How is the ecliptic oriented relative to the equator?
In this illustration we pretend the solar system is horizontal (the usual way we think of it). Since the Earth axis is tilted about 23 degrees away from the Solar system plane, the Earth’s Equator will tilt up by that same 23 degrees as illustrated. There are two places where the curves cross – each are the “Equinoxes” – in the Spring is the Vernal Equinox – in the Fall is the Autumnal Equinox. (In fact, if we want to talk about where planets are relative to each other, we need a way to measure the angles from the Sun. The “reference direction” chosen is the line that connects the Earth and the Sun at the moment of the Spring Equinox {where the two curves to the left intesect}. Continue that line through the Sun and out the other side, and it becomes the line in space that we start the angles from.
