A meteoroid is a small rocky or metallic body in outer space.
An impact event is a collision between astronomical objects causing measurable effects. Impact events have physical consequences and have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids and have minimal effect. When large objects impact terrestrial planets such as the Earth, there can be significant physical and biospheric consequences, though atmospheres mitigate many surface impacts through atmospheric entry. Impact craters and structures are dominant landforms on many of the Solar System's solid objects and present the strongest empirical evidence for their frequency and scale.
A meteor shower is a celestial event in which a number of meteors are observed to radiate, or originate, from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extremely high speeds on parallel trajectories. Most meteors are smaller than a grain of sand, so almost all of them disintegrate and never hit the Earth's surface. Very intense or unusual meteor showers are known as meteor outbursts and meteor storms, which produce at least 1,000 meteors an hour, most notably from the Leonids. The Meteor Data Centre lists over 900 suspected meteor showers of which about 100 are well established. Several organizations point to viewing opportunities on the Internet. NASA maintains a daily map of active meteor showers.
The Perseids are a prolific meteor shower associated with the comet Swift–Tuttle. The meteors are called the Perseids because the point from which they appear to hail lies in the constellation Perseus.
A bolide is normally taken to mean an exceptionally bright meteor, but the term is subject to more than one definition, according to context. It may refer to any large crater-forming body, or to one that explodes in the atmosphere. It can be a synonym for a fireball, sometimes specific to those with an apparent magnitude of −14 or brighter.
The Kecksburg UFO incident occurred on December 9, 1965, at Kecksburg, Pennsylvania, United States, when a fireball was reported by citizens of six U.S. states and Canada over Detroit, Michigan, and Windsor, Ontario. Astronomers said it was likely to have been a meteor bolide burning up in the atmosphere and descending at a steep angle. NASA released a statement in 2005 reporting that experts had examined fragments from the area and determined they were from a Soviet satellite, but that records of their findings were lost in 1987. NASA responded to court orders and Freedom of Information Act requests to search for the records. The incident gained wide notoriety in popular culture and UFOlogy, with speculation ranging from extraterrestrial craft to debris from the Soviet space probe Kosmos 96, and is often called "Pennsylvania's Roswell".
Green fireballs are a type of unidentified flying object (UFO) that has been reported since the early 1950s. Early sightings primarily occurred in the southwestern United States, particularly in New Mexico. Although some ufologists and ufology organizations consider green fireballs to be of artificial extraterrestrial origin, mainstream, non-pseudoscientific explanations have been provided, including natural bolides.
The Taurids are an annual meteor shower, associated with the comet Encke. The Taurids are actually two separate showers, with a Southern and a Northern component. The Southern Taurids originated from Comet Encke, while the Northern Taurids originated from the asteroid 2004 TG10, possibly a large fragment of Encke due to its similar orbital parameters. They are named after their radiant point in the constellation Taurus, where they are seen to come from in the sky. Because of their occurrence in late October and early November, they are also called Halloween fireballs.
The Great Daylight Fireball was an Earth-grazing fireball that passed within 57 kilometres of Earth's surface at 20:29 UTC on August 10, 1972. It entered Earth's atmosphere at a speed of 15 kilometres per second (9.3 mi/s) in daylight over Utah, United States and passed northwards leaving the atmosphere over Alberta, Canada. It was seen by many people and recorded on film and by space-borne sensors. An eyewitness to the event, located in Missoula, Montana, saw the object pass directly overhead and heard a double sonic boom. The smoke trail lingered in the atmosphere for several minutes.
2008 TC3 (Catalina Sky Survey temporary designation 8TA9D69) was an 80-tonne (80-long-ton; 90-short-ton), 4.1-meter (13 ft) diameter asteroid that entered Earth's atmosphere on October 7, 2008. It exploded at an estimated 37 kilometers (23 mi) above the Nubian Desert in Sudan. Some 600 meteorites, weighing a total of 10.5 kilograms (23.1 lb), were recovered; many of these belonged to a rare type known as ureilites, which contain, among other minerals, nanodiamonds.
A meteor air burst is a type of air burst in which a meteor explodes after entering a planetary body's atmosphere. This fate leads them to be called fireballs or bolides, with the brightest air bursts known as superbolides. Such meteoroids were originally asteroids and comets of a few to several tens of meters in diameter. This separates them from the much smaller and far more common "shooting stars", that usually burn up quickly upon atmospheric entry.
Forensic astronomy is the use of astronomy, the scientific study of celestial objects, to determine the appearance of the sky at specific times in the past. This has been used, if relatively rarely, in forensic science and for resolving historical problems more generally, notably issues in art history.
The 1783 Great Meteor was a meteor procession observed on 18 August 1783 from the British Isles, at a time when such phenomena were not well understood. The meteor was the subject of much discussion in the Philosophical Transactions of the Royal Society and was the subject of a detailed study by Charles Blagden.
The 1913 Great Meteor Procession occurred on February 9, 1913. It was a meteoric phenomenon reported from locations across Canada, the northeastern United States, and Bermuda, and from many ships at sea, including eight off Brazil, giving a total recorded ground track of over 11,000 km. The meteors were particularly unusual in that there was no apparent radiant, the point in the sky from which meteors usually appear to originate. The observations were analysed in detail, later the same year, by the astronomer Clarence Chant, leading him to conclude that as all accounts were positioned along a great circle arc, the source had been a small, short-lived natural satellite of the Earth.
An Earth-grazing fireball is a fireball, a very bright meteor that enters Earth’s atmosphere and leaves again. Some fragments may impact Earth as meteorites, if the meteor starts to break up or explodes in mid-air. These phenomena are then called Earth-grazing meteor processions and bolides. Famous examples of Earth-grazers are the 1972 Great Daylight Fireball and the Meteor Procession of July 20, 1860.
The 1860 Great Meteor procession occurred on July 20, 1860. It was a unique meteoric phenomenon reported from locations across the United States. American landscape painter Frederic Church saw and painted a spectacular string of fireball meteors cross the Catskill evening sky, an extremely rare Earth-grazing meteor procession. It is believed that this was the event referred to in the poem Year of Meteors, 1859-60, by Walt Whitman. In 2010, 150 years later, it was determined to be an Earth-grazing meteor procession.
Gustav Hahn was a German Canadian painter, muralist and interior decorator who pioneered the Art Nouveau style in Canada. Hahn was also an amateur astronomer, and his father, Otto Hahn, owned a collection of meteorites.
On 13 October 1990, meteoroid EN131090, with an estimated mass of 44 kg, entered the Earth's atmosphere above Czechoslovakia and Poland and, after a few seconds, returned to space. Observations of such events are quite rare; this was the second recorded using scientific astronomical instruments and the first recorded from two distant positions, which enabled the calculation of several of its orbital characteristics. The encounter with Earth significantly changed its orbit and, to a smaller extent, some of its physical properties.
2021 GW4 is an Apollo near-Earth object roughly 5 meters (20 feet) in diameter. It was discovered by the Mount Lemmon Survey on 8 April 2021. On 12 April 2021 13:01 UTC it passed 19821 km from the surface of Earth. The uncertainty in the close approach distance was ±30 km.
Donald W. Olson is an astrophysicist and forensic astronomer at the Texas State University. Nicknamed the "Celestial Sleuth," he is known for studying art and history using astronomical data. He is currently regents professor emeritus at Texas State's Department of Physics.
