Saturday 4 February 2017

The Alpha Centaurid Meteors.

The Alpha Centaurid Meteors are visible in the Southern Hemisphere (but not the Northern Hemisphere) between 28 January and 21 February each year, peaking on 7-8 February, with best viewing at about 5.00 am local time wherever you are, with about 1 meteor per hour appearing to radiate from a point close to the star Alpha Centuari (the radiant point). The Alpha Centaurids can be difficult to spot, not just because of their low density, but because they are among the fastest meteors, crossing the sky and disappearing very quickly; in 2017 this will not be helped by the waxing Moon, which will be half full on 4 February and full on 11 February, making meteor viewing difficult over this time.

The approximate location of the radiant point of the Alpha Centaurid Meteors. Universe Guide.

Metoer showers are thought to be largely composed of material from the tails of comets. Comets are composed largely of ice (mostly water and carbon dioxide), and when they fall into the inner Solar System the outer layers of this boil away, forming a visible tail (which always points away from the Sun, not in the direction the comet is coming from, as our Earth-bound experience would lead us to expect). Particles of rock and dust from within the comet are freed by this melting (strictly sublimation) of the comet into the tail and continue to orbit in the same path as the comet, falling behind over time. The parent body of the Alpha Centaurids is not known, though the path which the meteors follow is; this follows an elliptical path tilted at 105° to the plane of the Solar System, with its perihelion (closest point to the Sun) at about 1 AU (i.e. the same distance from the Sun as the Earth) and an average distance from the Sun of 2.5 AU (about 2.5 times as far from the Sun as the Earth.

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