Albert Einstein. He argued that what we think of as "gravity" could be the influence of mass moving through some as-yet-undetected 4th-dimensional curving of space.
Scientist know this by the color difference on the planets surface.
There are a few planets which have ice. Earth has ice. Mars is believed to contain ice far underneath its surface. Pluto which is no longer classified as a planet has a surface which is completely frozen.
Very little is known about the make up of the surface of the outer planets. The outer planets are generally referred to as gas giants. While most of them are made up of mostly gasses, it is is believed that their cores are made up of liquified heavy metals.
The Jovian planets are gas giants and have no surface.
The inner planets' surface materials differ from the outer planets because the inner planets have rocky surfaces and the outer planets have gas surfaces.
the surface is solid
Jovian Planets do not have a solid surface to stand on.
Of all the planets the surface of Mars is closest to being like Earth.
None of them do. All the outer planets are gas planets while all the inner planets are rocky. You might be thinking of Pluto. It has a solid surface, but it is no longer considered a planet.
earth
The inner planets are all considered rocky planets in that under atmospheric layers, they have a rocky surface. The outer planets are made of gas and liquid, and are called gas giants. They have no solid surface. Also, all the outer planets have rings while the inner planets do not.
The surface temperature of Venus is higher than the surface temperatures of the other inner planets because of its thick atmosphere.