Earth's Moon is a small ball of gray rock revolving 239,000 miles around Earth. It is just one of many in the solar system. The Moon has no air and no water. It is about one-fourth as large as Earth.
Moonshine is the Sun's reflection off the Moon. It arrives on Earth in little more than a second after leaving the Moon.
“The Man in the Moon” is the name for the dark shadow of craters and lowlands that appear to those of us in the Northern Hemisphere as a face. In the Southern Hemisphere, however, the Moon appears upside down and appears to people to look like an old woman with a bundle of twigs.
Full Moon and No Moon describe two phases of the Moon as it orbits Earth. When the Moon is between the Sun and the Earth, its sunlit side is turned away from the Earth and we say there is no Moon. When the Earth is between the Sun and Moon, we can see the entire sunlit side of the Moon and call it a full Moon.
The Far Side of the Moon is always facing away from Earth because of the force of gravity. So when we look at the Moon, we always see the same side.
Moonwalkers: Twelve American astronauts have walked on the Moon. They explored highlands and craters, took photographs, and gathered soil and rocks for study. On July 20, 1969, when the American astronaut Neil Armstrong became the first person to set foot on the Moon, he said, “That's one small step for a man, one giant leap for mankind.”
The moons of Jupiter: Jupiter has 63 moons. 45 of these moons were discovered between 2000 and 2003. Astronomers believe that the moon count of Jupiter could go as high as 100. The newer moons were named after members of the god Jupiter's (Zeus to the Greeks) entourage, among them: Themisto, Iocaste, Harpalyke, Praxidike, Taygete, Chaldene, Kalyke, Callirrhoe, Megaclite, Isonoe, and Erinome.
The moons of Saturn: Saturn has 46 moons. 12 of them were discovered in late 2004 and announced in May 2005. The larger moons with regular circular orbits were named after figures in Greek mythology (Pan, Atlas, Pandora, Calypso, etc.). The smaller moons with irregular orbits were named after Norse (Ymir, Thrym, Skathi, Suttungr, Mundilfari), Celtic (Tarvos, Albiorix), and Inuit (Paaliaq, Siarnaq, Kiviuq, Ijiraq) legends.
The moons of Uranus: Uranus has 27 moons. Astronomers detected five of them between 1787 and 1948. The space probe Voyager discovered 10 more in 1985 and 1986. The names of these moons are the names of characters from plays by Shakespeare. They are: Oberon, Titania, Umbriel, Ariel, Miranda, Puck, Portia, Juliet, Cressida, Rosalind, Belinda, Desdemona, Cordelia, Ophelia, and Bianca. Miranda, with its deep scars and jumbled surface, is one of the strangest objects in the solar system. It seems to have been shattered by a collision, then pulled back together by gravity! In 1997, two more moons were discovered, Caliban and Sycorax—also characters from Shakespeare. 1999 brought Stephano, Prospero, and Setebos. A satellite discovered in 2001 was dubbed Trinculo.
The moons of Neptune: Neptune has 13 moons, with Triton the largest. It is covered with a frosty crust, where active volcanoes shoot crystals of nitrogen that look like geysers. The surface temperature of Triton is –390°F, making it the coldest object in the solar system. Five new Neptunian moons were discovered in 2002 and 2003.
The moon of Pluto: Pluto has 1 moon, Charon. It was discovered in 1978. Because Charon is a relatively large moon—one-fourth the size of Pluto—it is called a “double planet.”