Annular Solar Eclipse: 21 May 2012 (Eclipse Magnitude : 0.945)

Averagely speaking, any place on Earth should be able to witness an annular or total solar eclipse every few centuries. The previous annular solar eclipse visible in Hong Kong was in 1958. Another one is in 2012. After that we have to wait for more than six centuries, far into the distant future until the next big one come by in 2685. Annular or total solar eclipses occur when the Sun, Moon and Earth are aligned in a straight line. However, as the mutual distances among these three bodies are constantly changing, the occurrence of a total or annular eclipse hinges on whether the whole or only the central portion of the Sun is obscured by the Moon.

Annular Solar Eclipse visible in Hong Kong on 21 May 2012 (Mon)

Solar Eclipse Simulation

Annular Eclipse:

As the Sun is very near to the horizon during the annular phase, those interested in observing should go to a place with unobstructed view of the sky near the horizon in the East-Northeast direction and monitor the cloud condition from time to time.

　

As one needs to watch the Sun in order to observe the eclipse, precaution must been taken. Never look directly at the Sun with your naked eyes because its blaze can cause permanent eye damage or even blindness.

Safe observation of the Sun by projection method

Wanna know more – the Saros

Although the mutual distances among the Sun, Moon and Earth vary every time they get aligned, the variation actually follows a certain pattern. Suppose a solar eclipse occurs on a particular day. After about 18 years have elapsed, the three bodies will return to a nearly identical configuration in space, culminating in the occurrence of a similar eclipse (by “similar” we mean the type and magnitude of eclipse, etc.). Astronomers coined this interval of time the “Saros”*  and the Saros Series contains those consecutive eclipses that are one saros apart in time. Every year, there are two or three times of solar eclipses that are visible somewhere on Earth. Within a Saros, there are about 40 series. For identification, each saros series is accorded with a serial number. The annular solar eclipses visible in Hong Kong in 1958 and 2012 belong to the same Saros Series (numbered 128). The following lists some of the members of Solar Saros 128:

Solar Saros 128

*A Saros is roughly a period of 18 years 11 days and 8 hours

The first solar eclipse of a saros series appears either at the North Pole or the South Pole. Falling under the series, the eclipses drift to the opposite pole gradually. After sweeping the entire Earth, the series ends and the serial number will not be reused. Solar saros 128 starting in A.D. 984 will end in A.D. 2282 and contains 73 solar eclipses including partial, total and annular eclipses, etc.