about time ...

Time is a basic component of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify the motions of objects.

Daylight saving time (DST) is the convention of advancing clocks so that afternoons have more daylight and mornings have less.

In Australia different states have different rules:

• Queensland and Northern Territory does not have DST
• New South Wales, Victoria, Australian Capital Territory (Canberra) and Tasmania observe DST
• Western Australia is in a three year trial period.

In Sydney the Daylight Saving Time starts on the first Sunday in October at 2 AM and ends on the first Sunday in April at 3 AM.

Australian Time Zones
City	State	Standard Time		Daylight Time
Sydney	NSW	AEST	UTC+10	AEDT	UTC+11
Melbourne	VIC	AEST	UTC+10	AEDT	UTC+11
Brisbane	QLD	AEST	UTC+10
Hobart	TAS	AEST	UTC+10	AEDT	UTC+11
Broken Hill	NSW	ACST	UTC+9.5	ACDT	UTC+10.5
Adelaide	SA	ACST	UTC+9.5	ACDT	UTC+10.5
Darwin	NT	ACST	UTC+9.5
Perth	WA	AWST	UTC+8	AWDT	UTC+9
Currently, where applicable, Daylight Saving Time is Off

NOTE: Coordinated Universal Time (UTC) is a high-precision atomic time standard. UTC has uniform seconds defined by International Atomic Time (TAI), with leap seconds announced at irregular intervals to compensate for the Earth's slowing rotation and other discrepancies. This allow UTC to closely track Universal Time (UT), based on the Earth's angular rotation.

The difference between UTC and the old Greenwich Mean Time (GMT) is less than 0.9 second. In most cases we can consider that UTC = GMT

Time zones are expressed as positive or negative offsets from UTC. Local time is UTC plus the time zone offset for that location, plus an offset (typically +1) for daylight saving time, if in effect. UTC replaced GMT on 1 January 1972 as the basis for time reference in different regions.

DST history in NSW...

DST was introduced nationally during World War I from 1 January 1917 to 25 March 1917 and during World War II for three summers, beginning on 1 January 1942.

DST was introduced again in NSW on 31 October 1971 after the Standard Time Act 1971 was voted by the NSW Parliament.

After a referendum held on 1 May 1976, where 1,882,770 electors were in favor; 868,900 were against and 35,507 votes were informal, DST was adopted on a permanent basis.

Currently in NSW the Daylight Saving Time starts on the first Sunday in October and ends at 3 am summer time on the first Sunday in April.

more...

For more information and astronomy enquiries contact the Sydney Observatory:

Watson Road, Observatory Hill
The Rocks NSW
PH: (02) 9241 3767
Web Site: Sydney Observatory