1999 Eclipse Sequence

This nine image sequence captures the essence of the last total solar eclipse of the Millennium. The central image of totality is a composite from 22 separate negatives which were combined via computer to closely resemble the naked eye appearance of the solar corona. Total Solar Eclipse of 1999 Aug 11 (Lake Hazar, Turkey) .

Unfortunately, not every eclipse of the Sun is a total eclipse. Sometimes, the Moon is too small to cover the entire Sun's disk. To understand why, we need to talk about the Moon's orbit around Earth. That orbit is not perfectly round but is rather oval or elliptical in shape. As the Moon orbits our planet, it's distance varies from 221,000 to 252,000 miles. This 13% variation in the Moon's distance makes the Moon's apparent size in our sky vary by the same amount. When the Moon is on the near side of its orbit, the Moon appears larger than the Sun. If an eclipse occurs at that time, it will be a total eclipse. However, if an eclipse occurs while the Moon is on the far side of its orbit, the Moon appears smaller than the Sun and can't completely cover it. Looking down from space, we would see that the Moon's umbral shadow is not long enough to reach Earth. Instead, the 'antumbral' or negative shadow reaches Earth. The track of the antumbra is called the path of annularity. If you are within this path, you will see an eclipse where a ring or 'annulus' of bright sunlight surrounds the Moon at the maximum phase. Annular eclipses are also dangerous to look directly with the naked eye. You must use the same precautions needed for safely viewing a partial eclipse of the Sun .

Annular Solar Eclipse and the Path of Annularity

Annularity can last as long as a dozen minutes, but is more typically about half that length. Since the annular phase is so bright, the Sun's gorgeous corona remains hidden from view. But annular eclipses are still quite interesting to watch. You can read all about the recent annular eclipse of February 16, 1999 which was visible from western Australia.

Eclipse Frequency and Future Eclipses
During the six Millennium period 2000 BC to AD 4000, Earth will experience 14,263 solar eclipses as follows:

All Eclipses = 14263 = 100.0%
Partial (P) = 5029 = 35.3%
Annular (A) = 4699 = 32.9%
Total (T) = 3797 = 26.6%
Hybrid1(H) = 738 = 5.2%

2Hybrid eclipses are also known as annular/total eclipses. Such an eclipse is both total and annular along different sections of its umbral path.