Download Great Dark Spot

Our Solar System - Neptune
This picture of Neptune was taken by Voyager 2 on August 20, 1989. One of the great
cloud features, dubbed the Great Dark Spot by Voyager scientists, can be seen toward
the center of the image. The bright clouds to the south and east of the Great Dark Spot
constantly change their appearances in periods as short as four hours
.
Our Solar System - Neptune
This is a close-up view of
the Great Dark Spot taken
on the Voyager in August
1989.
NASA
Our Solar System - Neptune
The Giant planets do not have the same kind of layers inside that
the Earth-like planets do. Their evolution was quite different than
that of the Earth-like planets, and they have much more gas and
ice inside. Neptune's interior make-up is primarily methane ice.
Our Solar System - Neptune
Neptune, Roman god
of the sea (eighth
planet from the sun).
Our Solar System - Neptune
Discovered by
Date of discovery
Mass (kg)
Mass (Earth = 1)
Equatorial radius (km)
Equatorial radius (Earth = 1)
Mean distance from the Sun (km)
Mean distance from the Sun (Earth = 1)
Rotational period (hours)
Orbital period (years)
Johann Gotfried Galle
September 23, 1846
1.024e+26
1.7135e+01
24,746
3.8799e+00
4,504,300,000
30.0611
16.11
164.79
Our Solar System - Neptune
Neptune is the outermost planet of the gas giants. It has an
equatorial diameter of 49,500 kilometers (30,760 miles). If
Neptune were hollow, it could contain nearly 60 Earths. Neptune orbits the
Sun every 165 years. It has eight moons, six of which were found by Voyager.
A day on Neptune is 16 hours and 6.7 minutes. Neptune was discovered on
September 23, 1846 by Johann Gottfried Galle, of the Berlin Observatory,
and Louis d'Arrest, an astronomy student, through mathematical predictions
made by Urbain Jean Joseph Le Verrier.
The first two thirds of Neptune is composed of a mixture of molten rock,
water, liquid ammonia and methane. The outer third is a mixture of heated
gases comprised of hydrogen, helium, water and methane. Methane gives
Neptune its blue cloud color.
Neptune is a dynamic planet with several large, dark spots reminiscent of
Jupiter's hurricane-like storms. The largest spot, known as the Great Dark
Spot, is about the size of the earth and is similar to the Great Red Spot on
Jupiter. Voyager revealed a small, irregularly shaped, eastward-moving cloud
scooting around Neptune every 16 hours or so. This scooter as it has been
dubbed could be a plume rising above a deeper cloud deck.
Our Solar System - Neptune
This is a color image of Triton taken by Voyager 2 in August
1989. Triton is Neptune's largest satellite.
Our Solar System - Neptune
This is a computer-gnerated perspective rendering of one of the caldera-like
depressions on Triton, as it would appear if viewed from the northeast.
Our Solar System - Neptune
Voyager 2's parting look
back at the Neptune system
shows a beautiful dualcrescent view of Neptune
and its largest moon Triton.