The "A to Zee" of Astronomee.

By: Wolf Lange

Sources include: Collins Dictionary of Astronomy 2^nd Edition, Burnhams Celestial Handbook Revised and Enlarged Edition, Patterns in the Sky by Julian DW Staal and the Amateur Astronomers Handbook by JB Sedgwick.

Chondrite – a type of stony Meteorite that contains Chondrules. These are the most abundant class of meteorite in the solar system est. @ 86%. Largely composed of iron and magnesium bearing silicate minerals with a wide range of compositions. A few types are: carbonaceous Chondrites have the highest proportions of volatile elements and are most oxidized whilst enstatite Chondrites contain the most refractory elements (withstanding high temperatures) with "ordinary" Chondrites with intermediate in volatile element element abundance and oxidation state. Trevor Gould of ASSA is known as an expert in meteorites and organising meteorite hunting safaris!

Chryse Planitia – a relatively smooth Martian plain – 1600km across and 2,5km below the average planetary surface. It appears to have suffered water erosion in the past and was chosen as the site of Viking I landing in 1976. (NOTE: solar planetary exploration has introduced a new set of geophysical terminology other examples are mons, valles & rilles .

Cluster – a group of stars whose members are sufficiently close to each other to be physically associated. Broadly clusters are grouped into open clusters e.g. the Pleiades and globular clusters e.g. Omega Centaurus.

Coalsack nebula (Southern Coalsack) – a prominent Dark Nebula about 170 Parsecs distant in the southern constellation of Crux. Can be seen with the nacked eye near and below the Jewel box open cluster. Best seen in winter when the southern cross is well above the horizon in the early evening and away from the city lights.

COBE – Abbreviation for Cosmic Background Explorer. One of the new generation of satellites launched in Nov. 1989, dedicated to the study of cosmic Microwave Background Radiation. Mission life was 4 years. Two cryogenically cooled instruments have observed the sky at infrared wavelength. There are basically three instruments that do whole-sky surveys and are designed to detect fluctuations in brightness of the microwave background. The detailed analysis of fluctuations in temperature will ultimately result in developing cosmological models that determine how the early inhomogeneities collapsed to form the Large-scale structure we see in today’s Universe. Wow!

Cold dark matter – See Dark Matter.

Columba (Dove) – one of a number of the lesser know small constellations making up the 88 named constellations. Situated in the southern hemisphere near Canis Major. It has two bright stars of 2^nd and 3^rd magnitude. Approx. position RA 6h, DEC –35 degrees & an area covered of about 270 sq. degrees.

Constellation – any of the 88 areas into which the whole of the northern and southern hemisphere of the sky is now divided. Also referred to as the Celestial sphere. Every star, galaxy or other celestial body lies within, or sometimes overlaps, the boundaries of one of the constellations. These boundaries were established unambiguously by the IAU (International Astronomical Union) in 1930 along arcs of Right Ascension and Declination for epoch 1875 Jan. 1.

Coordinate system – a system resembling that of latitude and longitude on the earth by which the direction of a celestial body or a point in the sky can be specified. There are 4 basic coordinate systems: Equatorial, Ecliptic, Horizontal and Galactic, each one has a fundamental circle a zero point and coordinates.

Copernicus – Nicolaus Copernicus a Dutch Astronomer proposed and published in 1543 in his book De Revolutionibus a heliocentric solar system using basic ideas of the Ptolemaic system. There was a strong and prolonged reaction – especially by the church – to the Copernican system which effectively displaced (correctly so) the Earth as the Centre of the Universe.

Also a young lunar crater to the south of Mare Imbrium that is 90km in diameter.

Thirdly it’s a NASA Orbiting Astronomical Satellite OAO-3 launched in Aug. 1972 and operating until Dec. 1980, carrying a 0,9m telescope. (So Hubble was NOT the first after all!).

Cosmic dust – small particles or grains of matter found in many regions of space. There size ranges from 10um to less than 0.01um. Thought to be composed mainly of carbon and silicate material with, in some cases, mantles of water, amonia or carbon dioxide ice. Associated with Dark Nebulae.

Crab Nebula (M1; NGC 1952) – a turbulant expanding mass of gas and cosmic dust with luminous twisting filaments of ionized gas lying about 2000 parsecs away in the constellation of Taurus. It is the remnant of a Supernova probably type II, that was almost certainly observed by Chinese and Japanese in 1054.

Crux or Crux Australis (Southern Cross) – a conspicuous constellation in the southern hemisphere only recorded as recent as in the 1500s by early seafarers. The area also contains the brilliant Jewel box cluster and the dark Coalsack nebula.

C-type asteroids – as promised with B-types here it is: the most common class of Asteroid in the outer main belt, having surfaces similar in composition to Carbonaceous Chondrite meteorites. The three sub-classes: B-type asteroids have a higher Albedo than the average C-type and G-types have a stronger UV absorption feature.

Wolf Lange