Earth and Space Sciences: Time Zones

A time zone is a zone on the terrestrial globe that is approximately 15° longitude wide and extends from pole to pole and within which a uniform clock time is used. Time zones are the functional basis of standard of time and were introduced in the late 19th century as railways connected places that had differing local times.

Source Britannica

Australia is divided into three separate time zones:

1. Australian Eastern Standard Time (AEST)
2. Australian Central Standard Time (ACST), and
3. Australian Western Standard Time (AWST)

Source Australia.com

In the Australian summer, New South Wales, Victoria, South Australia, Tasmania and the ACT turn their clocks forward one hour to Daylight Saving Time (DST). Daylight Saving Time begins at 2am (AEST) on the first Sunday in October and ends at 3am (Australian Eastern Daylight Time) on the first Sunday in April.

New South Wales, ACT, Victoria and Tasmania move from AEST to Australian Eastern Daylight Time (AEDT), UTC +11. South Australia and the New South Wales town of Broken Hill move from ACST to Australian Central Daylight Time (ACDT), UTC +10.5.

Daylight saving is not observed in Queensland, the Northern Territory or Western Australia.

Source Australia.com