Aegospotami or Aegospotamos is the ancient Greek name for a small river issuing into the Hellespont, northeast of Sestos.
A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or coma surrounding the nucleus, and sometimes a tail of gas and dust gas blown out from the coma. These phenomena are due to the effects of solar radiation and the outstreaming solar wind plasma acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch beyond one astronomical unit. If sufficiently close and bright, a comet may be seen from Earth without the aid of a telescope and can subtend an arc of up to 30° across the sky. Comets have been observed and recorded since ancient times by many cultures and religions.
Halley's Comet, Comet Halley, or sometimes simply Halley, officially designated 1P/Halley, is a short-period comet visible from Earth every 75–79 years. Halley is the only known short-period comet that is regularly visible to the naked eye from Earth, and thus the only naked-eye comet that can appear twice in a human lifetime. It last appeared in the inner parts of the Solar System in 1986 and will next appear in mid-2061.
Giotto was a European robotic spacecraft mission from the European Space Agency. The spacecraft flew by and studied Halley's Comet and in doing so became the first spacecraft to make close up observations of a comet. On 13 March 1986, the spacecraft succeeded in approaching Halley's nucleus at a distance of 596 kilometers. It was named after the Early Italian Renaissance painter Giotto di Bondone. He had observed Halley's Comet in 1301 and was inspired to depict it as the star of Bethlehem in his painting Adoration of the Magi in the Scrovegni Chapel.
Vega 1 was a Soviet space probe, part of the Vega program. The spacecraft was a development of the earlier Venera craft. They were designed by Babakin Space Centre and constructed as 5VK by Lavochkin at Khimki. The name VeGa (ВеГа) combines the first two letters from the Russian words for Venus and Halley.
The Vega program was a series of Venus missions that also took advantage of the appearance of comet 1P/Halley in 1986. Vega 1 and Vega 2 were uncrewed spacecraft launched in a cooperative effort among the Soviet Union and Austria, Bulgaria, France, Hungary, the German Democratic Republic, Poland, Czechoslovakia, and the Federal Republic of Germany in December 1984. They had a two-part mission to investigate Venus and also flyby Halley's Comet.
Vega 2 was a Soviet space probe part of the Vega program to explore Halley's comet and Venus. The spacecraft was a development of the earlier Venera craft. The name VeGa (ВеГа) combines the first two letters Russian words for Venus and Halley They were designed by Babakin Space Centre and constructed as 5VK by Lavochkin at Khimki. The craft was powered by large twin solar panels. Instruments included an antenna dish, cameras, spectrometer, infrared sounder, magnetometers (MISCHA) and plasma probes. The 4,840 kilograms (10,670 lb) craft was launched on top of a Proton 8K82K rocket from Baikonur Cosmodrome, Tyuratam, Kazakh SSR. Both Vega 1 and 2 were three-axis stabilized spacecraft. The spacecraft were equipped with a dual bumper shield for dust protection from Halley's Comet.
Sakigake, known before launch as MS-T5, was Japan's first interplanetary spacecraft, and the first deep space probe to be launched by any country other than the USA or the Soviet Union. It aimed to demonstrate the performance of the new launch vehicle, test its ability to escape from Earth gravity, and observe the interplanetary medium and magnetic field. Sakigake was also supposed to act as a frame of reference for data received from probes that flew closer to Halley's Comet. Early measurements would be used to improve the mission of the Suisei probe launched several months later.
Suisei, originally known as Planet-A, was an uncrewed space probe developed by the Institute of Space and Astronautical Science.
Astron was a Soviet space telescope launched on 23 March 1983 at 12:45:06 UTC, using the Proton launcher. Based on the 4MV spacecraft design and operational for six years, Astron was the largest ultraviolet space telescope of its time.
The Halley Armada is the name of a series of space probes, five of which were successful, sent to examine Halley's Comet during its 1986 sojourn through the inner Solar System, connected with apparition "1P/1982 U1". The armada included one probe from the European Space Agency, two probes that were joint projects between the Soviet Union and France and two probes from the Institute of Space and Astronautical Science in Japan. Notably, NASA did not contribute a probe to the Halley Armada.
The nucleus is the solid, central part of a comet, once termed a dirty snowball or an icy dirtball. A cometary nucleus is composed of rock, dust, and frozen gases. When heated by the Sun, the gases sublime and produce an atmosphere surrounding the nucleus known as the coma. The force exerted on the coma by the Sun's radiation pressure and solar wind cause an enormous tail to form, which points away from the Sun. A typical comet nucleus has an albedo of 0.04. This is blacker than coal, and may be caused by a covering of dust.
The Adventures of Mark Twain is a 1985 American stop motion claymation fantasy film directed by Will Vinton and starring James Whitmore. It received a limited theatrical release in May 1985. It was released on DVD in January 2006, and again as a collector's edition in 2012 on DVD and Blu-ray.
C/2001 OG108 (LONEOS) is a Halley-type comet with an orbital period of 48.51 years. It was discovered on 28 July 2001 by the LONEOS telescope at Lowell Observatory. Of the short-period comets with known diameters and perihelion inside the orbit of Earth, C/2001 OG108 is the second largest after Comet Swift–Tuttle.
EdmondHalley was an English astronomer, mathematician and physicist. He was the second Astronomer Royal in Britain, succeeding John Flamsteed in 1720.
Werner Landgraf is a German astrophysicist and a discoverer of minor planets.
A great comet is a comet that becomes exceptionally bright. There is no official definition; often the term is attached to comets such as Halley's Comet, which during certain appearances are bright enough to be noticed by casual observers who are not looking for them, and become well known outside the astronomical community. Great comets appear at irregular, unpredictable intervals, on average about once per decade. Although comets are officially named after their discoverers, great comets are sometimes also referred to by the year in which they appeared great, using the formulation "The Great Comet of ...", followed by the year.
Chinese records of comets are the most extensive and accurate in existence from the ancient and medieval periods, and stretch back across three millennia. Records exist at least as far back as 613 BC, and records may have been kept for many centuries before this. There are continuous records all the way through to the nineteenth century, using substantially consistent methods throughout. Chinese data accuracy is unsurpassed in the ancient world and was not overtaken by Western accuracy until the fifteenth century or, in some respects, not until the twentieth century.
