(More than one asteroid per year may be listed if its size is 100 m or more.) For comparison, the 1908 Tunguska event was caused by an object about 60–190 m (200–620 ft) in size, while the 2013 Chelyabinsk meteor which injured thousands of people and buildings when it generated a large airburst over Russia was estimated to be just 20 m (66 ft) across. objects successfully cataloged on a previous orbit, rather than being detected during final approach.Ī notable case is the relatively large asteroid Duende, which was predicted nearly a year in advance, coincidentally approaching just a few hours after the unrelated Chelyabinsk meteor, which was unpredicted, but injured thousands of people when it impacted.įrom the lists in the first section, these are the largest-known asteroids per year that approach Earth within one LD. Rows highlighted blue indicate objects discovered more than one year before closest approach, i.e. Rows highlighted green indicate objects discovered more than one week before closest approach Rows left white indicate objects discovered 1–7 days before closest approach Rows highlighted yellow indicate objects discovered less than 24 hours before closest approach Rows highlighted red indicate objects which were not discovered until after closest approach comparable to the atomic bombs used in the Second World War. Of the objects so detected, 78 had an impact energy greater than that of a 1-kiloton device (equivalent to 1000 tons of TNT), including 11 which had an impact energy greater than that of a 10-kiloton device i.e. This list does not include any of the hundreds of objects that collided with Earth, which were not discovered in advance, but were recorded by sensors designed to detect detonation of nuclear devices. 2018 has fared better so far, with six out of the eight known close encounters being detected beforehand, albeit with less than 24 hours' notice in most cases. Of these, eight were undetected until after they'd happened and only one was detected with more than 24 hours' notice. The table shows that the years 20 had a total of 13 such close encounters that are known. ![]() For comparison, since a satellite in a geostationary orbit has an altitude of about 36,000 km (22,000 mi), then its geocentric distance is 0.11 LD (approximately three times the width of the Earth). More than one asteroid per year may be listed if its geocentric distance is within a tenth of the lunar distance, or 0.10 LD. Lucy draws its name from Lucy, the fossilized Australopithecus afarensis - and human ancestor - discovered in 1974 (Lucy the skeleton was named after the Beatles song, “Lucy in the sky with diamonds”).From the list in the first section, these are the closest-known asteroids per year that approach Earth within one lunar distance. The Jupiter Trojans are believed to date to the very earliest days of the Solar System, fossilized remnants from more than 4 billion years ago. The Trojan asteroid Queta - discovered in 2020 and named for Mexican track and field athlete Norma Enriqueta “Queta” Basilio Sotelo - was the first to be named under this convention. This spurred the decision to name smaller Trojan asteroids after Olympic and Paralympic athletes. However, recently the International Astronomical Union realized there were more Trojan asteroids than names in The Illiad. Trojan came to refer to any asteroid that shares an orbit with a planet, for instance, the Neptunian Trojans discovered in 2006. The term “Trojan” stems from the initial decision to name the L4 asteroids after the Greek soldiers in The Illiad and L5 asteroids after the Trojan warriors in the epic poem about the ancient Trojan War. ![]() NASAįirst discovered in 1906, the astronomers have now identified more than 4,800 Jupiter Trojan asteroids. An artists rendering of the Trojan Asteroids near Jupiter.
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