Australian Time Zones
Published: 2023-02-20 08:00PM
Ken Kousen posted another Tales from the jar side episode covering among other things, time zones in Antarctica.
Let’s replicate his example in Groovy before looking at time zones more broadly in Australia. Why Australia? Well, that’s where I’m from but also there’s a reference in Ken’s article to one of the facts we’ll look at. First, here is the equivalent of Ken’s exploration at the South Pole:
Groovy Shell (4.0.26, JVM: 21.0.6)
Type ':help' or ':h' for help.
-------------------------------------------------------------------------------
groovy:000> import java.time.*
===> java.time.*
groovy:000> southPole = ZoneId.of('Antarctica/South_Pole')
===> Antarctica/South_Pole
groovy:000> dst = southPole.rules.isDaylightSavings(Instant.now())
===> true
groovy:000> "The South Pole ${dst ? 'IS' : 'IS NOT'} currently on DST"
===> The South Pole IS currently on DST
groovy:000>
Without wanting to give away Ken’s punch line, the South Pole, in particular, the Amundsen-Scott station, is currently on daylight saving time. Read his article or attend one of Ken’s talks if you wonder why that might be strange!
Speaking of strange, Ken also mentioned another strange fact related to Australian timezones. Australia has a zone, Eucla, with a 45-minute offset. And that’s not the only interesting fact!
Let’s look at all Australian timezones, including Eucla, and the three Antarctic research stations, Casey, Davis, and Mawson (seen on the right of the above map).
Before we dive into coding, let’s look at the timezones we’re interested in. First a picture showing the main timezones (source: wikipedia):
And now a more complete table:
| Abbreviation | Time zone name | Offset | Where used |
|---|---|---|---|
Australian Central Daylight Time |
UTC +10:30 |
Summer: South Australia, Broken Hill/Yancowinna County in New South Wales |
|
Australian Central Standard Time |
UTC +9:30 |
Winter: South Australia, Broken Hill/Yancowinna County in New South Wales |
|
Australian Central Time |
Often used as an abbreviation for places which switch between ACDT/ACST |
||
Australian Central Western Standard Time |
UTC +8:45 |
Eucla |
|
Australian Eastern Daylight Time |
UTC +11 |
Summer: Australian Capital Territory, New South Wales except Broken Hill/Yancowinna County in New South Wales, Tasmania, Victoria |
|
Australian Eastern Standard Time |
UTC +10 |
Winter: Australian Capital Territory, New South Wales except Broken Hill/Yancowinna County in New South Wales, Tasmania, Victoria |
|
Australian Eastern Time |
Often used as an abbreviation for places in either AEDT or AEST (or switching between them) |
||
Australian Western Daylight Time |
UTC +9 |
Not currently in use |
|
Australian Western Standard Time |
UTC +8 |
Western Australia, Ashmore and Cartier Islands |
|
Cocos Islands Time |
UTC +6:30 |
Cocos (Keeling) Islands |
|
Christmas Island Time |
UTC +7 |
Christmas Island |
|
Lord Howe Daylight Time |
UTC +11 |
Summer: Lord Howe Island |
|
Lord Howe Standard Time |
UTC +10:30 |
Winter: Lord Howe Island |
|
Norfolk Daylight Time |
UTC +12 |
Summer: Norfolk Island |
|
Norfolk Time |
UTC +11 |
Winter: Norfolk Island |
|
French Southern and Antarctic Time |
UTC +5 |
Heard and McDonald Islands |
|