Outline of the Solar System
Solar System – gravitationally bound system comprising the Sun and the objects that orbit it, either directly or indirectly. Of those objects that orbit the Sun directly, the largest eight are the planets (including Earth), with the remainder being significantly smaller objects, such as dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly, the moons, two are larger than the smallest planet, Mercury.
2012 phenomenon
In the Solar System, the planets and the Sun lie roughly within the same flat plane, known as the plane of the ecliptic. From our perspective on Earth, the ecliptic is the path taken by the Sun across the sky over the course of the year. The twelve constellations that line the ecliptic are known as the zodiacal constellations and, annually, the Sun passes through all of them in turn. Additionally, over time, the Sun's annual cycle appears to recede very slowly backward by one degree every 72 years, or by one constellation approximately every 2,160 years. This backward movement, called "precession", is due to a slight wobble in the Earth's axis as it spins, and can be compared to the way a spinning top wobbles as it slows down. Over the course of 25,800 years, a period often called a Great Year, the Sun's path completes a full, 360-degree backward rotation through the zodiac. In Western astrological traditions, precession is measured from the March equinox, one of the two annual points at which the Sun is exactly halfway between its lowest and highest points in the sky. At the end of the 20th century and beginning of the 21st, the Sun's March equinox position was in the constellation Pisces moving back into Aquarius. This signaled the end of one astrological age (the Age of Pisces) and the beginning of another (the Age of Aquarius).