Starwatch: Star Showers

A roundup of what to look for in the night sky

Although two partial solar eclipses occur in July- on the 1st and 31st – they are not visible from the Caribbean region. Visitors from northwestern Canada and the extreme northwest of the United States will see a partially eclipsed Sun if they start their journey when the Sun is settling.

July and August are not good months for early evening viewing of the planets since Jupiter and Saturn are in the predawn sky during July, where they make a number of interesting arrangements with the Pleiades, The Seven Sisters, and the “V” of Taurus, The Bull, during the month. They rise just before midnight in the eastern sky towards the end of August and make a dramatic grouping with the last quarter Moon on August 22. Venus is found low in the evening sky during July and August, and tiny Mercury is located near the horizon of the dawn sky, halt-lit at the end of July and an interesting object in a telescope. Mars is too close to the morning horizon during July and August for easy viewing.

The famous Perseid meteor shower is active from July 17 to August 24, and a fast, bright “shooting star” may suddenly streak across the Moonfree evening sky during late July and early August. The peak of the shower occurs on August 12, and although a waxing gibbous Moon will brighten the sky, the shower should still be rewarding, especially just before dawn.

July and August are excellent months for the identification of the southern zodiacal constellation Scorpius, The Scorpion. This constellation is highly interesting to visitors to the Caribbean region since it’s invisible in its entirety, north of latitude 45°N. The British horizon cuts the constellation in half, and it is permanently below the horizon in northern Canada. It is one of the few constellations which resembles its name, and its bright orange-red star, Antares ( “rival of Mars”), vies with the Red Planet in colour and brightness when Mars is in Scorpius.

Scorpius is on the meridian at about 9 p.m. on July 9, followed by the zodiacal constellation Sagittarius, The Archer. The brighter stars of this constellation trace out the shape of a heavenly teapot which seems to be pouring , water on the Scorpion’s tail. If you have binoculars, search the region between Scorpius and Sagittarius for nebulae and star clusters which can be identified with the aid of a star atlas. Look for the circlet of stars Corona Australis, The Southern Crown, below Sagittarius, and the dim stars of the zodiacal constellation Libra, The Scales, to the west of Scorpius.

Crux, The Southern Cross, is visible in the western sky during July and August, unmistakably signposted by the bright “pointers”, Alpha and Beta Centauri, and the crooked square of the constellation Corvus, The Crow, flies above it towards the horizon. Fomalhaut, a bright star marking the eye of Piscis Australis, The Southern Fish, is the brightest star in the southeastern sky at this time of the year.

The northern sky is also full of interest during July and August when Ursa Major, The Big Bear (or the Big Dipper), is seen in the western sky after sunset. The long sprawling shape of Draco, The Dragon, separates The Big Dipper from Ursa Minor, The Little Dipper, with the end of its “handle” marked by Polaris, The Pole Star. The bright star Vega, in the small constellation of Lyre, The Lyre, is unmistakable above the head of Draco. It marks the comer of a right-angled triangle of stars called The Summer Triangle, also called The Navigator’s Triangle, since the three stars are bright enough to be seen at twilight when the horizon is still visible and a “stellar fix” can therefore be made.

Deneb, a bright star in the well-marked constellation Cygnus, The Swan, also called the Northern Cross because of its shape, and the star Altair, in the small constellation, Aquila, The Eagle, mark the other corners of The Summer Triangle, Hercules, The Kneeler, is found to the west of Vega. The circlet of Corona Borealis, The Northern Crown, is found between Hercules and the kite-shaped constellation of Bootes, The Herdsman, which is pinpointed by its bright orange star, Arcturus. If you follow the curve of The Big Dipper, it leads your eye to Arcturus and then on to blue-white Spica, the brightest star in the dim zodiacal constellation, Virgo, The Virgin.

Ophiuchus, The Snake Strangler, straddles the meridian to the east of Virgo; this house-shaped constellation is almost overhead in the late evening sky during July and August.

Note: The star maps for 11 p.m. on July 9 and 9 p.m. on August 9 were drawn for Trinidad but they can be applied to the entire Caribbean region.

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