A star’s life expectancy depends on its mass. Generally, the more massive the star, the faster it burns up its fuel supply, and the shorter its life. The most massive stars can burn out and explode in a supernova after only a few million years of fusion. A star with a mass like the Sun, on the other hand, can continue fusing hydrogen for about 10 billion years. And if the star is very small, with a mass only a tenth that of the Sun, it can keep fusing hydrogen for up to a trillion years, longer than the current age of the universe.
<span>The Leeward side of a mountain range is in fact in a rain shadow. A rain shadow is an area of elevation where little to no rain falls, due to precipitation being forced out of passing clouds on the windward side of the mountain. Precipitation condenses as clouds rise over the mountain, and in general it precipitates as it crests over the mountain, leaving no moisture for the leeward side. An example of this is the American west, just west of the Rockies, where little to no rain falls.</span>
