Nasa

Sun is 109.2x larger than Earth DATE OF DISCOVERY Unknown Unknown DISCOVERED BY Known by the Ancients Known by the Ancients EQUATORIAL INCLINATION 7.25 with respect to the ecliptic 23.4393 degrees EQUATORIAL RADIUS 695,508 km 6,371.00 km EQUATORIAL CIRCUMFERENCE 4,370,005.6 km 40,030.2 km VOLUME 1,409,272,569,059,860,000 km 3 1,083,206,916,846 km 3 DENSITY 1.409 g/cm 3 5.513 g/cm 3 MASS 1,989,100,000,000,000,000,000,000,000,000 kg 5,972,190,000,000,000,000,000,000 kg SURFACE AREA 6,078,747,774,547 km 2 510,064,472 km 2 SURFACE GRAVITY 274.0 m/s 2 9.80665 m/s 2 ESCAPE VELOCITY 2,223,720 km/h 40,284 km/h

This seemingly simple question doesn't have a simple answer. Everyone knows that Earth, Mars and Jupiter are planets. At least, they are for now. Both Pluto and Ceres were once considered planets until new discoveries triggered scientific debate about how to best describe them—a vigorous debate that continues to this day. The most recent  definition of a planet  was adopted by the International Astronomical Union in 2006. It says a planet must do three things: It must orbit a star (in our cosmic neighborhood, the Sun). It must be big enough to have enough gravity to force it into a spherical shape. It must be big enough that its gravity cleared away any other objects of a similar size near its orbit around the Sun.