P. Venugopal

THIRUVANANTHAPURAM: The annular solar eclipse falling on Friday, the longest of the millennium, is a wonderful opportunity for the people of Thiruvananthapuram to understand the celestial phenomenon of eclipses.

Thiruvananthapuram is situated 8 degrees 29 minutes North Latitude and 76 degrees 59 minutes East Longitude. The outline of the moon will start creeping over the bright disk of the sun at 11.05.1 a.m. at this point on Friday.

‘Annularity’ is when the moon, as seen from the earth, does not cover the full disc of the sun when caught in a line. The edges of the sun all the way round will be visible as a bright ring around the dark silhouette of the moon.

A solar eclipse happens when the sun, moon and the earth fall in the same line. The sun’s distance from the earth is about 390 times the moon’s distance from the earth and the sun’s diameter is about 400 times the moon’s diameter. Because these ratios are approximately the same, the sun and the moon as seen from the earth appear to be about the same size.

The moon’s orbit around the earth is an ellipse, as is the earth’s orbit around the sun. So there are periods when the moon is farthest away from the earth and periods when the moon is closest to the earth. The same happens in the case of the sun in relation to the earth.

Total solar eclipse

A total solar eclipse happens when the sun is farther away from the earth because of the earth’s elliptical orbit. The apparent size of the moon as viewed from the earth then is bigger than the sun’s and so the moon’s silhouette, when the three celestial objects fall in a straight line, covers the full disc of the sun as seen from the earth. Annularity occurs when the earth in its orbit is close to the sun and the moon in its orbit is farther away from the earth. On Friday, when eclipse conditions fall into place, the annularity will reach a maximum level of only 91 per cent in Thiruvananthapuram since it is a little to the north of the central line of the path of the moon’s shadow over the earth. The central line of the path of the eclipse is slightly to the south of the southern tip of the Indian peninsula.

The eclipse will start displaying annular condition here by 1.10.50 p.m. and touch the maximum possible annularity level of 91 per cent by 1.14.28 p.m. And the annularity condition of the eclipse will end by 1.18.06 p.m. And the eclipse will end, with the moon’s silhouette completely lifting from the disc of the sun, by 3.05.5 p.m. The annular condition will last for 7 minutes and 15 seconds in Thiruvananthapuram.