In today’s world, the science has grown incredibly that we have Hubble Space Telescope launched into space watching the universe in different spectrums. We have satellites for weather predictions; we have Terrestrial Space observatory Telescope's watching for flares in sun and climate in Jupiter. We have even accurately and safely landed man on the moon.
We can even accurately predicate solar and lunar eclipse, the exact points in earth where it would be visible. We have even predicated the next arrival of Halley's Comet and also the distance away from the earth. The next arrival of Halley's Comet is on 28th July 2061, and then on 7th May, 2134 and it will pass within 13.9 million km from earth.
In spite of all these feats, we still haven’t been able to predicate accurately the Eid al-Fitr. In India, all banks and govt office calendars marked 28th July as Eid al-Fitr holiday but it was predicted a day earlier.
The date of Eid al-Fitr for a region is confirmed by the sighting of the new moon.in that particular region. In countries like India, where even the whole nation has same time-zone can't still predicate when the new moon will occur.