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The M.A.S. Newsletter
Journal of the Mauritius Astronomical Society
February 2001
The Annual General Meeting will be held at Collège du Saint Esprit, Quatre Bornes on Friday 23rd February at 19:30.
The Sky this Month:
On Friday the 16th of February as from midnight, try to observe the shadow transit of Jupiter's satellite Europa close to the great red spot. A telescope capable of magnifying about 100 times is necessary to view the shadow. On the same day, the Sun enters the constellation of Aquarius. Mercury is in the constellation of Aquarius and by the 11th of March will be at greatest elongation west of the sun and therefore best observed over the eastern horizon in the early morning sky. Venus is now visible as a crescent in small telescopes. You cannot miss it: it is the first object (apart from the Moon!) visible over the western horizon after sunset. By the end of the month its apparent diameter will exceed that of Jupiter. Then on the 30th of March Venus passes at its closest to the Earth but cannot be observed for being too close to the Sun in the sky. On the 27th, the Moon is close to Venus and observable in the western sky after sunset. On the 1st of March, the Moon is again in the constellation of Taurus and in conjunction with Saturn. Try photographing this close encounter. On the 5th of March, Mars is in conjunction with Antares. This event offers an opportunity to compare the planet Mars with its counterpart among the stars Antares "the rival of Ares" (Mars is the Latin name for the Greek god Ares) of the Scorpion. Both are visible in the early morning towards the east. The Delta Leonids meteor shower peaks on Saturday 24th. By the time of maximum visibility, i.e. as from 02:00 in the morning, the Moon will be absent from the sky. The map shows the position of the radiant in the constellation of the Lion high above the eastern horizon.
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Antares:
Antares is the brightest star of the beautiful constellation of the scorpion and therefore also known as a Scorpii. It is a red supergiant very close in colour to the red planet Mars. To the Arabs, it was Calb Al Acrab or the heart of the scorpion. At about 680 times the size of the Sun, Antares is only 15 to 25 times its mass. Its surface temperature is relatively low: 3 100 K. It is an irregular variable star fluctuating between magnitude 0.89 and 1.06. Antares is also a double star with a companion shining at magnitude 6.5 and at an angular distance of 3.0". The star is wrapped in a nebulosity 5 light years in diameter. Its actual luminosity is about 10 000 times that of the Sun and it is found at about 700 light years from us.
Some Astronomical Terms:
Light year: The most common unit of distance in astronomy when measuring distances between stars and between galaxies. The light year (l.y.) is the distance traveled by light through empty space in one year. The light year is equivalent to 9 460 700 000 000 kilometres or 63 240 times the mean Earth-Sun distance. Toliman or a Centauri, the nearest star to the Sun, is at 4.34 l.y. The large Magellanic Cloud (LMC), the closest galaxy visible to the naked eye, is at about 160 000 l.y. The most distant galaxies detected are at about 10 000 000 000 l.y.
Serge Florens, Secretary