Because they are primarily made of light elements, and ices, without much of a rocky core.
The outer (major) planets of our solar system are the 4 gas giants:JupiterSaturnUranusNeptuneFurthermore, 4 out of the 5 dwarf planets are also in the outer solar system, beyond the orbit of neptune:PlutoHaumeaMakemakeEris
Yes, the densities of the solar system planets can generally be grouped into two categories: terrestrial planets (such as Earth, Venus, Mars, and Mercury) with higher densities due to their rocky compositions, and the gas giant planets (such as Jupiter, Saturn, Uranus, and Neptune) with lower densities due to their gaseous compositions.
The solar wind has a stronger effect on inner planets because they are closer to the Sun and therefore experience higher solar wind densities and stronger solar wind speeds. Outer planets are farther away from the Sun and have weaker solar wind interactions due to the decreased solar wind density and speed at their distance from the Sun.
The outer Solar System is the part outside the orbit of Mars. This region of the Solar System is home to four planets and numerous dwarf planets. The planets are Jupiter, Saturn, Uranus and Neptune.
the four outer planets of this solar system are as followed. jupiter, satern, uranus, and neptune.
JupiterSaturnUranusNeptune
The asteroid belt is generally regarded as the boundary between the inner solar system and the outer solar system.
The four outer planets but it depends what you mean by the outer solar system. If the boundary is set at 4 AU, you have Jupiter, Saturn, Uranus and Neptune.
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.
They have in common is that they are the last planets in the solar system
Jupiter is the first of the outer planets. The asteroid belt separates the inner and outer planets.
The outer solar system is thought of as the four outer planets Jupiter, Saturn, Uranus and Neptune plus dwarf planets and other smaller debris further out.