These planets are Mercury, Earth, Venus and Mars. The four planetsfurthest from the Sun are known as the Outer Planets, or the Gas Giants. These planets are Jupiter, Saturn, Uranus and Neptune. ... But the Inner Planets don't have many similarities with the Outer Planets.
Inner Planets
1)Small Size:
Earth is the largest of the Inner Planets, with a diameter of 12,756 km (7,926 miles). Mercury is the smallest with a diameter of 4,878 km (3,031 miles).
2)Have solid surfaces and thin/no atmospheres:
In theory, it would be possible to stand on each of the Inner Planets, although you would only survive on Earth.
3)Greater Density:
The size and composition of the planets is caused by the density of the elements that make up the planets. The elements in the Inner Planets are more closely packed together, causing them to be smaller and solid.
The contents of the atmospheres of the Inner Planets varies from planet to planet. Mercury has no atmosphere although Sodium and Helium can be detected above the surface. Venus' atmosphere is mostly Carbon Dioxide with a very small amount of Nitrogen. Earth's atmosphere is mostly Nitrogen with a smaller amount of Oxygen and even smaller amounts of other gases. Mars has a similar composition of carbon dioxide and nitrogen as Venus although has a much thinner atmosphere.
4)Varied Atmospheres:
The contents of the atmospheres of the Inner Planets varies from planet to planet. Mercury has no atmosphere although Sodium and Helium can be detected above the surface. Venus' atmosphere is mostly Carbon Dioxide with a very small amount of Nitrogen. Earth's atmosphere is mostly Nitrogen with a smaller amount of Oxygen and even smaller amounts of other gases. Mars has a similar composition of carbon dioxide and nitrogen as Venus although has a much thinner atmosphere.
Outer Planets
1)Huge:
Jupiter, the largest planet, has a diameter of 142,984 km (88,846 miles). Neptune is the smallest of the Outer Planets with a diameter of 49,532 km (30,779 miles).
2)Balls Of Gas With No Surface:
Most of the Outer Planets are made of gas. It is likely that they have a much smaller solid or liquid centre. It would be impossible to stand on any of the Outer Planets.
3)Smaller Density:
Despite being larger, the elements that make up the Outer Planets are less densely packed together causing them to be quite light for their size.
4)Similar Atmospheres:
The atmospheres of the Outer Planets consist mostly of Hydrogen and Helium, with Methane also being present in the atmospheres of Uranus and Neptune. Other gases are present although in much smaller quantities.
