Launched in , New Horizons is the fastest spacecraft to ever leave Earth. It crossed the orbit of Jupiter the next year and has been traveling nearly a million miles a day —but it still took 9. In fact, New Horizons is going so fast—more than 30, miles per hour—that the spacecraft will pass by Pluto in just three minutes.
The entire close encounter lasts for hours, though, with New Horizons making hundreds of observations of Pluto and its five bizarre moons. The first of the highest-resolution images will be released Wednesday afternoon, and the rest of the data will trickle in over the next 16 months. While waiting for the flyby at New Horizons mission headquarters, space writer Nadia Drake answers some of the biggest questions about Tuesday's event.
Simply put, slowing down and orbiting Pluto is nearly impossible if you want to get there in a reasonable amount of time. Launching all that propellent, plus the spacecraft, is pretty much impossible. Read about chasing Pluto's shadow. Even dwarf planet Ceres, which lives much closer to Earth, is too small to be anything but a blurry blob in Hubble pictures. Learn more about Pluto's first close-up. It could be disastrous for the spacecraft to run into a dust particle as it flies through the Pluto system.
Because the spacecraft is going so fast, colliding with something the size of a rice pellet could be catastrophic. Learn what happened when the spacecraft went silent. The images coming back from New Horizons are already by far the best ever taken of the dwarf planet, even though the latest image, on July 12, was taken from about a million miles away.
Also see " Three Possible Plutos ". Check out the weirdest feature I'd like to see on Pluto. Facing away from the sun, that pole is in the dark, except for the soft glow of sunlight reflected off Charon.
Radio signals traveling at the speed of light take 4. So, data received from New Horizons will have been on the road for about as long as it takes to drive between San Francisco and Santa Barbara.
See the first color image of Pluto from New Horizons. New Horizons will take a good, detailed look at Pluto and its large moon Charon in fact, Charon is so large it forms a binary system with Pluto. Check out Pluto's possible polar cap. After New Horizons passes Pluto, it will continue sailing on into the Kuiper Belt, which is a vast, icy debris ring outside the orbit of Neptune. The resonance between the two bodies is highly stable, and is preserved over millions of years. The last time this cycle took place was between to , when Neptune was farther from the Sun than Pluto.
Pluto reached perihelion in this cycle — i. Since , Pluto returned to a position beyond that of Neptune, where it will remain for the following years — i. Much like the other bodies in our Solar System, Pluto also rotates on its axis. It is also worth noting that Pluto and Charon its largest moon are actually more akin to a binary system rather than a planet-moon system.
This means that the two worlds orbit each other, and that Charon is tidally locked around Pluto. In other words, Charon takes 6 days and 9 hours to orbit around Pluto — the same amount of time it takes for a day on Pluto. This also means that Charon is always in the same place in the sky when seen from Pluto. In short, a single day on Pluto lasts the equivalent of about six and a half Earth days.
A year on Pluto, meanwhile, lasts the equivalent of Earth years, or 90, Earth days! And for the entire year, the moon is hanging overhead and looming large in the sky. It has been estimated that for someone standing on the surface of Pluto, the Sun would appear about 1, times dimmer than it appears from Earth. Pluto is a complex and mysterious world with mountains, valleys, plains, craters, and maybe glaciers. Discovered in , Pluto was long considered our solar system's ninth planet.
But after the discovery of similar intriguing worlds deeper in the distant Kuiper Belt, icy Pluto was reclassified as a dwarf planet. Pluto is only about 1, miles wide. At that small size, Pluto is only about half the width of the United States. It's about 3. Pluto is orbited by five known moons, the largest of which is Charon. Charon is about half the size of Pluto itself, making it the largest satellite relative to the planet it orbits in our solar system.
Pluto and Charon are often referred to as a "double planet. Pluto is the only world so far named by an year-old girl. In , Venetia Burney of Oxford, England, suggested to her grandfather that the new discovery be named for the Roman god of the underworld.
He forwarded the name to the Lowell Observatory and it was selected. Pluto's moons are named for other mythological figures associated with the underworld. Charon is named for the river Styx boatman who ferries souls in the underworld as well as honoring Sharon, the wife of discoverer James Christy ; Nix is named for the mother of Charon, who is also the goddess of darkness and night; Hydra is named for the nine-headed serpent that guards the underworld; Kerberos is named after the three-headed dog of Greek mythology and called Fluffy in the Harry Potter novels , and Styx is named for the mythological river that separates the world of the living from the realm of the dead.
Pluto's place in mythology can get a little muddled, so we asked Dr. However, the Greek name "Plouton" from which the Romans derived their name "Pluto" was also occasionally used as an alternative name for Hades. But Pluto is definitely the Roman spelling.
The surface of Pluto is extremely cold, so it seems unlikely that life could exist there. At such cold temperatures, water, which is vital for life as we know it, is essentially rock-like.
Pluto's interior is warmer, however, and some think there could even be an ocean deep inside. If Earth was the size of a nickel, Pluto would be about as big as a popcorn kernel. From an average distance of 3. One astronomical unit abbreviated as AU , is the distance from the Sun to Earth. From this distance, it takes sunlight 5. There is a moment each day near sunset here on Earth when the light is the same brightness as midday on Pluto.
Find out when you can experience "Pluto time" where you live. Pluto's orbit around the Sun is unusual compared to the planets: it's both elliptical and tilted.
Pluto's year-long, oval-shaped orbit can take it as far as One AU is the mean distance between Earth and the Sun: about 93 million miles or million kilometers. But on average, Pluto is 3.
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