Coma (cometary)
The coma is the nebulous envelope around the nucleus of a comet. It is formed when the comet passes close to the Sun on its highly elliptical orbit; as the comet warms, parts of it sublimate. This gives a comet a "fuzzy" appearance when viewed in telescopes and distinguishes it from stars. The word coma comes from the Greek "kome" (κόμη), which means "hair" and is the origin of the word comet itself.
The coma is generally made of ice and comet dust. Water dominates up to 90% of the volatiles that outflow from the nucleus when the comet is within 3-4 AU of the Sun. The H2O parent molecule is destroyed primarily through photodissociation and to a much smaller extent photoionization. The solar wind plays a minor role in the destruction of water compared to photochemistry. Larger dust particles are left along the comet's orbital path while smaller particles are pushed away from the Sun into the comet's tail by light pressure.
On 11 August 2014, astronomers released studies, using the Atacama Large Millimeter/Submillimeter Array (ALMA) for the first time, that detailed the distribution of HCN, HNC, H2CO, and dust inside the comae of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON). On 2 June 2015, NASA reported that the ALICE spectrograph on the Rosetta space probe studying comet 67P/Churyumov–Gerasimenko determined that electrons (within 1 km (0.62 mi) above the comet nucleus) produced from photoionization of water molecules by solar radiation, and not photons from the Sun as thought earlier, are responsible for the degradation of water and carbon dioxide molecules released from the comet nucleus into its coma.
Coma (optics)
In optics (especially telescopes), the coma, or comatic aberration, in an optical system refers to aberration inherent to certain optical designs or due to imperfection in the lens or other components that results in off-axis point sources such as stars appearing distorted, appearing to have a tail (coma) like a comet. Specifically, coma is defined as a variation in magnification over the entrance pupil. In refractive or diffractive optical systems, especially those imaging a wide spectral range, coma can be a function of wavelength, in which case it is a form of chromatic aberration.
Coma is an inherent property of telescopes using parabolic mirrors. Unlike a spherical mirror, a bundle of parallel rays parallel to the optical axis will be perfectly focused to a point (the mirror is free of spherical aberration), no matter where they strike the mirror. However, this is only true if the rays are parallel to the axis of the parabola. When the incoming rays strike the mirror at an angle, individual rays are not reflected to the same point. When looking at a point that is not perfectly aligned with the optical axis, some of the incoming light from that point will strike the mirror at an angle. This results in an image that is not in the center of the field looking wedge-shaped. The further off-axis (or the greater the angle subtended by the point with the optical axis), the worse this effect is. This causes stars to appear to have a cometary coma, hence the name.
Coma (Pendulum song)
"Coma" is the third single by Australian ambient house band Pendulum. The single was released in July 1997 and peaked at #46 on the ARIA Singles Chart spending just 2 weeks on the Chart. It was later included on the album 3 Knocks and Triple J Hottest 100, 1997, where it ranked #32. It was the final single release from the band as they split in early 1998.
References
Black
Black is the darkest color, the result of the absence of or complete absorption of light. It is the opposite of white (the combined spectrum of color or light). It is an achromatic color, literally a color without color or hue. It is one of the four primary colors in the CMYK color model, along with cyan, yellow, and magenta, used in color printing to produce all the other colors.
Black was one of the first colors used by artists in neolithic cave paintings. In the 14th century, it began to be worn by royalty, the clergy, judges and government officials in much of Europe. It became the color worn by English romantic poets, businessmen and statesmen in the 19th century, and a high fashion color in the 20th century.
In the Roman Empire, it became the color of mourning, and over the centuries it was frequently associated with death, evil, witches and magic. According to surveys in Europe and North America, it is the color most commonly associated with mourning, the end, secrets, magic, force, violence, evil, and elegance.
White and Black in chess
In chess, the player who moves first is referred to as "White" and the player who moves second is referred to as "Black". Similarly, the pieces that each conducts are called, respectively, "the white pieces" and "the black pieces". The pieces are often not literally white and black, but some other colors (usually a light color and a dark color, respectively). The 64 squares of the chessboard, which is colored in a checkered pattern, are likewise referred to as "white squares" or "light squares" on the one hand, and "black squares" or "dark squares" on the other. In most cases, the squares are not actually white and black, but a light color and a contrasting dark color. For example, the squares on plastic boards are often off-white ("buff") and green, while those on wood boards are often light brown and dark brown.
In old chess writings, the sides are often called Red and Black, because those were the two colors of ink then commonly available when hand-drawing or printing chess position diagrams.
Black (2004 film)
Black: The Man From Darkness is a 2004 Indian Malayalam crime thriller film written and directed by Ranjith, and produced by Lal. It deals with the underworld operations in Kochi. Mammootty plays the role of Police Constable Karikkamuri Shanmugham, who ironically is a hit man and a contract killer. The film features cinematography by Amal Neerad. The film was a comeback for actor Rahman to Malayalam cinema. The film was a box office hit.
Plot
Black is based on the underground activities in the city of Kochi(Cochin). Shanmughan (Mammooty) plays a Head Police Constable but also a hitman who does his job with perfection. On the top of the underworld, there is a man, Advocate Devin Carlos Padaveedan (Lal). He and Shanmughan are accomplices.
A newly appointed police officer, Ashok (Rahman), tries to clean up the city from the criminals, but fails to do so as he is killed by Padaveedan. Shanmugan is not very happy about the death of Ashok, and creates some indifference between the friends. After Shanmugan finds his own daughter, he wants to live a peaceful life, but the transformation is not acceptable to Padaveedan, and he wants Shanmughan dead.
Silentó
Richard Lamar Hawk (born January 22, 1998), better known by his stage name Silentó, is an American rapper. He is best known for his debut single "Watch Me (Whip/Nae Nae)", which reached number 3 on the Billboard Hot 100.
Career
Silentó's debut single "Watch Me (Whip/Nae Nae)", made with Bolo Da Producer, was released on his YouTube channel on June 25, 2015. Over the course of one week, it gained over 2.5 million views. In April 2015, Silentó was signed to Capitol Records, who released the track as a single with an accompanying music video. It peaked at number three on the US Billboard Hot 100. In June 2015, Silentó performed at the BET Awards, alongside the cast of the show Black-ish.
Discography
Singles
Featured singles
Guest appearances
Awards and nominations
References
Podcasts:
