Pluto Is Only About Half as Wide as the United States

Pluto is small enough that everyday comparisons work. NASA states that Pluto is only about 1,400 miles wide, and that at that size it is only about half the width of the United States. Compared with a more familiar object in the sky, NASA says Pluto is about two-thirds the diameter of Earth’s Moon. It is lighter than its size suggests, too. Because of its lower density, Pluto’s mass is about one-sixth that of the Moon. NASA gives a few other figures. Pluto is about 3.6 billion miles from the Sun, its average temperature is minus 387 degrees Fahrenheit, or minus 232 degrees Celsius, and it has a thin atmosphere composed mostly of nitrogen, methane and carbon monoxide.