neptune

extremes of cold and wind

Neptunes blue color is mostly because of frozen methane (CH4 ). When Voyager 2 visited Neptune in 1986, there was a large dark-blue spot, which scientists named the Great Dark Spot, south of the equator. When the Hubble Space Telescope took pictures of Neptune in 1994, the Great Dark Spot had disappeared, but another dark spot had appeared north of the equator. Astronomers think that both of these spots represent gaps in the methane clouds on Neptune. The changing appearance of Neptune is caused by its turbulent atmosphere. The winds on Neptune are stronger than on any other planet in the solar system, reaching speeds of 1,100 km/h (700 mi/h), close to the speed of sound. This extreme weather surprised astronomers, since the planet receives little energy from the Sun to power weather systems. Neptunes core is 7000 C (12,632 C) which means that it produces more energy than it receives from the Sun. Neptune is also one of the coldest places in the solar system. Temperatures at the top of the clouds are about -218 C (-360 F). Neptunes composition is that of a gas giant: (1) upper atmosphere, (2) atmo- sphere composed of hydrogen, helium and methane gas, (3) mantle of water, ammonia and methane ice, (4) core of rock and ice.

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neptunes rings and moons

Neptune has faint rings of ice and dust that may change or disappear in fairly short time frames. Neptune has 13 known moons. Triton, shown in Figure 1.3, is the only one of them that has enough mass to be spherical in shape. Triton orbits in the direction opposite to the orbit of Neptune. Scientists think Triton did not form around Neptune, but instead was captured by Neptunes gravity as it passed by. This image of Triton, Neptunes largest moon, was taken by Voyager 2 in 1989.

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neptune

Neptune, shown in Figure 1.1, is the only major planet that cant be seen from Earth without a telescope. Scientists predicted the existence of Neptune before it was discovered because Uranus did not always appear exactly where it should appear. They knew that the gravitational pull of another planet beyond Uranus must be affecting Uranus orbit. Neptune was discovered in 1846, in the position that had been predicted, and it was named Neptune for the Roman god of the sea because of its bluish color. This image of Neptune was taken by Voy- ager 2 in 1989. The Great Dark Spot seen on the left center in the picture has since disappeared, but a similar dark spot has appeared on another part of the planet. In many respects, Neptune is similar to Uranus (Figure 1.2). Neptune has slightly more mass than Uranus, but it is slightly smaller in size. Neptune is much farther from the Sun, at nearly 4.5 billion km (2.8 billion mi). The planets slow orbit means that it takes 165 Earth years to go once around the Sun.

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instructional diagrams

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questions

which is not a characteristic of neptune?

a) it is 2.8 billion miles from the sun

b) one orbit around the sun takes neptune 165 earth years

-->  c) it has a calm atmosphere.

d) it is the 8th planet from the sun

what led scientists to predict the existence of neptune before it was seen?

a) ancient shepherds had a myth of an 4th outer planet.

b) meteorites on earth came from a planet that wasnt any of the known ones.

-->  c) uranus orbit appeared to be affected by the gravitational pull of another planet.

d) none of the above.

neptunes appearance

-->  a) changes because it has a turbulent atmosphere.

b) changes because the gas composition is continually changing.

c) doesnt change because its atmosphere is stable.

d) doesnt change because its gas composition is stable.

what causes neptune to be blue in color?

a) a planet-wide blue ocean

b) frozen water

-->  c) frozen methane

d) no one knows.

dark spots on neptune are storms that come and go.

a) true

-->  b) false

the great dark spot

a) has been around as long as weve been able to observe neptune.

-->  b) disappeared.

c) is a storm that has been going on for centuries.

d) sticks out since it is a reddish color on a blue planet.

where does neptune get its energy?

-->  a) from its extremely hot core.

b) from uranus.

c) from sources outside the solar system.

d) from the sun.

neptunes moon, triton,

a) orbits in the opposite direction from neptune.

b) is the only of neptunes moons to be spherical.

c) was probably captured by neptunes gravity.

-->  d) all of the above

neptune produces more energy than it receives from the sun.

-->  a) true

b) false

neptunes mantle is made of water, ammonia, and methane ice.

-->  a) true

b) false

diagram questions

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