The Sun Is Really White
Although the sun appears yellow when seen from Earth, itís actually white! We see the sunlight after it has been filtered through the Earthís atmosphere. The air scatters that blue component, making the sky appear blue and the sunlight yellow.
How Big Is the Sun?
The Sun is about 1.4 million km across. Inside, it could hold more than one million planets the size of Earth! If you compare the Sun to some other stars in the universe, it isnít all that big. This picture shows the size of the sun compared to one of the largest stars-Betelgeuse.
The Sunís Gases
Clouds of glowing gases often surround sunspots, hovering just above the sunís surface. These are called faculae. Huge loops of gas, called prominences, rise up from the surface at speeds up to 375 miles per second (22,500 mph). Explosions of radiation are called solar flares that are even more violent and spectacular.
Inside the Sun
Inside the sun there is an atom hitting another atom every 0.13 seconds. But if you were an atom, you wouldnít hit another atom for one hundred years. It takes more than a million years for energy from the Sunís core to reach the surface, but from there it only takes 8 minutes for it to get to Earth.
Pairs of Hydrogen atoms are combined to form Helium atoms in a process known as Nuclear Fusion. The Sunís core is 27 times the diameter of Earth. Its temperature is 27 million degrees F.
The matter near the center of the sun is packed so tightly that energy-carrying atoms produced during the nuclear reactions have trouble finding their way through. They bounce from particle to particle in a so-called "random walk pattern". Heat produced in the core spreads through this part in waves.
Energy is carried from the Radiation Zone outward through the Convection Zone. The Convection Zone carries the Sunís energy up to the surface.
Here, smaller convection cells-up to 600 miles across-bubble up to the surface with more energy, giving the surface of the Sun a grainy appearance. The sunshine we see on Earth comes from the photosphere, which is the only part of the sun we can see directly. The corona and flares are only visible during an eclipse. The photosphere is the Sunís surface.
Great Sun Videos
We found a great some with some incredible videos of the Sun. If you'd like to check it out, click on the Sun to the right. A new window will open so you can explore this great site. When you've finished, just close the window and you'll be right back here to learn lots more!
Unless otherwise noted, all images courtesy of NASA. Permission for use at http://www.nasa.gov/gallery/photo/guideline.html.
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