Whenever I walk underneath the Saturn V booster on display at the Kennedy Space Center, the size of it diminishes everything else in the visitor center. But the yellow disk-like object that crosses the sky every day is truly immense. Recall from Greek mythology that Helios drove the chariot containing the sun across the sky every day. A related myth is Icarus, who attempted to escape exile from the island of Crete with his father, Daedalus. Foolish with his sudden freedom, Icarus flew too close to the sun and the wax of his wings melted, plummeting him to death.
Wiki tells that the sun is 74% hydrogen by weight, and 24% helium by weight. The diameter of the earth is 109 earths. It represents 98.6% of the entire solar system's mass. NASA tells that the energy of the sun comes from nuclear fusion reactions that occur deep inside the sun's core. In a fusion reaction, two atomic nuclei join together, creating a new nucleus. Fusion produces energy by converting nuclear matter into energy.
Also, Fewer than 5 percent of the stars in the Milky Way are brighter or more massive than the sun. But some stars are more than 100,000 times as bright as our sun, and some have as much as 100 times the sun's mass. We have a relatively young and special star for a sun!
One of the reasons that we have been unable to duplicate the sun's energy production with hydrogen fusion, is that it takes almost 10x temperatures hotter on earth. The sun's enormous gravitational forces compress the hydrogen gases so tightly that hydrogen fusion occurs without ludicrous temperatures. Also, those sunspots that occur on the sun - do you know they are so large that 20 earths could fit inside one of them?
Sunspots occur when magnetic fields have discontinuities on the earth's surface. The sun has 11-year cycles for sunspots and if plotted over time, the graph appears as a butterfly, with the butterfly's body aligned with the sun's equator and the wings sticking up to roughly 30 degrees in latitude. If you like butterflies, see - Butterflies Escape.
There are other cycles. Sun at its dimmest for nearly a century, say scientists, tells that the sun's energy output varies over a several hundred year cycle. There is a strong correlation between the number of sunspots and the energy radiated by the sun. In the 17th century, we endured the Maunder Minimum, which also happened to be the time of the Little Ice Age. The recent 1985 was probably the grand maximum for this solar cycle, so we should notice fewer sunspots for the next few hundred years. Astronomers warn though, that we will not notice the lower radiated output for another hundred years.
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