Monday, 15 August, 2022

Planets Present Parade In Western Sky


Dr. Rishi Shah

This month's night skies will present a parade of planets that can be observed right from the evening across the western sky along with stunning stars and confounding constellations. Elusive Mercury would be marching through the commanding constellation Sagittarius (archer) and thus savouring it in the daytime would be difficult. Planet Venus could be viewed in south-western sky for a few hours after sundown. It would shine superbly among the stars sketching the north-eastern sector of sprawling Sagittarius.

The Red Planet
The red planet Mars could be traced perhaps towards the end of the month in the eastern sky before dawn. It would be moving during the daytime through the constellation Libra (scales), the north-eastern section of Scorpius (scorpion) and the southern flank of the constellation Ophiuchus (the serpent bearer). The planet Jupiter could be applauded attractively in the southern sky after nightfall. Within a couple of hours, it would be gliding gently through the north-eastern corner of constellations Capricornus (sea goat) and the southern area of constellation Aquarians (water bearer) and descend towards the south-western horizon. The ringed planet Saturn could be spotted serenely for a short time in the south-western sky after sunset.

It would sink slowly through Capricornus towards the horizon. The far-away greenish planet Uranus could be perceived as a lambent light-point in the eastern sky after dusk. It will be browsing through a southern segment of the comely constellation Aries (ram) towards the south-western sky until after midnight. The distant bluish planet Neptune could be affirmed as a shimmering speck of light in the southern sky in the evening twilight. It will be wandering on the eastern flank of Aquarius until late at night towards the southern horizon.
The new moon could be evinced on 04 December, while the full moon would mesmerise moon-enthusiasts on 19 December. The full moon is aptly nicknamed the cold full moon because during this time of year icy winter air would settle in and the nights would become long and dark.

A total solar eclipse would transpire on this day between 11:15 AM and 3:21 PM with the moon completely blocking the Sun. The baffling beautiful solar outer atmosphere dubbed the corona will be resplendently revealed. The track of totality for this eclipse will be limited to Antarctica and the southern Atlantic Ocean.
However, a partial solar eclipse could be watched from South Africa, Namibia, Australia, New Zealand, Chile, Argentina, Falkland Islands and Saint Helena. This eclipse will not be visible to us. Looking at the Sun without any proper eye protection that has not been officially certified would hurt eyesight irreparably.

One should never peer at the sun, even space during solar eclipses with naked eyes or through telescopes or using commonly available commercial shades or gadgets. Solar eclipses could be relished live on the internet and social media or projected images offered by eclipse gazers at schools and public places. The December solstice will fall on 21 December. The South Pole of the earth would be tilted toward the Sun, which would arrive at its southernmost position in the sky and hover directly over the Tropic of Capricorn at 23.44 degrees south latitude. This shortest day and longest night duration would herald the first day of winter (winter solstice) in the Northern Hemisphere and the first day of summer (summer solstice) in the Southern Hemisphere. Christmas will be celebrated on 25 December. The last day of the year on 31 December would bid adieu to Julian's year 2021. The next day on 01 January would happily welcome the New Year 2022 for peace and prosperity.

The prolific Geminid meteor shower could be astounded annually from 07 to 17 December. It will probably peak this year from the night of 13 December until the following morning of 14 December with an expected exhibition of up to 120 multi-coloured meteors per hour. The waxing gibbous moon could wash away most of the fainter meteors but the numerous bright ones could still put up a good scintillating show.
One could enjoy the event from its tenebrous location after midnight until early morning before daybreak in the eastern sky when its radiant point which would nearly coincide with the sparkling Castor (Kasturi) nestled in zodiacal constellation Gemini (twins) from which the meteors would allegedly emanate would be flying high up in the sky. Castor would appear singular to the naked eye, but it is a sextuple star system organised into three binary pairs. It would be simply 52 light-years away. The golden giant star Pollux (Punerbasu) with an extra-solar planet, would be gleaming noticeably near Castor.

It would be purely 34 light-years away. Geminids originate from the remains of debris left behind by an arcane asteroid 3200 Phaethon, which was identified in 1983 by British astronomers Simon Green and John Davis. 3200 Phaethon has been considered a rock comet. Sodium fizzing from the asteroid's surface would cause it to act queerly like a comet. The tiny dregs shed by 3200 Phaethon would plunge into Earth's upper atmosphere at a fascinating speed of thirty-six kilometres per second and vaporise, thereby creating colourful flashes of shooting stars that are manifested as Geminid meteors.

The meteors burn up in the upper atmosphere around 100 kilometres above the earth's surface. In periods of 1.434 years, as this five-kilometre wide asteroid-type object would tumble extremely close by the Sun, more copious rubble would be ejected by thermal fracturing. Comet C/2021A1 (Leonard) could be witnessed wholesomely low across the inky south-western sky after mid-month.

NASA's DART Mission
NASA has launched a space probe aboard a SpaceX Falcon9 rocket from Vandenberg Space Force Base in California that has been designed to crash into an asteroid to divert it off course. The Double Asteroid Redirection Test (DART) has become an ambitious effort to assess how asteroids, which are poised for inflicting harm to lives on earth after their catastrophic collision, could be nudged off course and thus warding off the earth from any destructive danger. The cost of this unique project would be 330 Million USD.

The goal of the mission would be to alter the trajectory of a moonlet asteroid Dimorphos, which is around 160 metres wide. Dimorphous would revolve around the larger 780 meters-wide asteroid Didymos. The impact of DART ramming rigidly into Dimorphos has been scheduled tentatively for 26 September 2022. The binary asteroid configuration of Dimorphos and Didymos would be whooping eleven million kilometres from earth. Since the asteroids' paths would never intersect that of our planet, they had been postulated safe for scrutiny and investigation.

DART is equipped with sophisticated navigational and imaging instruments on board, including the Italian Space Agency's Light Italian CubeSat for Imaging of Asteroids, which will monitor the peculiar pummel of the craft and its aftermath. The DART probe, which would resemble a normal fridge-alike box befitted with limousine-sized solar panels on either side. Weighing fairly 550 kilos, it would slam into Dimorphos at a speed of sheer 6.6 kilometres per second. The target asteroid Dimorphos would scoot around Didymos in eleven hours and fifty-five minutes. It has been anticipated that the hit would save around ten minutes off that time. With an orbital period of merely 770 days around the Sun, Didymos would whizz relatively close to the earth, making it a Near-Earth object (NEO). Experts have identified twenty-seven thousand asteroids near-earth asteroids.
Ten thousand of those asteroids indicate a diameter greater than 140 meters, a size that NASA has deemed big enough to exact major damage to lives and material on earth if they were to smite the earth. They would have the potential to devastate entire cities with their energy of average nuclear bombs. The European Space Agency (ESA) mission Hera was proposed for deployment in 2024 to study in detail the space probe smacking the asteroid. It is estimated that 140 meter-wide asteroids would strike the earth once every twenty thousand years.

Asteroids that are ten kilometres or wider, which are alike those that ostensibly struck earth presumably sixty-six million years ago and triggered the extinction of most life on earth, including those of the dinosaurs could sadly thrash earth again every one to two hundred million years.

(Dr. Shah is an academician at NAST and the Patron of Nepal Astronomical Society, or NASO)