Planetary configurations?

Question

If the time of observation is midnight, and a planet is at 45 degrees E, what time does it set?

how about if a planet is at western quadrature, when does it rise?

dont answer if u dont know, i need help with it so dont waste yours and my time.

Answer 1

Planets (like the sun) have an apparent rate of 15 degrees per hour.

The time it takes for a planet to set after meridian passage is found with:

Cos(P) = - Tan(LAT)*Tan(DEC)

P being the polar angle at time of setting (if you find it in degrees, then divide by 15 to find number of hours).

If the planet's declination is 0 (or close to it), then the planet sets 6 hours after meridian passage. In your first example, the planet still has 45 degrees to go before meridian passage (I am assuming that your 45 degrees E refers to polar angle, i.e., time before meridian passage).

If by western quadrature you mean 90 degrees behind the sun, then the planet is 6 hours behind the sun. Again, your latitude or the planet's declination may affect the length of time between sun rise and the planet's rise. The planet will rise approximately 6 hours after the sun (could be 4 could be 8...).

Answer 2

The first question: This would actually depend on your latitude because 45 degrees altitude could be along the meridian. So I'm assuming it means 45 degrees along the ecliptic from where it rose. It is 180 degrees from horizon to horizon, so the planet is 1/4 of the way across the sky. It is also assumed that the time from rising to setting is 12 hours, so 1/4 of the way is 3 hours after rising. That means it will be nine more hours before it sets. So 9:00, AM.

The second question: Quadrature means the planet is at a point where the earth forms a 90 degree angle between it and the sun. IOW, it appears to be 90 degrees from the sun in the sky. 90 degrees is six hours. (1/4 of the full circle around the earth, which is 24 hours.) Western quadrature means it is west of the sun. That means it will rise six hours before the sun. Midnight.

I have to disagree with Raymond on the east vs west. A planet at western quadrature would rise about 6 hours *before* the sun.

BTW, both of these questions refer to superior planets. They couldn't be true for Venus or Mervury.

Answer 3

Definately not mercury like that first guy answered. Mercury is too close to the sun to be seen at midnight. It can only be seen near sunrise or sunset.

I am too lazy to do the math for you. I did all that when I was in school longer ago than i am willing to admit here.