Nereid was discovered in 1949 through Earth-based telescopes. Little is known about Nereid, which is slightly smaller than Proteus, having a diameter of 211 mi (340 km). The satellite's surface reflects about 14% of the sunlight that strikes it. Nereid's orbit is the most eccentric in the solar system, ranging from about 841,100 mi (1,353,600 km) to 5,980,200 mi (9,623,700 km).