THE PLANETThe right-hand circle shows the location of the class G star 79 Ceti (in the constellation Cetus). The planet has the lowest (lower limit) mass yet found, 0.22 times that of Jupiter, only 73 percent the mass of Jupiter. The actual mass is likely greater, as the tilt of the orbit is undetermined, but the low lower limit shows the progress that has been made toward finding smaller and smaller planets. The planet orbits 79 Ceti in 76 days (just under Mercury's period around the Sun) in an orbit that averages 0.35 astronomical units from the star (90 percent Mercury's distance from the Sun, 53 million kilometers, or 33 million miles). The orbit is modestly eccentric, the planet going from 0.25 astronomical units at its closest point to 0.45 astronomical units at its farthest. |