Solar variation refers to the changes in the amount of energy emitted by the sun that reach the Earth's atmosphere and affecting the planet in different ways. Synonyms for solar variation include solar activity, solar fluctuations, solar cycle, and solar irradiance. Solar activity encompasses all changes in the sun's behavior such as sunspots, solar flares, coronal mass ejections, and solar wind. Solar fluctuations refer to short-term changes in the sun's energy output, while the solar cycle is a periodic 11-year variation in the sun's magnetic activity. Solar irradiance is the total amount of solar radiation received by Earth. These terms are essential in understanding the sun's impact on our planet, including climate change and space weather effects.