Venus: some ancient cultures recognized its "evening star" and "morning star" appearances as the same object; some thought they were two different phenomena. T

Venus: some ancient cultures recognized its "evening star" and "morning star" appearances as the same object; some thought they were two different phenomena. The ecliptic, physically, is the plane of Earth's orbit around the Sun. It is so named because that is where eclipses happen, when the Moon crosses that plane. (Or other planets; we call that event a transit, but that's the same as a very annular eclipse.) The projection of that plane as viewed on the sky from Earth is a great circle (or slightly offset, because the observer is on Earth's surface not at its center.) If the Earth were transparent, you could see the entire circle. In reality, you see a segment of it from horizon to horizon, as a line. All the planets and the moon seem to stay near the ecliptic in the sky, because their orbits are within a few degrees of coplanar with Earth's.