How many gaseous planets are there

The rings do not touch the planet. The Voyager 1 and 2 spacecraft in and sent back detailed pictures of Saturn, its rings, and some of its moons. There are several gaps in the rings that scientists think have originated because 1 the material was cleared out by the gravitational pull within the rings or 2 by the gravitational forces of Saturn and of moons outside the rings. The spokes appear seasonally and their origin is as yet unknown. Titan is even larger than the planet Mercury.

Nitrogen is dominant and methane is the second most abundant gas. Titan may have a layer of liquid water and ammonia under a layer of surface ice. Although conditions are similar enough to those of early Earth for scientists to speculate that extremely primitive life may exist on Titan, the extreme cold and lack of carbon dioxide make it unlikely Figure below.

From Earth, Uranus is so faint that it was unnoticed by ancient observers. William Herschel first discovered the planet in Although Uranus is very large, it is extremely far away, about 2. Light from the Sun takes about 2 hours and 40 minutes to reach Uranus. Uranus orbits the Sun once about every 84 Earth years. Uranus has a mass about 14 times the mass of Earth, but it is much less dense than Earth.

Like Jupiter and Saturn, Uranus is composed mainly of hydrogen and helium, with an outer gas layer that gives way to liquid on the inside. Uranus has a higher percentage of icy materials, such as water, ammonia NH 3 , and methane CH 4 , than Jupiter and Saturn.

When sunlight reflects off Uranus, clouds of methane filter out red light, giving the planet a blue-green color. There are bands of clouds in the atmosphere of Uranus, but they are hard to see in normal light, so the planet looks like a plain blue ball. Most of the planets in the solar system rotate on their axes in the same direction that they move around the Sun. Uranus, though, is tilted on its side so its axis is almost parallel to its orbit.

In other words, it rotates like a top that was turned so that it was spinning parallel to the floor. Scientists think that Uranus was probably knocked over by a collision with another planet-sized object billions of years ago. Uranus has a faint system of rings Figure below. This image from the Hubble Space Telescope shows the faint rings of Uranus. The planet is tilted on its side, so the rings are nearly vertical.

Uranus has 27 known moons and all but a few of them are named for characters from the plays of William Shakespeare. These Voyager 2 photos have been resized to show the relative sizes of the five main moons of Uranus. Scientists predicted the existence of Neptune before it was discovered because Uranus did not always appear exactly where it should appear.

Neptune was discovered in , 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 Voyager 2 in 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 below. Neptune has slightly more mass than Uranus, but it is slightly smaller in size. Neptune is much farther from the Sun at nearly 4. When Voyager 2 visited Neptune in , there was a large dark-blue spot that scientists named the Great Dark Spot, south of the equator. When the Hubble Space Telescope took pictures of Neptune in , 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. This extreme weather surprised astronomers, since the planet receives little energy from the Sun to power weather systems. Neptune is also one of the coldest places in the solar system. Rather than having thin atmospheres around relatively large rocky bodies, the jovian planets have relatively small, dense cores surrounded by massive layers of gas.

Made almost entirely of hydrogen and helium, these planets do not have solid surfaces. Unlike the spherical shapes of terrestrial planets, the jovian planets are all slightly oblong. The jovian planets rotate much faster than any of the terrestrial worlds. Gravity by itself would make a planet spherical, but their rapid rotation flattens out their spherical shapes by flinging material near the equator outward. After size, perhaps the most noticeable difference between the jovian and terrestrial planets involves moons and rings.

The terrestrial planets are nearly isolated worlds, with only Earth 1 moon and Mars 2 moons orbited by any moons at all. In contrast, many moons and rings orbit each of the jovian planets. All four jovian planets have rings, although only Saturn's rings are easily visible from Earth.

Rings are composed of countless small pieces of rock and ice, each orbiting its planet like a tiny moon. The rings look flat because the particles all orbit in essentially the same plane. The rings are located closer to the planets than any of their moderately sized or large moons, but the inner edge of the rings is still well above the planet's cloud tops. Why are the jovian planets so different from the terrestrial planets? We can trace almost all the differences to the formation of the solar system.

The frost line marked an important dividing point in the solar nebula. As Jupiter formed, it grew in size by swallowing up its outer satellites. Its differential rotation an equatorial rotation shorter than the rotation at higher latitudes is evidence of its liquid, gaseous surface. Jupiter is surrounded by a thin ring of dark material and as of April has 63 known moons in orbit around it, the largest of which are Io, Europa, Ganymede and Calliso.

Saturn has the lowest density of any planet in our solar system. It has a rocky core composed of liquid metallic hydrogen and elements consistent with the primordial solar nebula gaseous cloud that formed the solar system. The rings are composed of millions of small particles of rock and ice, each having its own independent orbit around the planet. Uranus is the only gas giant with its equator at a right angle to its orbit. It was also the first planet to be discovered through a telescope.

It has 13 known rings that are dark and composed of dust and particles up to 10 meters in diameter. Uranus has 5 large moons as well as 10 smaller ones that were discovered by the Voyager 2 probe. Its winds can reach up to 2, km per hour, the fastest in the solar system.