Keep your letter short, focused, and interesting. In general, letters should be under 200 words, 150 or less is best; stay focused on one (or, at the most, two) main point(s); and get to the main point in the first two sentences. If possible include interesting facts, relevant personal experience, and any local connections to the issue.
Jupiterâs Moons â 67. Jupiter is swarming with at least 67 moons in orbit around it, the largest number of natural satellites around any of the planets. Jupiterâs 4 largest moons; Ganymede, Callisto, Io and Europa are known as the Galilean Moons, named after their discoverer Galileo Galilei.
| Cool Cosmos. One of Jupiter's moons, Ganymede, is the largest moon in the Solar System. Ganymede has a diameter of 3270 miles (5,268 km) and is larger than the planet Mercury. It has a rocky core with a water/ice mantle and a crust of rock and ice. Ganymede has mountains, valleys, craters and old lava flows.