On July 12th the planet passes Psi Capricorni again, this time moving in the opposite direction than previously and 2 closer to it (a consequence of the Southward motion).
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100-170 AD) named the Terebellum ('quadrilateral') in his famous star catalogue, the Almagest. A Martian longitude map by increases by 14.6 every hour, so this allowance should be applied for observations at other times (if the result is greater than 360, subtract 360 to obtain the correct longitude).
The Terebellum are positioned at the rump of the Archer and include the stars 58 Sgr or Sgr (Omega Sagittarii, mag. Those wishing to observe Mars telescopically should consider downloading the free ' Capricorni, mag. The stars are not physically related, since they lie at very different distances from the Earth; the closeness of the two stars is therefore a line-of-sight effect.
Seen through telescopes under dark skies, three dark dust lanes can be seen, from which the nebula gets its name.
At the centre of the nebula is a double star comprising components of 7th and 8th magnitude.
However, the eccentric nature of the Martian orbit is such that true minimum phase does not occur until April 12th, by which time its phase has reduced slightly further to 87%.across the inhabited world.
Telescopically the planet is a disappointing sight, its low altitude and tiny apparent size frustrating most attempts to obtain a steady and clear view of the planet's surface.
Through telescopes, however, each star is seen to be double.