JOIN USS A Mohan Krishna writes about the annual Perseid meteor showers and how best to watch it. So, don’t miss a date with the shooting stars on August 11 and 12, around which time the showers peak.
Meteors or shooting stars are one of the most amazing events to witness for skygazers. The phenomenon is caused by a tiny particle of dust entering the earth’s atmosphere. As it plunges through the many layers, it collides with air molecules and the friction generated makes it glow, until it eventually burns up.
Most meteors burn up at altitudes of about 100 kilometres above the earth. The larger and slower the meteor, the longer it survives in the atmosphere. Meteors arrive in regular showers or even storms, but storms are much more sporadic than showers.
Viewing
Indians will be able to witness the beautiful Perseid meteor showers which will illuminate the night sky on August 11 and 12. The Perseid meteor shower reaches its peak around the 12th of August every year; its meteors can be seen for about three weeks around this date.
The Perseids are famous for at least a dozen historical records of this shower exist between 36 AD and 1451 AD. This meteor shower is sometimes referred to as the ‘tears of St Lawrence’ as August 10 is the date of the saint’s martyrdom. In 1866, the Italian astronomer Giovanni Nirginio Schiaparelli (1835-1910) demonstrated that the Perseids had the same orbit as the comet Swift-Tuttle also known as 1862 III.
The Perseids can be seen anywhere in the night sky. Wobbly meteors emerge as nippy, petite smudges while the brighter Perseids will hover in the sky for numerous seconds before parting in a succinct trajectory of shimmering smoke.
The Perseids are probably the most watched annual meteor showers, due to its long duration from July 15 to August 25. While the waning gibbous will not be a nuisance this year, there are going to be no moon free periods.
For example, this year, visibility will be somewhat limited by a crescent moon on August 13 which will likely wipe out fainter meteors from view.
The moon will be hovering below and to the left of the Great Square of Pegasus that night and not all that far from the constellation ‘Perseus’, from where the meteors will appear to emanate. If the moon is in your line of sight, block it with your palm or some paper.
Load shedding
The Perseid meteor shower is named after the constellation Perseus, which is located in roughly the same point of the night sky where the Perseid meteor shower appears to originate from.
While this is a useful naming convention, it is inaccurate. The source of the Perseid meteor is actually the debris from comet Swift-Tuttle. Every year, the earth passes through the debris cloud left behind by the comet and is bombarded by ‘falling stars’.
The angle at which the earth hits the cloud makes the shower more visible from the northern hemisphere. This is why August is called meteor month in the northern hemisphere.
While it can viewed by the naked eye, the annual Perseid meteor show may be partially obstructed by the moon, clouds or night mist, so amateur astronomers may want to carry a pair of binoculars or a camera with a telescopic lens.
Even on clear nights, some kind of viewing aid will come in handy for catching sight of the faintest falling stars, aptly named ‘telescopic’ meteors.
If none are available, experts say looking up towards the northeastern sky will suffice. A digital camera atop a tripod will be sufficient to get steady images of the event; even random clicking during ‘prime time’ will catch a few pictures. The camera must be focused on infinity with the shutter open for several minutes to get the best shots.
The meteoric sparkles will obviously last a fortnight; the finest screening is possible during pre-dawn hours from Thursday to subsequent Sunday.
There will, for most observers, be around 15-30 Perseids per hour, with a few sporadic and minor shower meteors added to the mix.
The most marvelous meteor showers were seen in early 1990’s, when innumerable meteors burnt up similar to ‘flare stars’ in an hour. Meteor showers are harmless. Enjoy watching Perseid meteor showers.