Thursday, February 25, 2010

The Constellations

-By Rishi Shah and Suresh Bhattarai

Throughout human history and across many different cultures, extraordinary names from mythical fables have been associated with distinguished star patterns of various shapes and sizes. Known commonly as constellations, they are seen magnificently all over the night sky. The current 88 constellations as recognised by the apex institution, the International Astronomical Union (IAU), are based on what was historically suggested by veteran Greek-Egyptian mathematician-cum-astronomer Claudius Ptolemy (circa 90-168 AD).

He had propounded the geocentric model of the Solar System and eventually of the universe in 150 AD, which was accepted by the society until the heliocentric model was proposed by Polish astronomer Nicolous Copernicus in 1543. In about 500 AD, Indian mathematician and astronomer Aryabhatta had already divulged an ingenious notion of the heliocentric Solar System independently. Among the constellations, the 12 zodiac manifestations bear special significance both in horoscopic astrology and astronomy.

Zodiacus in Latin figuratively describes the quaint circle of animals. The creation of the zodiacal signs has been motivated by classical figures from the Greek zodiac that represents weird animals, people, tools and mythological hybrids. Furthermore, the constellations through which the Sun traverses within one year are called the zodiacal constellations

Fantasy picture

In colloquial usage, any constellation is a group of celestial bodies, usually observable stars which appear to form a unique fantasy picture in the sky. Astronomers today still utilise old expressions, though the new system focuses primarily on constellations as queer grid-like segments of the celestial sphere. However, in Hindu Vedic astronomy, the 12 constellations of the zodiac are called Raashis. These are exclusively divided into 27 Nakshatras or lunar houses.

In 1922 and 1930, Belgian astronomer Eugene Delporte aided the IAU in partitioning the celestial sphere into 88 constellations, clearly devising their final demarcations. These constellations share the names of their renowned Greco-Roman predecessors, like Auriga (charioteer), Andromeda (chained princess), Orion (hunter), Leo (lion) and Scorpius (scorpion). While such formations were originally linked to mystical events, creatures, devices or persons, the categorisation of the night sky into recognisable displays was important on land and for sea navigation prior to the invention of the compass.

The division of the ecliptic into zodiacal representations allocated with particular stars had presumably originated from Babylonians (who inhabited Mesopotamia that is Iraq today) during the first millennium BC. The ecliptic is the apparent path that the Sun takes in the sky as it seemingly travels on an imaginary celestial sphere in one year. Zodiacal postulation was expounded also in the holy Rigveda roughly in 1700-1100 BC. The ecliptic was then cleaved into 12 equal zones of celestial longitude to create the first known celestial coordinate system, which is ostensibly advantageous over the modern equatorial or ecliptic coordinate system.

The Babylonian calendar assigns each month to a constellation that begins with the Sun’s position at the vernal equinox, which had dwelled then in Aries (ram). Consequently, it was dubbed the Age of Aries. For this reason, the first astrological symbol is Aries even after the vernal equinox has drifted away from Aries and lies presently in Pisces (fishes) due to the precession of the earth.

Popularly identified as precession of the equinoxes (because the equinoxes advance westward along the ecliptic relative to the fixed stars, opposite to the solar motion along the ecliptic), precession of the earth denotes a gravity-induced gradual shift in the orientation of the earth’s axis of rotation, mimicking the wobbling top that traces out a cone, which requires approximately 26,000 years to complete one cycle.

Greek astronomer and mathematician Hipparchus (190-120 BC) is credited for its discovery. As the earth revolves around the Sun, it arrives at two opposite points that are designated vernal and autumnal equinox from where the tilt of its axis (generally twenty three and half degrees to the perpendicular) is neither away from nor towards the Sun, and the Sun hovers vertically above the equator. They occur on March 20 and September 23 this year (2010). The duration of the night and day are almost equal worldwide on these days. If visualised from the earth’s perspective, at equinox, the Sun is at one of these two opposite equinoctial points on the celestial sphere where the celestial equator and ecliptic intersect.

In modern astronomy, a zodiac is a spherical celestial coordinate system. It characterises the ecliptic as its fundamental plane and the position of the Sun at vernal equinox peculiarly as its prime meridian. Since there are merely 365 and one fourth days in one year and 360 degrees in a circle, the Sun is allegedly gliding gracefully along the ecliptic plane at a rate of slightly less than one degree per day.

Traditionally, there were 12 zodiac constellations which were being used by astrologers. These zodiac constellations were separated by exotic boundaries that were adopted from antiquity. Now they have been redefined by astronomers in such a way that the Sun journeys quirkily through 13 constellations annually. The controversial 13th zodiac constellation is the famed Ophiuchus (serpent bearer) that is not embraced as one of the conventional zodiac constellations, even though the Sun spends a substantial amount of time from December 1 to December 19 each year comfortably in Ophiuchus.

The sprawling Ophiuchus alias Aesculapius was the legendry first doctor of medicine that encompasses the Serpens Caput (snake’s head) and Serpens Cauda (snake’s tail). Although the principal northern portion stays above the ecliptic, Ophiuchus’ southern part actually crosses it. The enchanting Scorpius stretches curiously below its feet as well as below the ecliptic.

The stellar arrangement that is not classed as a constellation is referred to as asterism, but nonetheless they are widely recognised by the astronomy community. Some obvious examples of asterisms include the exquisite circlet of Pisces, seven bright stars in the Ursa Major (great bear) known as Saptarsi locally or the Big Dipper or Plough elsewhere, and the large alluring summer triangle that is sketched by the resplendent stars Altair (Sravana), Deneb and Vega (Avijit) and could be viewed in the summer night sky fascinatingly in the Northern Hemisphere. These stars belong to the confounding constellations Aquila (eagle), Cygnus (swan) and Lyra (harp).

Whilst a grouping of stars may be officially labelled a constellation by the IAU, this does not unequivocally say that stars located in that constellation are necessarily gathered together in space. Sometimes they are apparently discerned near to each other, like the awe-inspiring Pleiades (Seven Sisters) that resides bewitchingly in the zodiacal constellation Taurus (bull). They are our bewildering interpretation of two dimensional images made up of stars with varying luminosity and differing distances.

Simple planetarium

To understand the Solar System, zodiac and equinoxes with the movements of the earth, moon, planets and other cosmic entities, the human orrey should prove to be one of the best instruments. It could effectively demonstrate astronomical concepts in a precise manner. The key features of the orbits of the heavenly objects are logically elucidated on the ground in great detail. The human orrey could be further considered as a simple planetarium on a modest ground.

Sky-enthusiasts especially school students and younger generation could play the role of the moving planets and comprehend the existence of our universe and the baffling evolution of lives on our blue planet earth through mind-boggling games and educative activities.

Source: The Rising Nepal, National English Daily,February 24,2010

Thursday, February 18, 2010

विश्‍वव्यापी खगोल महिना- अप्रिल २०१० Global Astronomy month, GAM2010

विश्‍वव्यापी खगोल महिना- अप्रिल २०१०

खगोलको उत्सव जारी राखौं !

विश्‍वव्यापी खगोल महिना- अप्रिल २०१० मा संसार भरिका पेशावार, सिकारु, शिक्षक तथा सोखिन खगोलविदहरुलाई ब्रम्हाण्डको उत्सव मनाउन आहवान गरिन्छ । विश्‍वव्यापी खगोल महिना- एक अन्तराष्ट्रिय आयोजना हो जुन IYA२००९ का उपलब्धिहरुको आधारमा, बिभिन्न गतिबिधिहरु संचालन गरि अनुभव आदान प्रदान गर्न निर्माण गरिएको छ ।

जोशिला व्यक्तिहरुद्वारा अभिप्रेरित तथा उर्जाशिल अन्तरिष्ट्रिय समुदायको क्षमता गत सालको १००HA अन्तर्गत पुष्टि भैसकेको छ । १००HA को ऐतिहासिक सफलताको फल स्वरुप AWB द्वारा विश्‍वभरिका उत्सुक खगोलप्रेमीहरुलाई पूर्ण रुपमा एक महिना (अप्रिल २०१०) भरि खगोलको उत्सव मनाउन आहवान गरिएको हो ।

अप्रिल २०१० मा संसार भरि मनाइने विश्‍वव्यापी खगोल महिना (GAM२०१०) सामुहिक कार्यमा आधारित प्रयास हुनेछ जसको उद्देश्‍य पहिले भन्दा बढी अन्तराष्ट्रिय साथ र सहयोग जुटाउनु तथा सहभागीहरुको बढी भन्दा बढी अन्तरक्रिया गराउनु रहनेछ । GAM२०१० को प्राथमिक भाव विचार, अनुभव र सफलताको आदान प्रदान गरि बिभिन्न समुदायहरुलाई खगोलीय गतिबिधि संचालन गर्न उत्प्रेरित गर्नु रहेकोछ ।

सम्पूर्ण देशका मानिसहरु एकसाथ उमेर, जाती र विश्‍वास भन्दा माथी उठि एकजुट हुने उत्साह- पुर्ण रुपमा ब्रम्हाण्डको आश्‍चार्य प्रति समर्पित- जसले अन्तराष्ट्रिय खगोल वर्ष IYA२००९ लाई दीर्घकालीन बनाउनेछ भन्छन् माइक सिमोन्स, AWB का अध्यक्ष तथा १००HA का उपसभापति । “GAM२०१० त्यो उत्साह र उर्जामा बन्नेछ जुन एक साधारण विचारबाट सुरू भई विश्‍वव्यापी आयोजनामा परिणत हुनेछ । १००HA जस्तै यो पनि खगोल प्रेमी समुदाय बीच एक सामाजिक उत्थान हुनेछ।

उपलब्ध एक महिनामा GAM२०१० का स्थानिय गतिविधि आयोजकहरुलाई २००९को १००HA को तुलनामा ४ वटा मुख्य फाइदा हुनेछ : १) आफुलाई उपयुक्त समय हुने गरि आ-आफ्नो देशमा विस्त्रित योजना तयार पार्न सकिने, २) मौसमले साथ नदिएको खण्डमा बाह्य गतिविधि सोहि महिनामा पुन आयोजना गर्न सकिने, ३) जनमानस तथा सहभागीहरुलाई अझ बढी कार्यक्रम तथा आयोजनासंग साक्षतकार गराउन सकिने र ४) खगोल विज्ञान सम्बन्धि प्रेरणा लिने अवसर- प्रेरणा दिने अवसर- विश्‍वभर खगोलसंग सम्बन्धित व्यक्ति चिन्न सकिने ।

GAM२०१०मा खगोलविद तथा जनमानस दुवैकालागी रोचक कार्यक्रम समावेश गरिएकोछ:

वेधशालाबाट मात्र नभई सार्वजनिक स्थानबाट पनि चन्द्रमा, शनि ग्रह तथा अन्य आकाशिय पिण्ड हेर्न दुर-दर्शक यन्त्र उपलब्ध गराउने, धेरै टाढा अवस्थित पिण्डको पूर्णअँध्यारो आकाशमा अवलोकन गराउने, मेसिअर म्याराथोन, लिरिड उल्का वर्षा अवलोकन तथा खगोल दिवस (अप्रिल २४) को वार्षिकोत्सव मनाउन विभिन्न कार्यक्रमको आयोजना, आदि केहि प्रस्तावित आयोजना हुन भने अन्य कार्यक्रममा खासगरि IYA२००९मा बनाइएका विश्‍वव्यापी कार्यक्रम, ईन्टर्नेटद्वारा नियन्त्रित टेलिस्कोपबाट अवलोकन, विषेश प्रदर्शनिको प्रतक्ष प्रसारण, अन्य प्रदर्शनिहरु, सहभागीहरु माझ विभिन्न प्रतियोगिता, आदि पर्दछन् ।

सबै क्रियाकलापको केन्द्रविन्दु GAM२०१० वेबसाईट हो जसमा सम्पुर्ण कार्यक्रमको जानकारी छ र साथै यो विचार तथा परिणाम आदानप्रदानको थलो पनि हो । अन्तराष्ट्रिय साझेदारीलाई मुख्य आधार मानेर कार्यक्रम आयोजना गरी विश्‍वसमुदायको भावना उजागर गर्नु यसको प्रमुख लक्ष हो ।

GAM२०१० अनलाइन ब्रोडकास्ट च्यानल अन्तर्गत संसारभरिका कार्यक्रम आयोजकहरुले आफ्नो कार्यक्रमको भिडियो राख्‍न पाउने छन्, आफ्नो अनुकुल विषयमा सर्वसाधरण माझ जनचेतना फैलाउन सक्नेछन् तथा आफ्नो कार्यक्रममा संसारको अन्य कुनै भागबाट भएको कार्यक्रम पनि समावेश गर्न सक्ने छन् ।

महत्वपूर्ण जानकारी तथा कार्यक्रमकालागी GAM२०१० ब्लग मा सम्पर्क गर्न सकिनेछ । यसमा GAM ब्लग सँग सम्बन्धित व्यक्तिहरुले कार्यक्रम तथा योजना बारे प्रष्ट पार्नेछन् भने स्थानिय आयोजकहरुले पनि आफ्नो कार्यक्रमको सुचना राख्‍न पाउनेछन् । दर्शकको संख्‍या तथा उत्तेजना बढाउन संचार माध्यमको सहयोग लिइनेछ ।

आउनुहोस र अप्रिल महिनाको यस माहान उत्सवमा सहभागी हुनुहोस किनभने विश्‍वव्यापी खगोल महिनाले संसारभरिका हजारौं मानिस र सैयौं संस्थाहरुलाई आफ्नो उत्सुकता तथा नवाचार आदानप्रदान गर्न र एक व्यक्ति, एक आकाश को भाव उजागर गर्न एकसाथ उभ्याउनेछ ।


थप जानकारीकालागी:

AWB को जानकारी:

AWB (एस्ट्रोनोमर्स विदआउट बोर्डर्स) एक अन्तराष्ट्रिय संस्था हो जुन राष्ट्रिय तथा सांस्क्रितिक सिमाना भन्दा माथी उठी विश्‍वव्यापी खगोलको अपिलहरु बीच सम्बन्ध बनाई समझदारी र सदिक्षा कायम गर्न समर्पित रहेकोछ । AWB ले एक आधारभूत कुराको साझेदारी गर्छ, त्यो हो- आकाशको साझेदारी ।

सम्पर्कको लागि:

माइक सिमोन्स

अध्यक्ष, एस्ट्रोनोमर्स विदआउट बोर्डर्स

सभापति, GAM२०१०, कार्यकारी समुह

‌‌+१ ८१८ ४८६ ७६३३

ओएना सांडू

GAM२०१०, पब्लिक रिलेसन्स कोअर्डिनेटर

+४० ७२४ ०२४ ६२५

नेपाल एस्ट्रोनोमिकल सोसाईटी (नासो)

एच बि कम्प्लेक्स, ललितपुर

Wednesday, February 10, 2010

Observation Programme from the Central department of Physics, Tribhuvan University

An observational programme was held today in the Central department of physics of Tribhuvan University, Nepal by Nepal Astronomical Society. Though the climate was quite disappointing in the previous day, it swaggered the following day. The programme continued for five long hours from 3pm to 8pm. During day time, Sun was shown using solar filter in telescope. There was a long queue of observers for observing the awe-inspiring Sun. They were thrilled to see the Sunspots. Professors and lecturers of Tribhuvan University also participated in observation including the HOD of Physics, Prof. Dr. Lok Narayan Jha.

Followed by the sun observation, a brief introduction to evening celestial bodies and constellation was given including a brief insight to the global astronomy month, GAM2010 to be held in this April globally. As the Sun disappeared in the horizon and night sky slowly began to spread its beauty, the red planet was shown followed by the blue star- Sirius, the Orion nebula and other celestial bodies. Introduction and position of various constellations, stars and other objects were also given to the participants using pointer. Overall, it was a good outreach programme conducted by NASO.

Saturday, February 6, 2010

TWAN in the Land of Himalaya- 2009 Report

In November 2009 one of the last major TWAN activities during the International Year of Astronomy 2009 was collection of programs in Nepal. Based on collaboration with Nepal Astronomical Society, TWAN photographers Babak Tafreshi and Oshin Zakarian traveled to Kathmandu.

Here are the news and photo links

Thursday, February 4, 2010

Night Sky In February 2010!

-By Rishi Shah
The alluring beauty of major planets, enchanting magnificence of arcane galaxies and nebulae along with mysterious entities of the heavens can be relished this month. As it gets dark, the entire sky comes alive with twinkling stars that sketch gorgeous constellations of different sizes and shapes resembling various unique objects. The zodiacal constellations of Pisces (fishes), Aries (ram), Taurus (ram), Gemini (twins), Cancer (crab) and Leo (lion) are unfurling fascinatingly across the sky from western to eastern horizon. Pentagon-alike constellation Auriga (charioteer) is dominating the evening sky with its bright star Capella (Brahma Ridaya) that is roughly fourty three light-years away. Perseus (legendary person) and Andromeda (chained princess) are drifting towards northwestern sky. Ancient constellation Auriga is teeming with fulgent star clusters and exquisite nebulae. It houses remarkable open star clusters M36, M37 and M38, emission nebula IC410 with intriguing Tadpoles, Flaming Star Nebula IC405 as well as the enigmatic pair IC417 and NGC1931 that are popularly recognized as imaginary spider and petite fly. This perplexingly intimidating predator and the cringing prey are barely ten thousand light-years away. They represent young star clusters that have evolved weirdly in interstellar clouds and are embedded bafflingly in glowing hydrogen gas. M38 manifests rich open star cluster, which is spreading out and their stars are slowly escaping over time as they rush around our galactic centre. Though it contains innumerable lurid blue stars, its most lambent star is puzzlingly yellow and it is nine hundred times more luminous than our Sun. M36 and M37 are equally engrossing embodiments of star clusters. All these three clusters are circa four thousand light-years away.

When strange star Epsilon Aurigae fades repeatedly every twenty seven years, it remains dim for two years before becoming lustrous again. It is eclipsed regularly by its dark companion. Starting from August 2009 its obscuration had arrived at its deepest point by December. It is now expected to remain dull and murky throughout 2010, before regaining its normal brightness in 2011. Huge Epsilon Aurigae is supposedly low mass star that is creeping towards its inevitable demise. It is periodically hidden by a single star dwelling in deluding dusty disk, which is estimated to possess a radius of sheer four AU (four times Earth-Sun distance that stretches on average to 150 million kilometers). It is perhaps one half AU thick. (AU is the abbreviation for Astronomical Unit) and is utterly two thousand light-years away. Similarly, eclipsing binary star Zeta Aurigae varies in magnitude with a period of fairly one thousand days. It is modestly eight hundred light-years away. Beguilingly fiery star AE Aurigae is engulfed in enticing emission nebula IC405, which is nicknamed the Flaming Star Nebula.

Unmistakably attractive Orion (hunter) is decorating the eastern sky after sunset. Canis Major (great dog), Canis Minor (small dog), Monoceros (unicorn) and dinky Lepus (hare) are following Orion. Their distinguished stars Betelgeuse (Ardra), Rigel, Procyon (Manda) and Sirius (Lubdhak) are scintillating enthrallingly. If supergiant Betelgeuse would be placed at our Solar System’s center it would extend to planet Jupiter’s orbit. Betelgeuse is about six hundred light-years away. It is reaching the end of its life span. When it would explode (supernova), it would be visible even during the day time. Blue Rigel would pass its supergiant stage soon either collapsing or shedding its outer layers and would transform into white dwarf. It is probably just over seven hundred light-years away. They are practically nine and eleven light-years away. Lengthy watery constellations Hydra (sea serpent), Eridanus (river) and Cetus (whale) are sprawling in southern sky. Tiny constellations Corvus (crow), Crater (cup) and Sextans (sextant) are straddled snugly on Hydra’s back. Bewitchingly giant binary star Mira consists of oscillating variable Mira A and Mira B. It is virtually over two hundred light-years away. Circumpolar constellations Draco (dragon), Cepheus (king), Cassiopeia (queen) and Ursa Major (great bear) are circling Polaris, the Pole Star alias Dhruba Tara, which resides cozily in Ursa Minor (little bear). Our galaxy the Milky Way runs mainly through Lacerta (lizard), Cassiopeia, Auriga and Monoceros from northwest to southeast horizon.

Elusive planet Mercury is hurrying in eastern sky across Sagittarius (archer) and Capricornus (sea goat) before sunup during the beginning of February. Ruddy Mars is blazing in eastern sky in Cancer right after sundown. It is floating above the famed Beehive star cluster (M44).

Minor meteor shower Delta Leonids would peak before dawn in western sky on 24 February with flashes of sporadic shooting stars that would emanate from Leo. Asteroid Vesta-4 would be dashing across the star field of Leo. Comet 81P/Wild is tumbling across Virgo above its resplendent star Spica (Chitra). Comet C/2007Q3 (Sliding Spring) is ploughing towards northeast horizon after crossing constellation Bootes (herdsman). They could be marvelled late at night through good binoculars. New moon falls on 14 February, while full moon (commonly referred to as full snow moon or colourful holi purnima) mystifies us all on 28 February. Venerated Maha Shivaratri is celebrated respectfully on 12 February.
( Note: Er. Rishi Shah, president of Nepal Astronomical Society(NASO) and Academician of Nepal Academy of Science and Technology(NAST) has been writting about astronomy for more than a decade).
Source: The Rising Nepal, National English Daily,Thursday,February 4,2010

Tuesday, February 2, 2010

Hello Red Planet

An observational programme was arranged by Nepal Astronomical Society (NASO) on the premises of H.B. complex, Lalitpur on 29th January, 201o from 6:30pm to 9:00pm. The date was chosen as the opposition of Mars. A part from the beauty of Mars, people also enjoyed the marvelous moon, orion nebula, pleides and other celestial bodies. Overall, "Hello Red Planet" in Nepal was a success.