The Sun’s dynamic face of sunspots, filaments, granules, and ribbons combines with the chromosphere and multiple prominences to produce a 3-D effect. Taken September 29, 2014, from Carlsbad, California.
Credit: Michael P. Caligiuri
- The Sun, a star similar to others but uniquely close, is significantly larger than Earth (1.3 million Earths could fit inside) and possesses 99.86% of the solar system’s mass.
- The Sun’s physical characteristics include a diameter of approximately 865,400 miles (1,392,700 kilometers), an estimated age of 4.567 billion years, and a surface temperature averaging 9,941° Fahrenheit (5,504° Celsius).
- Despite its perceived yellow color, the Sun is a white star, with its apparent color at the horizon altered by atmospheric refraction.
- Sunlight composition in space consists roughly of 40% light, 50% heat, and 10% ultraviolet radiation; Earth’s atmosphere filters out about 70% of the ultraviolet radiation.
Everyone loves lists, it seems. My three “10 Cool Facts About the Moon” lists proved popular, so I’m following up with three lists about the Sun. Here’s the first one.
1. The Sun is a star. It’s similar to all the stars we see at night. Of course, some of them are hotter, and some are cooler. Some are bigger, some smaller. Some have more mass than the Sun, some less. But the biggest difference between our Sun and all those stars is distance. Even the next-closest star — Alpha Centauri — is more than 250,000 times as distant than the Sun. And our North Star? It’s more than 20 million times as far away!
2. The Sun is so large that 1.3 million Earths could fit inside it. And if you want to compare it to Jupiter, some 1,300 giant planets of that size could fit within our daytime star.
3. The Sun’s diameter is about 865,400 miles (1,392,700 kilometers). That makes it 109 times Earth’s diameter.
4. The Sun’s mass — that is, the amount of stuff that makes it up — is 330,000 times the mass of Earth. In fact, the Sun accounts for 99.86 percent of the mass of our entire solar system. That’s why we call it a solar system, from the Latin word “sol,” meaning Sun.
5. Astronomers estimate that the Sun formed from a huge condensing cloud of dust and gas 4.567 billion years ago.
6. The Sun’s angular size, or how big it appears to us on Earth, ranges from 31.6 arcseconds to 32.7 arcseconds. The average of those extremes equals the size of a quarter 8.85 feet, or 2.7 meters, away.
7. The Sun’s magnitude, or apparent brightness, is −26.74. In common terms, this is some 13 billion times brighter than the next-brightest star, Sirius, in the constellation Canis Major the Great Dog. Let me expand on this a bit. We think of the Full Moon as bright, but its light really is nothing compared to the Sun. The Sun is 1 million times as bright as the Full Moon. In fact, if our sky were filled with Full Moons, they would provide only 20 percent of the Sun’s light.
8. Speaking of sunlight, it’s composed of approximately 40 percent light, 50 percent heat, and 10 percent ultraviolet radiation. Well, in space, anyway. By the time sunlight reaches Earth’s surface, our atmosphere has filtered out some 70 percent of the ultraviolet light.
9. Most people think that the Sun is yellow, but it is, in fact, a white star. It is obviously white from space or when it rides high in our sky. When it approaches the horizon, however, our atmosphere bends the shorter wavelengths (that is, the colors green, blue, and violet) away from our eyes, making a low Sun appear yellow, orange, or red.
10. The Sun’s average surface temperature is 9,941° Fahrenheit (5,504° Celsius). The core’s temperature, on the other hand, is 28.3 million degrees Fahrenheit (15.7 million degrees Celsius).
