I've a question about time calculating.

The sun rises up at 7:30 in 25°E, What time will the sun rise up in 15°E?

What I've tried

$$25° - 15° = 10°$$

By the way

$$10° . 4 = 40 \space \text {minutes}$$

However, it seems wrong.

  • 1
    $\begingroup$ Why does it seem wrong? $\endgroup$
    – bon
    Nov 19, 2017 at 9:10

1 Answer 1


Your maths is not detailed, but you have the correct answer.

The Earth rotates at 15 degrees per hour (360 degrees/24 hours).

The time required to rotate 10 degrees is 10/15 = 0.666 hours, which is 40 minutes.

  • $\begingroup$ Well, "correct" until you consider governments messing around with things like time zones and Daylight Savings Time. at which point this could be better answered on Law.se :-( Oh, and then there's the question of whether 25E and 15E are at the same latitude. If it's winter and 15E is far enough north, the sun will not rise at all. $\endgroup$
    – jamesqf
    Nov 19, 2017 at 19:38
  • $\begingroup$ The sun-rise time will be 6:50 at 15 degrees east longitude provided both the places are at same latitude. $\endgroup$
    – Harish
    Nov 29, 2017 at 6:28

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