It depends on what time zone you are in.
It is 9:00 I did mental math
If your DS is set to the date/time of your location, it will go by that. Lets say it is June 23, a Tuesday in your location, then it will be Tuesday of June 23.
They're all further ahead. For example... When it is 10:38 p.m. on Monday in California it is: 6:38 a.m. Tuesday in England (8 hours ahead) 8:38 a.m. Tuesday in Greece (10 hours ahead) 3:38 p.m. Tuesday in Japan and.. (17 hours ahead) 7:38 p.m. Tuesday in New Zealand. (21 hours ahead)
The day of the week in Pokemon diamond and pearl, is the same as your handhelds time and date i.e. if it's a Tuesday on your system, it's Tuesday on Pokemon
Tuesday 22-3-2011 in evening time
Japan is nine hours ahead of the UK. So at 4 PM on Tuesday afternoon in the UK it will be 1 AM Wednesday morning in Japan.
In the path between Japan and Jamaica that does not cross the international date line, Japan is farther east.
The date was March eleventh, 2011, at 2:46 JST (Japan Standard Time).
Japan suffered its largest earthquake to date on Friday, March 11, 2011, at 2:46:23 PM (Japan Standard Time) at the epicenter.
1200 American Eastern Standard Time = 1700 UTC 1200 Eastern Daylight Saving Time = 1600 UTC 1200 Eastern Greenland Time = 1300 UTC 1200 Eastern Greenland Summer Time = 1200 UTC 1200 Eastern European Time = 1000 UTC 1200 East Africa Time = 0900 UTC 1200 Eastern European Summer Time = 0900 UTC 1200 Further-Eastern European Time = 0900 UTC 1200 East Timor Time = 0300 UTC 1200 Eastern Indonesian Time = 0300 UTC 1200 Australian Eastern Standard Time = 0200 UTC 1200 Eastern Summer Time = 0100 UTC
Because when flying either to Japan or America, you cross the International Date Line.