What direction is a planet when it is highest in the sky?

Question

An assignment question that I don't really understand, any help would be great. During the night, a planet rises above the horizon, travels across the sky and sets below the
horizon. In which direction would you have to look to observe the planet when it is highest in
the sky? Would an observer in the southern hemisphere look in the same direction?

Answer 1

When the planet is crossing the meridian. The meridian is an imaginary line that goes from the North passing overhead (zenith) to the South. The Sun transits the meridian at approximately noon local standard time.

If you are in the Northern hemisphere you would be looking due South. If you are in the Southern hemisphere you would look due North.

Answer 2

The exact answer to your question depends on the time of year, where the planet is in its orbit in relation to the earth, the location of the observer on the earth, and whether the planet is north or south of the ecliptic at the time. Planets travel no more than 7 degrees north or south of the ecliptic.

As a rough answer, if the observer is more than 7 degrees of latitude north of the Tropic of Cancer (farther north than about 31 degrees north latitude), planets appear in the southern sky when highest regardless of the other factors, just as the moon does. If the observer is more than 7 degrees of latitude south of the Tropic of Capricorn (farther south than about 31 degrees south latitude), planets appear in the northern sky when highest regardless of the other factors, just as the moon does.

For observers between 31 degrees north and 31 degrees south latitude, the answer is much more complicated. If you give me a specific date and planet, I can show you the analysis that determines where it will appear.

Malcolm below has oversimplified and produced a wrong answer. For example, an observer on the equator sees the sun in the northern sky at noon from the March equinox to the September equinox, and in the southern sky at noon from the September equinox to the March equinox. Similarly, the moon and planets can be seen in the northern and southern skies by an observer on the equator depending on other factors. An observer at 1 degree latitude north, technically in the Northern hemisphere, sees pretty much the same as the observer on the equator, proving Malcolm's answer wrong.

Answer 3

It depends, most of the planets travel along the eccleptic, which is roughly the plane of the solar system. So if you are in northern hemisphere you will be looking south, and vice versa in the southern hemisphere provided they are visible when you are trying to observe them. If you live along the the line where the eccleptic is transposed onto the globe you will be looking directly overhead at your zenith.

Answer 4

Not to be too technical here, but I always tell my nephew that it's "out there."