EDE71610 sun poster:sun poster AW 5/1/09 17:18 Page 1 a guide to THE SUN THE SUN'S VITAL STATISTICS Mean distance from the earth: 92.95 million miles. ... Diameter of core: about 250,000 miles. ... SUNSPOTS & SOLAR FLARES Sunspots are areas where the Sun's light output is restricted to a certain extent by magnetic fields at that point in the photosphere. Sunspots emit a considerable amount of light, but in comparison with the rest of the Sun's surface they appear dark. ...