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 before Holst's death, and was hailed by astronomers as the ninth planet. Holst, however, expressed no interest in writing a movement for the new planet. He had become disillusioned by the popularity of the suite, believing that it took too much attention away from his other works. In the final broadcast of his Young People's Concerts series in March, 1972, the conductor Leonard Bernstein led the New York Philharmonic through a fairly straight interpretation of the suite, though he discarded the Saturn movement because he thought the theme of old age was irrelevant to a concert for children. The broadcast