अंतरराष्ट्रीय तिथि रेखा

thumb|aantararashtriy tithi rekha aantararashtriy tithi rekha prashant mahasagar ke bich mean 180° deshantar par uttar se dakshin ki or khianchi gee ek kalpanik rekha hai aur isi ke karan tithi mean parivartan hota hai.

• 0° deshantar athava grinavich madhy samay se 180° deshantar tak jane mean 12 samay petiyoan ko par karana p data hai aur poorv ki or gh di ko 12 ghantean age tatha pashchim ki or 12 ghante pichhe karana p data hai.
• is karan se 180° poorv pashchimi deshantar par do alag-alag divas milane se hone vali pareshani ko samapt karane ke lie vaanshiangatan mean huee 1884 ki sabha mean 180° deshantar ko aantararashtriy tithi rekha nirdharit kiya gaya hai.
• gh diyoan ka samay thik rakhane ke lie ek aantararashtriy tithi rekha ke poorv se pashchim ki or jane par ek din ghatate haian tatha pashchim se poorv ki or jane par ek din badhate haian.

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