somewhere in the Indian Ocean, not Africa, leading scientists to question whether the object that lit up the skies was indeed 2018 LA. Follow-up observations of the object from the ATLAS telescope on Maunaloa came in after the event, adding significant information to aid in modeling the asteroid’s path. The ATLAS observations confirmed that the asteroid was bound for impact, and that the fireball (a meteor appearing brighter than the planet Venus) reported in Southern Africa must have been 2018 LA.All of the steps taken in the case of 2018 LA represent standard procedure for most asteroid hunting projects. First comes the discovery, and luckily there are plenty of surveys dedicated to identifying NEOs: in addition to CSS, telescopic surveys such as Pan-STARRS and NEOWISE contribute asteroid findings regularly. For example, the NEOWISE space mission has discovered hundreds of new NEOs since 2013. These NASA funded projects continuously scan the sky for rapidly moving objects like 2018 LA.Once an asteroid has been discovered, scientists want to know its orbital properties as well as its size. This information will help astronomers better classify the object — including whether or not it is a hazard.The size of an asteroid can be tricky to determine. Before they can accurately report a diameter, astronomers must know the asteroid’s magnitude (brightness) and distance, at the very least (usually, they also need an albedo, which measures the reflectivity of an object’s surface). Scientists use a variety of different methods to measure the distance to solar system objects, where precise distance at any given time comes from modeling the asteroid’s path. Knowing its distance and magnitude, astronomers used telescope observations to estimate that 2018 LA was about 2 to 5 m (6.6 to 16.4 ft) across. Luckily, this is not large enough to be hazardous.In the case of 2018 LA, its small size was confirmed using infrasound — sound waves with frequencies below the threshold of human hearing. As 2018 LA burst into pieces, it created infrasound waves equivalent to the explosion of 300-500 tons of TNT. Kowalski states that this explosion was a consequence of the meteor slowing down so rapidly in the atmosphere that its back traveled faster than its front. The resulting signal was picked up by a CTBTO infrasound station in South Africa and corresponded to the expected explosion of a 2-meter (6.6 ft) asteroid.