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,
Astrology suite "The Planets". Written by the British composer Gustav Holst (1874–1934), and first performed in 1918, the framework of "The Planets" is based upon the astrological symbolism of the planets. Each of the seven movements of the suite is based upon a different planet, though the movements are not in the order of the planets from the Sun. The composer Colin Matthews wrote an eighth movement entitled "Pluto, the Renewer", first performed in 2000. In 1937, another British composer, Constant Lambert, wrote a ballet on astrological themes, called "Horoscope". In 1974, the New Zealand composer Edwin Carr wrote "The Twelve