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,
Gustav Holst mer". Holst began composing "The Planets" in 1914; the movements appeared not quite in their final sequence; "Mars" was the first to be written, followed by "Venus" and "Jupiter". "Saturn", "Uranus" and "Neptune" were all composed during 1915, and "Mercury" was completed in 1916. Each planet is represented with a distinct character; Dickinson observes that "no planet borrows colour from another". In "Mars", a persistent, uneven rhythmic cell consisting of five beats, combined with trumpet calls and harmonic dissonance provides battle music which Short asserts is unique in its expression of violence and sheer terror, "... Holst's intention being to