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For example, the Solar System contains all the objects captured by the Sun’s gravity. This includes the 8 planets and their moons, the smaller dwarf planets, the asteroids, comets and interplanetary dust. The Sun accounts for more than 99% of the mass in the Solar System, and generates almost all the energy. The Solar System ends where the influence of the Sun is overcome by the influence of the Milky Way.
Solar can also refer to solar activity on the Sun. The Sun is a magnetic ball of plasma. Because this plasma is constantly moving inside the Sun, it generates powerful magnetic fields which twist and recombine. The amount of solar activity rises and falls over the course of an 11-year cycle. When the magnetic field lines pierce through the surface of the Sun, we see sunspots. These can also be the source of powerful solar flares and coronal mass ejections.
And solar can refer to the capture of the Sun’s power as solar energy. Satellites estimate that there’s a total of 1.366 kilowatts of energy hitting every square meter in space. Using the photoelectric effect, this energy can be converted into electricity to power our homes and devices. Since the Sun will be shining for another few billion years, this is a renewable source of energy that doesn’t harm the environment, apart from building the solar cells that capture the solar energy.
Solar can refer to solar physics, which is the study of our Sun.
We’ve also recorded several episodes of Astronomy Cast about the Solar System. Start here, Episode 49: Mercury.