Mergers have left four airline companies controlling more than 80 percent of the U.S. market. And they have been very slow to add new flights. That makes planes more crowded. U.S. airlines are filling more than 85 percent of their seats in some months â close to record levels, according to the government.
Pluto is thought to be made of mostly ice. It probably also has a small rocky core which might contain some metals. The ice on the surface of Pluto is made of frozen nitrogen, methane and carbon monoxide.The ice covering Pluto reflects a lot of sunlight making it appear brighter than it would if it had been covered with a darker rocky material. 1  Javascript must be enabled to use Cool Cosmos.t probably also has a small rocky core which might contain some metals. The ice on the surface of Pluto is made of frozen nitrogen, methane and carbon monoxide. The ice covering Pluto reflects a lot of sunlight making it appear brighter than it would if it had been covered with a darker rocky material.
Earth and the other three inner planets of our solar system (Mercury, Venus and Mars) are made of rock, containing common minerals like feldspars and metals like magnesium and aluminum. So is Pluto. The other planets are not solid. Jupiter, for instance, is made up mostly of trapped helium, hydrogen, and water. In our solar system, the four gas giants are Jupiter, Saturn, Neptune, and Uranus. Planets with their relative sizes to scale. The tiny bluish dot at the lower left is Earth. The tiny red dots to either side are Venus and Mars.