Solar Eclipse 22nd July 2009

The longest total solar eclipse of the 21st Century occurred on the 22nd July 2009. Its unusual length of 6min 39secs at maximum was due to a number of factors:

• the eclipse occured when the Moon was near perihelion (largest apparent diameter as seen from Earth) and the Earth was near aphelion (smallest apparent solar diameter),
• maximum eclipse occurred near the equator so the observer was physically closer to the Moon by an Earth radius, and
• the Earth's rotation maximises the motion of the observer within the Moon's shadow thereby partially offsetting the speed of the Moon's shadow across the Earth's surface.

The first two factors contributed to the Moon's apparent diameter being around 8% larger than the Sun's.

The path of totality started at sunrise in India, passed through Tibet and Bhutan before heading across very populous regions of China before heading off over the Pacific south of Japan to leave finally the Earth at sunset in the central Pacific.

Local weather conditions were always going to be a critical factor. As it turned out conditions were not favourable where I was together with a thousand or more like minded souls, at the Qiantang River Tidal Bore observation area near Hangzhou, China. Partial phases leading to totality were generally obscured by cloud and there were intermittent rain showers and lightning activity to the north.

The air temperature cooled noticably in the lead up to totality. We were then treated to an awesome fade in light before being plunged into deep darkness as totality ensued above the thick blanket of cloud. We cheered and clapped our hands to greet the Moon's umbra, whilst across the river bank the Chinese celebrated in typical fashion with a firework display. 5min 40secs later the light rose again and, unexpectedly, there was a hint of exit diamond ring visible through a very brief break in the clouds. It was all over, but extremely memorable.

The partial phases to 4th contact were more easily observed through high cloud.

An hour and a half after 4th contact we were treated to the world famous tidal bore, a meter high wave that raced up stream to return water on the incoming high tide.  

Below are some of my images:

	Five minutes after first contact, Sun behind thick clouds. Some of the one thousand or more eclipse observers. This image and those following were taken using the same camera settings in MANUAL - an attempt to show the relative light levels during the eclipse.
	10 mins to second contact and totality.
	5 mins to totality.
	2 mins to totality - getting very dark.
	Mid totality - as dark as night. Thick cloud prevented any direct illumination from the eclipsed Sun.
	2 mins after third contact and end of totality.
	5 mins after totality, light levels are rising fast.
	20 mins after third contact - light levels nearly normal.
	Fourth contact - eclipse is over. Sun shining through thin clouds and normal light levels return.
	15 mins before totality, the Sun breaks through a gap in the clouds.
	2 minutes after totality, the thin crescent Sun appears, to remind us about what might have been.
	The tidal bore racing up stream.

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