Concepts in Astronomy #2. The Ecliptic
The Ecliptic
Understanding what the ecliptic is may be challenging. To put it in simple terms, it is the apparent circle that the Sun describes, as seen from the Earth, on the star constellations over the course of a year. The ecliptic is inclined with respect to the celestial equator (which will be a near future topic in this series) at an angle of 23.44 degrees. All this is keeping Earth as the reference point.
The ecliptic can also be described as a plane, as the picture helps us see, and it is equivalent to the plane formed by the Earth's orbit around the Sun. The inclination angle of 23.44 degrees is the angle that the rotation axis of the Earth has with respect to a perpendicular line to the plane of the ecliptic.
Most of the objects that orbit the Sun are very close to the plane of the ecliptic, assuming that the plane extends itself to cover the solar system. This is why the planets are seen in the sky, roughly in the same band of the sky where the Sun "travels". The constellations which represent the background of the ecliptic are the known constellations of the Zodiac.