# Position of ecliptic in northern hemisphere

1. Apr 13, 2004

### mmwave

I live in the northern hemisphere about 38 degrees latitude. Last week I noticed that the plane of the ecliptic defined by venus mars and jupiter (or was it saturn?) was nearly over head at the zenith. I don't remember seeing this in my past looks at the sky. Is this a once a year thing like the sun crossing the tropic of capricorn and I just never noticed?

2. Apr 14, 2004

### selfAdjoint

Staff Emeritus
The ecliptic is the apparent path of the sun. It is inclined to the celestail equatory by 23.5o. So the maximum angle between your vertical and the sun at your 38o latitude would be the difference: 38 - 23.5 = 4.5o. Less than 5 degrees, not very much.

Now the orbits of the planets are tilted realativ to the earth's orbit, which means that their paths through the sky are not along the exact ecliptic but different circles. So they could very well at some time be 4.5 degrees north of the ecliptic and therefore overhead to you.

All of this can be predicted - google on ephimerides - but it doesn't happen at fixed times of the year; only the earth goes around in a year, the other planets have their own orbital times, all different.

3. Apr 14, 2004

### Integral

Staff Emeritus
At the equinox the sun is crossing the celestial equator, For you the celestial equator runs at 38deg above the horizon. This summer at the solstice the sun (at noon) will be at 38+23.5 or ~61deg (yes I dropped the .5, cus you are not EXACTLY at 38 so this is not an EXACT relationship). According to my globe at this time of the year the sun is about 3deg north of the equator (moving fast though!) So if you were to go outside and measure the length of the noon time shadow (Define noon as when the shortest Shadow is cast, not by your daylight savings time clock) with abit of trig you should find that the sun about ~40deg above the horizon. The sun by definition is on the ecliptic, if you are looking at the Midnight sky the ecliptic is located were the sun will be (or was) in 6 months, so at this time the ecliptic is about 3deg BELOW the equator, for you about 35deg above the horizon. Of the outer planets Saturn's orbit has the greatest angle with the ecliptic about 2.5 deg, so it seems to me at this time of the year the highest any of the outer planets could be in the midnight sky is something less then 40deg (This is for your 38N location) ... Humm.., Perhaps you need to step outside and look again. Are the planets really that high in the sky, looking at the meridian is rather uncomfortable if you are standing up. So if, when you are observing them, your neck is not craned to the breaking point the planets are not near the meridian!

4. Apr 14, 2004

### Janus

Staff Emeritus
I'm going to assume that you made this observation sometime fairly soon after sunset.

The reason being that at this time of the year that's when the ecliptic will be the closest to the zenith in the Northern hemisphere (since the Earth is tilted to the ecliptic, and rotates, the ecliptic will change position with respect to the local zenith over the course of a day.) At your lattitude, it will pass within 15° of the zenith once a day (more precisely, at intervals of exactly one sidereal day) . During at the sumer solstice, it happens at noon. At the winter solstice, it happens at midnight. During the autumnal and vernal equinoxes it happens near sunrise and sunset respectively.

Last edited: Apr 14, 2004
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