NASA’s New Horizons probe will fly by Pluto on July 14, becoming the first spacecraft to study Pluto. Here’s what you need to know about the icy world.
1. Is Pluto still a planet? Yes, but it’s now a different kind of planet. Many of us grew up thinking there were nine planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. In 2006, the International Astronomical Union (IAU) touched off a huge debate when it reclassified Pluto as a dwarf planet.
Why the change? Astronomers started finding many more objects in our solar system that are about the same size as Pluto. Rather than call all of these objects planets, the IAU created a new category called dwarf planets. So far, five dwarf planets have been recognized by the IAU: Pluto, Ceres, Eris, Makemake and Haumea. Scientists expect to eventually confirm many, many more dwarf planets. Dwarf planet Ceres currently is being explored by NASA’s Dawn spacecraft.
2. Where is Pluto? It’s about 3.6 billion miles (5.8 billion kilometers) away from the sun in the Kuiper Belt, a disc-like region of space beyond Neptune where thousands of other small, icy objects orbit. The Kuiper Belt is named in honor of Dutch-American astronomer Gerard Kuiper, who theorized about the existence of small bodies beyond Neptune in the 1950s. Objects in this region are called Kuiper Belt Objects (KBOs).
3. How big is Pluto: It’s about the size of the United States, said New Horizons principal investigator Alan Stern.
4. Does Pluto have any moons? It has five: Charon, Nix, Hydra, Kerberos and Styx.
5. What’s the weather like on Pluto? Very cold. It’s about 375 to 400 degrees Fahrenheit below zero.
6. Does Pluto have gravity? Not much. Scientists say a person who weighs 100 pounds on Earth would weigh only 7 pounds on Pluto.
7. Does Pluto have an atmosphere? Scientists say it has a thin atmosphere and that New Horizons has instruments to help learn more about it.
8. What color is Pluto? It’s reddish brown.
9. Who discovered Pluto? Pluto originally was called Planet X by Percival Lowell, the founder of the Lowell Observatory in Flagstaff, Arizona. He was sure a planet existed beyond Neptune but, despite his efforts, he died in 1916 without finding the planet. Amateur astronomer Clyde Tombaugh of Kansas was hired by Lowell Observatory to continue the search and discovered Pluto on February 18, 1930.
10. How did Planet X become Pluto? 11-year-old Venetia Burney of Oxford, England, suggested the name.
11. Is Pluto at the end of our solar system? No, scientists think there are thousands of other worlds beyond Pluto in the Kuiper Belt.
12. Can I see Pluto with my own eyes? Like Clyde Tombaugh, you can see it. But you will need a good telescope.