<p>It's geomety:</p>
<p>The day has 24 hours.</p>
<p>The circle has 360°.</p>
<p>So the sky &quot;moves&quot; 15° per hour due to the Earth's rotation of 360° in 24 hours once around its axis.</p>
<p>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°.</p>

CC BY-SA 4.0
2022-01-02T18:34:56.493Z
2022-01-02T23:41:23.117Z
2022-01-02T23:41:23.117Z
planetmaker
<blockquote>
<p>If Venus set about 2 hours after the Sun,then it should be about
30degrees to the east of Sun.</p>
</blockquote>
<p>Is there any mathematical formula to get these thing or it's just a pattern?</p>
<p>Source :<a href="https://olympiads.hbcse.tifr.res.in/olympiads/wp-content/uploads/2017/09/INAO2018-Solution-20180130.pdf" rel="nofollow noreferrer">https://olympiads.hbcse.tifr.res.in/olympiads/wp-content/uploads/2017/09/INAO2018-Solution-20180130.pdf</a></p>

<observational-astronomy><the-sun><positional-astronomy>
Rising and setting time of planets in relation to the sun
Particle king
# Rising and setting time of planets in relation to the sun

(Asked by: username_0 on 2022-01-02)

> 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>

**Tags:** observational-astronomy, the-sun, positional-astronomy

---

## 1 answers

### Answer by username_1 on 2022-01-02. Score: 6 | Accepted answer

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°.


---

