Where exactly does 12:01am start on this planet?

Question

Where exactly does 12:01am start on this planet?

Answer 1

GMT is 'world time' everything is offset from there. That's Greenwhich Mean Time and it's in the UK. For example, my zone is Mountain time in the US, so it's GMT-6.

It originally reflected solar time at the the Royal Observatory in Greenwhich, London

It's now Universal Time (and gmt is coordinate with that) off of an atomic clock.

Just to make it fun , the offsets will change depending on dst or not :-)

That's streches my limit--If you want more detailed info...

http://wwp.greenwichmeantime.com/  

Answer 2

There's something called the International Date Line (IDL), roughly on the 180 degree longitude.

This is as far as you can get from GMT - Greenwich Mean Time - the 0 meridian of longitude.  Get out a globe and follow me on this.  To the west, you are now considered East of GMT, and you are later in the day than England.  To the East of the IDL, you are now closer to the West side of GMT.   So if it's Monday on the West side, it's Sunday on the East side.  The IDL has the "earliest" part of our daily timekeeping.

Answer 3

12.01am can be anywhere on the planet if you mean local time.

Otherwise it starts at Greenwich as JohnT says.