Because the outer planets are composed of mainly gas or ice, whereas the inner planets are composed of rock which has a higher density.
The inner planets (Mercury, Venus, Earth, and Mars) have relatively low orbital inclinations compared to the outer planets (Jupiter, Saturn, Uranus, and Neptune). The inner planets orbit the Sun in a more or less flat plane known as the ecliptic, while the outer planets have more inclined orbits relative to this plane.
Pluto is too small to have sufficient gravity to sustain an atmosphere. Besides, most of the gasses that form planetary atmospheres are liquified by the low surface temperature. With such a sparse atmosphere, Pluto has no real windstorms. Pluto is too small to have sufficient gravity to sustain an atmosphere. Besides, most of the gasses that form planetary atmospheres are liquified by the low surface temperature. With such a sparse atmosphere, Pluto has no real windstorms.
Compared to the four inner planets, these planets:* Are quite large* Are quite massive* Consist mainly of gas* Don't have a surface where you might stand on* Have a low density
There is oxygen on other planets, but its either frozen due to low temperatures, or locked up in a solid molecular form (such as Iron oxide). Smaller planets cant hold it as an atmosphere, since it escapes the low gravity that they have.
Back when Pluto was still listed as a planet it was considered to have the weakest gravity of all the solar system's planets. Now that Pluto has been demoted from planetary status, the planet with the weakest surface gravity is Mercury. While Pluto's gravity is weaker than that of any planet in the solar system, there are still many non-plantery objects with weaker surface gravity.
The sun's gravity has a number of effects on the planets. Primarily, the sun's gravity is what sets the orbits of the 9 planets. With one revolution around the sun equaling a solar year (365.25 days on earth). Planets closer to the sun orbit the sun at higher speeds due the sun's gravity being stronger at short distances (Gravity decreases exponentially as distance increases from an object) The sun's gravity also has major tidal effects on the planets. High and low tides cycles on earth are partially a function of differences in the sun's gravity on different portions of the earth. The sun's gravity pulls slightly more on the side of the earth facing the sun, causing fluids to bulge toward that side resulting in a high tide cycle. On Mercury, where the sun's gravity is much stronger, tidal forces are powerful enough to alter solid rock and effect the planets landscape.
Outer planets are composed mainly of hydrogen and helium gases, along with traces of other elements such as methane, ammonia, and water. These planets have thick atmospheres and relatively low densities compared to the inner, rocky planets of the solar system.
The four outer planets - Jupiter, Saturn, Uranus, Neptune - are gas giants. Compared to the four inner planets:* They are much larger. * They have a much larger mass. * They consist mainly of gas. No surface where you could stand on. * The have a fairly low density.
Dilute gravity refers to a situation where the effects of gravity are weak, such as in regions where the gravitational field is low compared to standard conditions on Earth. This can happen at extreme distances from massive objects like planets or stars, where the gravitational pull is significantly reduced.
The planets follow Kepler's law of planetary motion which says they travel in ellipses. A circle is a special case of an ellipse with eccentricity equal to zero. Some planets have elliptical orbits with very low eccentricity, so their orbits are almost circular.
Hydrogen is the gas most affected by thermal escape in planetary atmospheres. Its low molecular weight makes it more likely to escape a planet's gravitational pull and be lost to space over time. This process is most pronounced for small, low-gravity planets.