(adsbygoogle = window.adsbygoogle || []).push({}); Question:

Imagine you go out tonight at 9:00pm and see a star rising on the horizon. If you go out tomorrow at the same time, the star will be in a different location. What day would you be able to see the same star rise from the horizon at 10:40pm?

My half-answer:

The difference between a sidereal and a solar day is that the solar day is ~3.9 min longer.

However, I cannot seem to apply this concept to figure out which day the star would rise at 10:40pm.

I have formulated my own equation,

tn = to - 3.9n

Where tn is the final value of time (in this case, 10:40pm), and to is the original value of time (in this case, 9:00pm). n is the number of days (in this case, what we are trying to find).

By substituting values into my equation, I get:

n = (9:00pm - 10:40pm) / 3.9 min

However, I cannot figure out the answer from that. This is a very easy question but I am really stumped. Any help?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Sidereal vs. Solar Day

**Physics Forums | Science Articles, Homework Help, Discussion**