Astronomically.. Tuesday marks the “New Islamic Year” in most of the Islamic world

International Astronomy Center: Most of the Islamic world will sight the crescent moon of Muharram month for the year 1443 H on Sunday, August 8, 2021. However, sighting the crescent on Sunday is impossible from the east of the Islamic world and not possible from the rest of its parts.

Hence there is no possibility to see the crescent on Sunday, neither with the naked eye nor by using a telescope.

Therefore, it is expected that the New Islamic Year will be on Tuesday, August 10, in most countries of the Islamic world.