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Umbrella sculpture sign, Invercargill, 25 December 2007

This Sundial shows Invercargill Apparent Time which is the time as measured by the Sun's apparent motion. The centre of the shadow cast by the shaft is behind clock time because of the following factors. The Earth's elliptical orbit around the Sun plus its tilted spin axis causes the length of the apparent solar day to fluctuate. Additionally, Invercargill is the western most city in NZ being 895 km west of the 180° (12 hr) meridian from which NZ Standard Time is taken. Therefore, a considerable time correction is necessary for Invercargill. The difference to be added to equate with NZST can be calculated from the Equation of Time graph. Invercargill is also NZ's southern most city so it experiences the longest summer day and shortest winter day.

This sculpture was designed to embrace the people of Invercargill with their time and place in the Universe for the year 2000. The umbrella is one of the oldest inventions and, in this case, symbolises the protector from rain and Sun for the 5103 Invercargill family names below. The spiral handle with its shadow represents the Tangata Whenua and also reminds us that our Solar System is positioned on one of the spiral arms of our galaxy. Invercargill's time and westerly position is demonstrated by the Sundial. Its alignment also recognises J T Thomson who, in 1856, surveyed Invercargill with the main streets due north-south and east-west. Our position on Earth, journey around the Sun, and place in our galaxy is defined by the circumpolar stars shown in the umbrella canopy. This sculpture illustrates the movement of our planet which is spinning at about 1150 km/h (Invercargill), and speeding around the Sun at some 107 000 km/h carrying a unique cargo of life.

Original size: 2592x1944
Timestamp: 2007:12:25 20:10:04
Exposure time: 1/60 s