The Sun

The sun lies at the heart of the solar system, where it is by far the largest object. It holds 99.8 percent of the solar system's mass and is roughly 109 times the diameter of the Earth — about one million Earths could fit inside the sun.

The visible part of the sun is roughly 10,000 degrees F (5,500 degrees C), while temperatures in the core reach more than 27 million degrees F (15 million degrees C), driven by nuclear reactions. One would need to explode 100 billion tons of dynamite every second to match the energy produced by the Sun.

The sun is one of more than 100 billion stars in the Milky Way. It orbits some 25,000 light years from the galactic core, completing a revolution once every 250 million years or so. The sun is relatively young, part of a generation of stars known as Population I, which are relatively rich in elements heavier than helium. An older generation of stars is called Population II, and an earlier generation of Population III may have existed, although no members of this generation are known yet.

The sun was born roughly 4.6 billion years ago. Many scientists think the sun and the rest of the solar system formed from a giant, rotating cloud of gas and dust known as the solar nebula. As the nebula collapsed because of its gravity, it spun faster and flattened into a disk. Most of the material was pulled toward the center to form the sun.

The sun has enough nuclear fuel to stay much as it is now for another 5 billion years. After that, it will swell to become a red giant. Eventually, it will shed its outer layers, and the remaining core will collapse to become a white dwarf. Slowly, this will fade, to enter its final phase as a dim, cool object sometimes known as a black dwarf.

Sunspots & Solar Cycle

Sunspots are relatively cool, dark features on the sun's surface that are often roughly circular. They emerge where dense bundles of magnetic field lines from the sun's interior break through the surface. The number of sunspots varies as solar magnetic activity does — the change in this number, from a minimum of none to a maximum of roughly 250 sunspots or clusters of sunspots and then back to a minimum, is known as the solar cycle, and averages about 11 years long. At the end of a cycle, the magnetic field rapidly reverses its polarity.

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		Taken on 3/10/2012 Un-modified Canon Rebel XT 350D AstroView 120ST EQ Single Exposure 1/4000 Manually Focused Processed with PhotoShop CS (only to add the text)
		2nd Take... Taken on 3/10/2012 Un-modified Canon Rebel XT 350D AstroView 120ST EQ Single Exposure 1/4000 Manually Focused Processed with PhotoShop CS (only to add the text)
		Taken on 5/27/2012 Un-Modified Canon Rebel XT 350D AstroView 120ST EQ Single Exposure 1/80 ISO 100 Manually Focused Processed with PhotoShop CS (only to add the text)