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,
Imogen Holst by the cellist Steven Isserlis. In 1976, she took legal action over a recording by Japanese electronic composer Isao Tomita of 'The Planets', calling it 'unworthy of my father's creation'. The record, originally issued on the RCA label, was withdrawn from sale, and vinyl copies have subsequently become very rare. In April 1979 Holst was present when the Queen Mother opened the new Britten–Pears School building in Snape. The building included a new library—the Gustav Holst Library—to which Holst had donated a large amount of material, including books which her father had used in his own teaching career. She had