Why are the signs of the Zodiac on the Ecliptic and not on the Equator?

Question

I know they are on the ecliptic and not the equator, but why is that? The ecliptic appears to move through the year and varies in season. The Equator is much more steady and easier to track. Why did they choose to track the constellations on the Ecliptic instead of the Equator.

Answer 1

In the daylight, you can navigate by the Sun.

At night, you can navigate if you know where the Sun would be, if it wasn't nighttime - if you see what I mean.

The modern and rather weak method is that the Sun is 90 degrees from the Pole Star - if you can see the Pole Star.

The ancient and safer method was that the Sun appears to travel around the Zodiac once a year. If you can recognise one or two Zodiac constellations, you can fill in the rest, trace that huge arc in the sky even if there is quite a lot of cloud, and nail exactly whereabouts on the horizon was sunset and where will be sunrise. Those ancients were smarter than a lot of us think.

Answer 2

The ecliptic is the plane of Earth's orbit, so it's the track of the Sun through the sky. Since all the planets orbit in nearly the same plane, the Moon and all the planets appear within a few degrees of the ecliptic as well.

Ecliptic longitude is only used by astrologers these days. Astronomers do use a grid system that is oriented on the Earth, where the equator is at 0° latitude and the poles at 90° north and south.

Answer 3

All the signs of the zodiac are located on the ecliptic. That's why they are the zodiac signs - the constellations located on the ecliptic were designated the 12 zodiac signs over 2000 years ago (never mind that the earth's axial wobble or precession of the equinoxes has moved the sun one constellation over from the month that constellation was assigned to).

Answer 4

Because the Earth's axis is tilted 23 degrees to the plane of its orbit.