An astronomical phenomenon is almost going unnoticed in the city. Thursday's full moon, called 'micro-moon', will be the visibly 'smallest' full moon of the year, and the furthest from the earth since 1994. Full moon in apogee (the farthest distance the moon reaches in its orbit around the earth) will be next seen only in 2052. The apogee itself is not very rare. But its coincidence with the full moon is what makes the micro-moon. On Thursday, the apogee and the full moon's rise in the sky will be separated by just two hours. The phenomenon is the exact opposite of the 'supermoon', in which the perigee (moon's closest orbital position around the earth) and the full moon, occur around the same time.
The change, however, can't be easily detected by the naked eye. Pramod G Galagali, deputy director of the Nehru Planetarium, Bang alore, said: "The apogee and perigee are the result of the elliptical orbit of the moon. The difference between the sizes of the new moon during the apogee and perigee will be between 12-13 per cent. At its furthest, the moon is 4,06,700 kilometres (km) away from the earth, and at its closest 3,56,898 km far. The average distance is 3.85 lakh km. It is either 25,000 km more or less than the average during apogee and perigee. Even during the supermoon and micro-moon, it is not easy for the common man to identify it just by sight."
The last full moon in December 2013 was the smallest of that year. But the last one to be called a 'micro-moon' was the one that occurred on November 28, 2012. The apogee and perigee of the moon is also not fixed. Its apogee can range from 4,04,000 to 406,700 km. On Thursday, it will be 406,536 km.
The moon's apogee will be 32 km further away than Thursday on July 28 this year. But the full moon falls on July 12, ahead by 16 days. On Thu rsday, the distance between the apogee and the full moon is just two hours, making the moon look its smallest. The next time the distance will be this close will be on May 13, 2052. The last time the distance was so close was on November 18, 1994.
Galagali said, "There are several conditions that have to connect. For astronomers the apogee is just one moment when the moon is directly opposite to the sun with the earth at the centre. But the apogee occurs during the day time and the moon rise will happen later. The moon would have passed the apogee by the time we see it."
He said it would be easier for the layman to appreciate the moon's orbit and its distance from the earth during the annular eclipse. " When the perigee of the moon coincides with the new moon and an eclipse also occurs, we notice how a smaller moon can eclipse the sun by being closer to the earth," he said.
via Science - Google News http://ift.tt/1kCages
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