Tuesday, June 14, 2011


The first rare and longest total lunar eclipse of 2011 occurs on Wednesday 15 June 2011. Sky-gazers with clear skies could view this eclipse also from parts of Southeast Asia, eastern Australia, Africa, Europe, the Middle East, South America and Antarctica.

For us, the eclipse will begin at 11:08 PM local time when the moon enters the faint portion (penumbra) of the earth’s shadow. At about an hour later at 00:08 AM after midnight the moons begins to slide into the inky part of the shadow of earth (umbra). Although the penumbra would be slightly discerned, the umbra will be fully visible to eyes when the moon becomes deeply ruddy dark till 03:48 AM in the morning. The total lunar eclipse becomes then obviously evident, when moon is immersed fully into murky umbral shadow of earth from 01:07 AM to 02:47 AM (for 100 minutes). Weather permitting eclipse-chasers could notice the dark and then the light shadow leaving the moon and thus ending the total lunar eclipse at 04:48 AM few hours before the dawn. The moon rises at 06:40 PM on 15 June 2011, while it sets at 05:20 AM in the next morning. The sunrise and sunset on 15 June are at 05:08 AM and 07:01PM respectively. The Sun rises at 05:08 AM and sets at 07:01 PM in the evening on 16 June 2011.

The total length of this lunar eclipse would measure to about five hours and fourty minutes. As the full moon would glide through the middle of umbra, the total lunar eclipse phase would last unusually long for about one hundred minutes just shy of seven minutes for it to become the absolute maximum total lunar eclipse. The moon is approximately 372 thousand kilometers away during the eclipse.

Consequently this total lunar eclipse is relatively long after the ones that have happened before on 16 July 1935 (totality lasting for 101 minutes), 06 July 1982 (totality lasting for 107 minutes) and 16 July 2000 (totality lasting for 107 minutes). The next total lunar eclipse of such lengthy duration will take place on 27 July 2018 with totality lasting for 106 minutes. The moon is moving from zodiacal constellation Scorpius (Brishak) towards Sagittarius (Dhanu) passing predominantly through the constellation Ophiuchus (Bhujak Dhari) during the various phases of the eclipse. The Sun is in zodiacal constellation Taurus (Brish) on 15 June.

The next normal total lunar eclipse can be witnessed on 10 December 2011 by us. The last such total eclipse was visible on 04 March 2007 from Kathmandu.

Lunar eclipses occur only at full moon. Furthermore, the average inclination of lunar orbit to the ecliptic plane is five degrees. However, at every full moon we do not experience eclipse, mainly because the orbit of the moon is inclined in relation to the plane in which earth travels around the Sun and intersect at two points called descending (Ketu) and ascending (Rahu) nodes. The eclipse occurs when the moon appears near or at these nodal points. The orbit of our moon around the earth is completed in approximately 27.3 days. The sunlight with longer wavelengths (red) after passing through earth’s atmosphere that has reached the moon contributes to the faint reddish glow on moon even when moon is totally eclipsed.

Such regular cosmic spectacle caused by celestial movements of the Sun, earth and its moon have had enthralled but also frightened people from different cultures and triggered superstitious beliefs that had even started battles with tragic consequences. However, we would request the eclipse-watchers to enjoy and understand this marvelous celestial event without any kind of fear.

Contact Details:
Nepal Astronomical Society (NASO),P.O.Box: 3459, Ekantakuna, Lalitpur, Nepal,
Email: info.naso@gmail.com,
URL: http://astronomy-nepal.blogspot.com

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