- Collective term for the Sun and all the objects under its gravitational influence. The last few decades have increased our knowledge of the solar system massively, because of the availability of spacecraft to visit planets and other solar system objects. Since the 1960s, our knowledge of the solar system’s planets and satellites, and its asteroids and comets, and of the Sun itself, has increased many millions of times. We also know that the idea of the solar system as a star, eight planets, and some other miscellaneous objects, is mistaken. Pluto was formerly classified as the ninth planet, but is now seen to be little more than a hefty asteroid and was re-classified a dwarf planet in 2006, while the relationship between the many categories of object in the solar system is becoming steadily clearer. It is now thought that the smaller solar system objects – asteroids, comets and meteoroids – are closely related and are the solar system’s most primitive objects, while the planets and the larger satellites have condensed from material of roughly the same composition as these primordial objects. The formation of planets and large satellites seems to have been a complex process, ranging from the formation of Jupiter – essentially a small-scale act of star formation – down to the glueing together of a small number of planetesimals to form the larger asteroids. As solar system specialist Carl Sagan has said, our era has had the great good fortune to be the one in which the objects of the solar system have been transformed from points of light in the sky to familiar worlds whose nature and origin are well understood.
- A power system incorporating one or more solar panels, along with the necessary structural supports, conductors, storage batteries, inverters, fuses, grounds, and so on.
- A system consisting of a star, along with the planets, asteroids, and other celestial bodies which orbit around it.
- The system consisting of the sun and the planets, asteroids, and other celestial bodies which orbit around it.