Terrestrial planet from the original solar nebula. The Solar System has four terrestrial planets: Mercury, Venus, Earth, and Mars. Only one terrestrial planet, Earth, is known to have an active hydrosphere. During the formation of the Solar System, there were probably many more terrestrial planetesimals, but most merged with or were ejected by the four terrestrial planets. Dwarf planets, such as Ceres, Pluto and Eris, and small Solar System bodies are similar to terrestrial planets in the fact that they do have a solid surface, but are, on average, composed of more icy materials (Ceres, Pluto and Eris have densities of 2.17,
The Planets the suite and that the movements on either side are in mirror images. Thus Mars involves motion and Neptune is static; Venus is sublime while Uranus is vulgar, and Mercury is light and "scherzando" while Saturn is heavy and plodding. This hypothesis is lent credence by the fact that the two outer movements, Mars and Neptune, are both written in rather unusual quintuple meter. Holst suffered neuritis in his right arm, which caused him to seek help from several amanuenses in scoring "The Planets". This is clear from the number of different hands apparent in the full score. Neptune was