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Dust Trail
An antitail is an apparent spike projecting from a comet's coma which seems to go towards the Sun, and thus geometrically opposite to the other tails: the ''ion tail'' and the ''dust tail''. However, this phenomenon is an optical illusion that is seen from the Earth. The antitail consists of larger dust particles, which are less affected by the Sun's radiation pressure and tend to remain roughly in the comet's orbital plane and eventually form a disc along the comet's orbit due to the ejection speed of the particles from the comet's surface. As Earth passes through the comet's orbital plane, this disc is seen side on, and appears as the characteristic spike. The other side of the disc can sometimes be seen, though it tends to be lost in the dust tail. The antitail is therefore normally visible for a brief interval only when Earth passes through the comet's orbital plane. Most comets do not develop sufficiently for an antitail to become visible, but notable comets that did disp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C2007N3Lulin2panel Brimacombe
C, or c, is the third letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''cee'' (pronounced ), plural ''cees''. History "C" comes from the same letter as "G". The Semites named it gimel. The sign is possibly adapted from an Egyptian hieroglyph for a staff sling, which may have been the meaning of the name ''gimel''. Another possibility is that it depicted a camel, the Semitic name for which was ''gamal''. Barry B. Powell, a specialist in the history of writing, states "It is hard to imagine how gimel = "camel" can be derived from the picture of a camel (it may show his hump, or his head and neck!)". In the Etruscan language, plosive consonants had no contrastive voicing, so the Greek ' Γ' (Gamma) was adopted into the Etruscan alphabet to represent . Already in the Western Greek alphabet, Gamma first took a '' form in Early Etruscan, then '' in Classical Et ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SPACE
Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime. The concept of space is considered to be of fundamental importance to an understanding of the physical universe. However, disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework. Debates concerning the nature, essence and the mode of existence of space date back to antiquity; namely, to treatises like the ''Timaeus'' of Plato, or Socrates in his reflections on what the Greeks called ''khôra'' (i.e. "space"), or in the ''Physics'' of Aristotle (Book IV, Delta) in the definition of ''topos'' (i.e. place), or in the later "geometrical conception of place" as "spac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C/2022 E3 (ZTF)
C/2022 E3 (ZTF) is a long-period comet from the Oort cloud that was discovered by the Zwicky Transient Facility (ZTF) on 2 March 2022. The comet has a bright green glow around its nucleus, due to the effect of sunlight on diatomic carbon and cyanogen. The comet's systematic designation starts with C to indicate that it is not a periodic comet, and "2022 E3" means that it was the third comet to be discovered in the first half of March 2022. The comet nucleus was estimated to be about a kilometer in size, rotating every 8.5 to 8.7 hours. Its tails of dust and gas extended for millions of kilometers and, during January 2023, an anti-tail was also visible. The comet reached its perihelion on 12 January 2023, at a distance of , and the closest approach to Earth was on 1 February 2023, at a distance of . The comet reached magnitude 5 and was visible with the naked eye under moonless dark skies. Observational history Discovery Astronomers Bryce Bolin and Frank Masci discover ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet PANSTARRS
C/2011 L4 (PanSTARRS), also known as Comet PANSTARRS, is a List of non-periodic comets, non-periodic comet discovered in June 2011 that became visible to the naked eye when it was near perihelion in March 2013. It was discovered using the Pan-STARRS telescope located near the summit of Haleakalā, on the island of Maui in Hawaii. Comet C/2011 L4 probably took millions of years to come from the Oort cloud. After leaving the planetary region of the Solar System, the post-perihelion orbital period (Epoch (astronomy), epoch 2050) is estimated to be roughly Julian year (astronomy), years. Dust and gas production suggests the comet nucleus is roughly in diameter. Observational history Comet C/2011 L4 was still 7.9 Astronomical unit, AU from the Sun with an apparent magnitude of 19 when it was discovered in June 2011. By early May 2012, it had brightened to magnitude 13.5, and could be seen visually when using a large amateur telescope from a dark site. In October 2012, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet Lulin
Comet Lulin (official designation C/2007 N3 (Lulin), Traditional Chinese:鹿林彗星) is a non-periodic comet. It was discovered by Ye Quanzhi and Lin Chi-Sheng from Lulin Observatory. It peaked in brightness and arrived at perigee for observers on Earth on February 24, 2009, at magnitude +5, and at from Earth. The comet was near conjunction with Saturn on February 23, and outward-first headed towards its aphelion, against the present position of background stars, in the direction of Regulus in the constellation of Leo, as noted on February 26 and 27, 2009. It was expected to pass near Comet Cardinal on May 12, 2009. The comet became visible to the naked eye from dark-sky sites around February 7. It figured near the double star Zubenelgenubi on February 6, near Spica on February 15 and 16, near Gamma Virginis on February 19 and near the star cluster M44 on March 5 and 6. It also figured near the planetary nebula NGC 2392 on March 14, and near the double star Wasat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet Hale–Bopp
Comet Hale–Bopp (formally designated C/1995 O1) is a comet that was one of the most widely observed of the 20th century and one of the brightest seen for many decades. Alan Hale and Thomas Bopp discovered Comet Hale–Bopp separately on July 23, 1995, before it became visible to the naked eye. It is difficult to predict the maximum brightness of new comets with any degree of certainty, but Hale–Bopp exceeded most predictions when it passed perihelion on April 1, 1997, reaching about magnitude −1.8. It was visible to the naked eye for a record 18 months, due to its massive nucleus size. This is twice as long as the Great Comet of 1811, the previous record holder. Accordingly, Hale–Bopp was dubbed the great comet of 1997. Discovery The comet was discovered independently on July 23, 1995, by two observers, Alan Hale and Thomas Bopp, both in the United States. Hale had spent many hundreds of hours searching for comets without success, and was tracking ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet Kohoutek
Comet Kohoutek ( formally designated C/1973 E1 and formerly as 1973 XII and 1973f) is a comet that passed close to the Sun towards the end of 1973. Early predictions of the comet's peak brightness suggested that it had the potential to become one of the brightest comets of the 20th century, capturing the attention of the wider public and the press and earning the comet the moniker of "Comet of the Century". Although Kohoutek became rather bright, the comet was ultimately far dimmer than the optimistic projections: its apparent magnitude peaked at only –3 (as opposed to predictions of roughly magnitude –10) and it was visible for only a short period, quickly dimming below naked-eye visibility by the end of January 1974. The comet was discovered by and named after Luboš Kohoutek at the Hamburg Observatory on 18 March 1973; Kohoutek had been searching for Biela's Comet and had fortuitously discovered his eponymous comet while reviewing photographic plates for a differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet Arend–Roland
Comet Arend–Roland was discovered on November 8, 1956 by Belgian astronomers Sylvain Arend and Georges Roland on photographic plates. As the eighth comet found in 1956, it was named Arend–Roland 1956h after its discoverers. Because it was the third comet to pass through perihelion during 1957, it was then renamed 1957 III. Finally, it received the standard IAU designation C/1956 R1 (Arend–Roland), with the "C/" indicating that it was a non-periodic comet and the "R1" showing that it was the first comet reported as discovered in the half-month designated by "R". The last is equivalent to the period September 1–15. Observations In November 1956, a double astrograph at the Uccle Observatory in Brussels was being used for routine investigation of minor planets. On November 8, 1956, the Belgian astronomers Sylvain Arend and Georges Roland discovered a comet on their photographic plates. At that time the comet was at visual magnitude 10, with a strong central condensation and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Plane
The orbital plane of a revolving body is the geometric plane in which its orbit lies. Three non-collinear points in space suffice to determine an orbital plane. A common example would be the positions of the centers of a massive body (host) and of an orbiting celestial body at two different times/points of its orbit. The orbital plane is defined in relation to a reference plane by two parameters: inclination (''i'') and longitude of the ascending node (Ω). By definition, the reference plane for the Solar System is usually considered to be Earth's orbital plane, which defines the ecliptic, the circular path on the celestial sphere that the Sun appears to follow over the course of a year. In other cases, for instance a moon or artificial satellite orbiting another planet, it is convenient to define the inclination of the Moon's orbit as the angle between its orbital plane and the planet's equatorial plane. Artificial satellites around the Earth For launch vehicles and ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-tail
An antitail is an apparent spike projecting from a comet's coma which seems to go towards the Sun, and thus geometrically opposite to the other tails: the ''ion tail'' and the ''dust tail''. However, this phenomenon is an optical illusion that is seen from the Earth. The antitail consists of larger dust particles, which are less affected by the Sun's radiation pressure and tend to remain roughly in the comet's orbital plane and eventually form a disc along the comet's orbit due to the ejection speed of the particles from the comet's surface. As Earth passes through the comet's orbital plane, this disc is seen side on, and appears as the characteristic spike. The other side of the disc can sometimes be seen, though it tends to be lost in the dust tail. The antitail is therefore normally visible for a brief interval only when Earth passes through the comet's orbital plane. Most comets do not develop sufficiently for an antitail to become visible, but notable comets that did di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Radiation Pressure
Radiation pressure is the mechanical pressure exerted upon any surface due to the exchange of momentum between the object and the electromagnetic field. This includes the momentum of light or electromagnetic radiation of any wavelength that is absorbed, reflected, or otherwise emitted (e.g. black-body radiation) by matter on any scale (from macroscopic objects to dust particles to gas molecules). The associated force is called the radiation pressure force, or sometimes just the force of light. The forces generated by radiation pressure are generally too small to be noticed under everyday circumstances; however, they are important in some physical processes and technologies. This particularly includes objects in outer space, where it is usually the main force acting on objects besides gravity, and where the net effect of a tiny force may have a large cumulative effect over long periods of time. For example, had the effects of the Sun's radiation pressure on the spacecraft of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet Dust
Comet dust refers to cosmic dust that originates from a comet. Comet dust can provide clues to comets' origin. When the Earth passes through a comet dust trail, it can produce a meteor shower. Physical characteristics Size The majority of dust from comet activity is sub-micrometer to roughly micrometer in size. However, this fraction is short-lived, as radiation pressure causes them to blow out of the Solar System or spiral inwards. The next size class is large, "fluffy" or "cluster-type" aggregates of the above grains. These are typically 20-100 micrometers, a size not arbitrary but observed as the porous aggregates tend to fracture or compact. Larger particles are micrometeoroids, not dust. "...in practice the term is most often applied to objects smaller than approximately 100 um. These size ranges need to be modified." "By this definition, IDPs are particles smaller than 10um."" In the absence of a definition from the IAU, groups devised their own definitions of dust: small ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
