neptune's natural satellites

Neptune has 13 known moons. The largest by far is Triton, discovered by William Lassell just 17 days after the discovery of Neptune itself.

The Natural Satellites

(Pronunciation key)>

style="background:#efefef;"\| Diameter (km)	style="background:#efefef;"\| Mass (10¹⁶ kg)	style="background:#efefef;"\| Mean orbital radius (km)	style="background:#efefef;"\| Orbital period^** (d)
Neptune III	Naiad	nye'-ad	align="center"\| 58	align="right"\| ~19	align="right"\| 48,227	align="right"\| 0.294
Neptune IV	Thalassa	tha-las'-a	align="center"\| 80	align="right"\| ~37	align="right"\| 50,075	align="right"\| 0.311
Neptune V	Despina	des-pee'-na	align="center"\| 148	align="right"\| ~210	align="right"\| 52,526	align="right"\| 0.335
Neptune VI	Galatea	gal'-a-tee'-a	align="center"\| 158	align="right"\| ~370	align="right"\| 61,593	align="right"\| 0.429
Neptune VII	Larissa	lah-ris'-a	align="center"\| 193 (208 × 178)	align="right"\| ~490	align="right"\| 73,548	align="right"\| 0.555
Neptune VIII	Proteus	proh'-tee-us	align="center"\| 418 (436 × 416 × 402)	align="right"\| ~5,000	align="right"\| 117,647	align="right"\| 1.122
Neptune I	Triton	trye'-ton	align="center"\| 2700	align="right"\| 2,140,000	align="right"\| 354,800	align="right"\| -5.877
Neptune II	Nereid	neer'-ee-id	align="center"\| 340	align="right"\| ~3,100	align="right"\| 5,513,400	align="right"\| 360.14
\|	S/2002 N 1^*	\|	align="center"\| 60	align="right"\| ~9	align="right"\| 15,728,000	align="right"\| -1879.71
\|	S/2002 N 2^*	\|	align="center"\| 38	align="right"\| ~9	align="right"\| 22,422,000	align="right"\| 2914.07
\|	S/2002 N 3^*	\|	align="center"\| 38	align="right"\| ~9	align="right"\| 23,571,000	align="right"\| 3167.85
\|	S/2003 N 1^*	\|	align="center"\| 28	align="right"\| ~1.5	align="right"\| 46,695,000	align="right"\| -9115.91
\|	S/2002 N 4^*	\|	align="center"\| 60	align="right"\| ~9	align="right"\| 48,387,000	align="right"\| -9373.99

^* Awaiting confirmation and naming.
^** Negative orbital periods indicate a retrograde orbit around Neptune (opposite to the planet's rotation)

Naming notes

Some asteroids share the same names as moons of Neptune: 74 Galatea, 1162 Larissa. Note that Triton did not have an official name until the 20th century. Although the name was suggested in 1880 by Camille Flammarion, it did not come into common use until at least the 1930s. Usually, it was simply known as "the satellite of Neptune" (the second satellite, Nereid, was not discovered until 1949).

Neptune's Natural Satellites

The Natural Satellites

Naming notes

See also