If Venus set about 2 hours after the Sun,then it should be about 30degrees to the east of Sun.

Is there any mathematical formula to get these thing or it's just a pattern?

Source :https://olympiads.hbcse.tifr.res.in/olympiads/wp-content/uploads/2017/09/INAO2018-Solution-20180130.pdf


1 Answer 1


It's geomety:

The day has 24 hours.

The circle has 360°.

So the sky "moves" 15° per hour due to the Earth's rotation of 360° in 24 hours once around its axis.

Assuming that an object is approximately fixed at an infinitely distant place within this time span (not true for solar system objects, but as rule of thumb it's ok), an object on the ecliptic plane will be at the horizon 2 hours later than one which preceeds it by 30°.


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