The Sun
The Sun's photosphere has a temperature between 4500 and 6000 K (with an effective temperature of 5777 K) and a density of about 2×10−4 kg/m3; other stars may have hotter or cooler photospheres. The Sun's photosphere is composed of convection cells called granules—cells of gas each approximately 1000 kilometers in diameter with hot rising gas in the center and cooler gas falling in the narrow spaces between them. Each granule has a lifespan of only about eight minutes, resulting in a continually shifting "boiling" pattern. Grouping the typical granules are super granules up to 30,000 kilometers in diameter with lifespans of up to 24 hours. These details are too fine to see on other stars.
Read more about this topic: Photosphere
Famous quotes containing the word sun:
“When the spirit brings light into our minds, it dispels darkness. We see it, as we do that of the sun at noon, and need not the twilight of reason to show it us. This light from heaven is strong, clear, and pure carries its own demonstration with it; and we may as naturally take a glow-worm to assist us to discover the sun, as to examine the celestial ray by our dim candle, reason.”
—John Locke (1632–1704)
“Really to see the sun rise or go down every day, so to relate ourselves to a universal fact, would preserve us sane forever.”
—Henry David Thoreau (1817–1862)