Images of the dwarf planet Pluto taken by NASA's Hubble Space Telescope. CREDIT: NASA, ESA, and M. Buie (Southwest Research Institute)
Pluto is so far away from Earth that everything we know about it can be written down on a couple of 3 x 5 inch index cards. Pluto will come into clearer focus in a few years' time, though, as NASA's New Horizons probe is due to make a close flyby of the dwarf planet in July 2015, marking the first time a spacecraft has ever visited the frigid, faraway world.
For now, though, here are the five strangest facts about the former ninth planet in our solar system.
Pluto used to be giant
Pluto and Charon as taken with the ESA/Dornier Faint Object Camera on Hubble Space Telescope in 1994. (Image credit: NASA/ESA)
When Pluto was discovered (by American Clyde Tombaugh in 1930), it was initially believed to be larger than Mercury, and possibly bigger than Earth. Now astronomers know that it's about 1,455 miles (2,352 kilometers) across less than 20 percent as big as our planet. And Pluto is just 0.2 percent as massive as Earth.
It doesn't fall in line
The planets of our solar system. (Image credit: NASA)
Pluto has an extremely elliptical orbit that's not in the same plane as the eight official planets' orbits. On average, the dwarf planet cruises around the sun at a distance of 3.65 billion miles (5.87 billion km), taking 248 years to complete one circuit .
It's strange orbit means that, for a few years at a time, Pluto's orbit overlaps with Neptune's. This brings Pluto closer to Earth than Neptune, the eighth planet from the sun. Don't worry, though, Pluto and Neptune won't collide .
A pair of small moons orbiting Pluto named Nix and Hydra were discovered by NASA's Hubble Space Telescope in 2005. The two moons are roughly 5,000 times fainter than Pluto and are about two to three times farther from Pluto than its large moon, Charon, which was discovered in 1978. (Image credit: NASA)
Because it's so far from the sun, Pluto is one of the coldest places in the solar system, with surface temperatures hovering around minus 375 degrees Fahrenheit (minus 225 degrees Celsius). Scientists think the dwarf planet is about 70 percent rock and 30 percent ice. Its surface is covered predominantly with nitrogen ice.
Once seen up close, Pluto's surface could turn out to have cold-liquid-belching cryovolcanoes or geysers. A giant underground ocean could exist as well, and clues to its presence could be inferred by the geology or chemistry of Pluto's surface.
Pluto has puppies
Two labeled images of the Pluto system, released on July 20, 2011, taken by the Hubble Space Telescope's Wide Field Camera 3 ultraviolet visible instrument with newly discovered fourth moon P4 circled. The image on the left was taken on June 28, 2011. The image of the right was taken on July 3, 2011. (Image credit: NASA, ESA, and M. Showalter (SETI institute))
Pluto has five known moons: Charon, Nix, Hydra and two newly discovered tiny satellites. While Nix, Hydra and the two new finds are relatively small, Charon is about half as big as Pluto.
Because of Charon's size, some astronomers regard Pluto and Charon as a double dwarf planet, or binary system the two bodies are gravitationally locked, and always present the same face toward each other as they orbit a common center of mass located somewhere between them.
Images of the dwarf planet Pluto taken by NASA's Hubble Space Telescope. CREDIT: NASA, ESA, and M. Buie (Southwest Research Institute)
Despite being smaller than Earth's moon, the dwarf planet has managed to hold on to a thin atmosphere composed mainly of nitrogen, methane and carbon monoxide that extends about 1,860 (3,000 km) into space.
Fun Facts About Pluto – AstroReality
How much do you know about Pluto? NASA’s New Horizons Spacecraft captured the first high-resolution photos of Pluto after it flew past in 2015. The mission provided amazing insight into the distant dwarf planet and its moon system.
Did you know that Pluto is actually smaller than some Moons? Or that Pluto was once considered our ninth planet before it was demoted in 2005?
If you’re looking to discover more fun facts about Pluto, read on below.
Discovery of Pluto
Pluto was originally discovered in 1930 by Lowell Observatory in Arizona. It was one of the first objects to be photographed in the Kuiper Belt, a large ring of debris circling the outer solar system.
The discovery of a new planet made global news, and it was actually named by an eleven-year-old girl in Oxford, United Kingdom, who had a keen interest in classical mythology.
The name “Pluto” refers to the ruler of the Underworld.
While Pluto was considered our ninth planet from the Sun, it came into a lot of controversy in the early 2000s.
Similar-sized objects were discovered in the Kuiper Belt, which led many to question the status of Pluto as a planet.
It wasn’t until astronomers discovered Eris in 2005, an object in the same region substantially larger than Pluto, that the International Astronomical Union (IAU) sought to redefine the term “planet.”
In 2006, the IAU released a new definition for a “planet” which stated that an object needed to;
- Orbit the Sun
- Not be a satellite of another object.
- Have large enough mass to be rounded by its own gravity.
- Clear small objects from its orbit (clearing the neighborhood).
While Pluto meets most of these characteristics, it doesn’t possess enough mass to clear debris from its orbital neighborhood. The planet was officially reclassified to a “Dwarf Planet” amid much controversy. There is still an ongoing debate among the scientific community, but at this stage, Pluto is now a Dwarf Planet.
Pluto Size and Surface
Pluto is one of the coldest places in our solar system and sits at a chilly -375 degrees Fahrenheit! Its surface consists of approximately 70% rock and 30% water ice, which is thought to be a mixture of frozen nitrogen, carbon monoxide, and methane. In fact, the planet has more than three times the amount of water than all of Earth’s oceans combined!
Pluto is quite small in comparison to other planets. The dwarf planet has a diameter of 1473 miles, which puts it at one-fifth of Earth’s diameter. Eris, the second-largest dwarf planet, is only fractionally smaller at 1,445 miles in diameter. In fact, Pluto is smaller than several moons, including Earth’s own Lunar.
Due to the distance from Earth, little was known about Pluto until 2015, when NASA’s New Horizons Spacecraft flew by at close range. The observations provided a lot of interesting features; from the mountain range of Norgay Montes that extends up to 11,000 feet, and the large heart-shaped region called Tombaugh Regio.
Moons of Pluto
The Dwarf Planet of Pluto has five natural satellites (moons); Charon, Styx, Nix, Kerberos, and Hydra. These are thought to have formed after Pluto collided with another object in the Kuiper Belt at the early stages of the solar system formation.
Pluto’s main Moon, Charon, is considerably large in comparison to its parent. Charon is nearly half the size of Pluto with a diameter of approximately 750 miles. Pluto and Charon are gravitationally locked, so the same side of each is always facing the other.
Nix and Hydra are two small moons discovered in 2005 by the Hubble Space Telescope. Both moons are similar in size at approximately 24 miles at the longest dimension and both tumble chaotically due to the elongated shape.
Discovered in 2011, Kerberos is a tiny irregular-shaped moon measuring approximately 7.5 miles at its longest point. Located between Nix and Hydra, scientists believe Kerberos is the result of a merger between two smaller objects.
Styx is a Pluto’s smallest Moon with a diameter measuring between 6 and 15 miles. Due to the size, there is not enough gravity to mold the Moon into a sphere, and as such has an irregular shape also. Scientists discovered Styx in 2012 after scouring the region for potential hazards that may impact the New Horizons Spacecraft mission.
Discover PLUTO with Augmented Reality
Combining a 3D printed model with augmented reality (AR), you can take participate in an interactive learning experience on Pluto!
Facts About Pluto | The Fact Site
- Pluto was first discovered in 1930 by an astronomer called Clyde Tombaugh.
- Pluto is a dwarf planet that lies at the very edge of our solar system.
- It takes the sunlight five and a half hours to reach Pluto, which is a lot, considering it only takes eight minutes to reach Earth.
- Pluto is only about two-thirds the size of our moon and is extremely cold, it is so cold that nitrogen and oxygen is frozen solid, its surface temperature is -233°C, so we’ve got no chance of living there!
It takes 247.
9 Earth years for Pluto to orbit the Sun once, which sometimes takes it inside Neptune‘s orbit.
Pluto makes a full rotation every 6.8 days.
It is approximately 5.9 billion kilometers (3.7 billion miles) away from the Sun. It has a diameter of 2,360 kilometers.
Pluto has a moon called Charon, which is roughly one half of the size of Pluto. Well, it also has two other moons which were discovered by the Hubble Space Telescope, these moons are called Nix and Hydra; these are named after the Greek goddess of darkness (Nyx) and a nine-headed serpent that in Greek mythology guards the underworld.
Is Pluto A Planet?
- I’ve been careful to not call Pluto a planet during this because Pluto is in fact not a planet.
- It was decided back in August 2006 when 2,500 scientists researched the official meaning of the word “Planet”.
- The researchers said “Pluto failed to dominate its orbit around the Sun in the same way as the other planets”.
- With the technology out there today, they have calculated the size of Pluto and say it’s not big enough to be called a planet, therefore it is known as a dwarf planet.
- If the vote went the other way that would mean there would be an extra 44 “planets” out there that have been discovered so far.
- That’d be hard to learn for school!
- So yeah, with Pluto being a dwarf planet, all that really means is in books, Pluto will not be categorised as one of the main planets in the solar system.
- Here’s the exact definition of a Planet, which was agreed by the 2,500 scientists at that meeting: – it must be in orbit around the Sun – it must be large enough that it takes on a nearly round shape
- – it has cleared its orbit of other objects
Interesting Facts about Dwarf Planet Pluto
Of all of the planets in our solar system that have been the topic of controversy and debate, Pluto is at the top of the list. Generations grew up thinking that Pluto was the ninth planet and then in 2006, they demoted little Pluto to become a dwarf planet.
- At one time, Pluto wasn’t just thought to be our ninth planet but was also thought to be the largest item in the Kuiper Belt which is located in the areas beyond Neptune’s orbit.
- It was so far out that even the most powerful telescopes of the time could only show Pluto as a fuzzy grey image.
- The Kuiper Belt is home to hundreds of thousands of icy, rocky objects, many bigger than 62 mi/100 km across and over 1 trillion or more comets.
- The demotion of Pluto outraged many in the scientific community as well as public opinion.
- There was a proposal of a new definition of “planethood” in 2017 that included scientists and members of the New Horizon spacecraft mission to include “round objects in space smaller than stars” as part of the classification criteria.
- This would change the number of planets in our solar system from the current eight to around one hundred.
- Discovered By: Clyde W. Tombaugh
- Date Discovered: February 18, 1930
- Diameter: 2,372 km
Mass: 1.31 × 10^22 kg (0.17 Moons)
- Orbit Distance: 5,874,000,000 km (39.26 AU)
- Orbital Period: 248 years
- Surface Temperature: -229 degrees C
- Moons: 5
Pluto is smaller than our moon and is a mysterious world that has valleys, plains, craters, and possibly glaciers. It has five moons and the biggest moon is Charon, which is almost half the size of Pluto.
Charon and Pluto are listed as a “double planet” because they orbit so close to each other. Charon is listed as the largest satellite relative to its parent planet in our solar system.
It is thanks to the New Horizon spacecraft that we have learned so much about Pluto and its complex geology.
In 1905, Percival Lowell, an American astronomer first discovered Pluto when he found strange deviations in the orbits of both Uranus and Neptune. These alterations in their orbits suggested that there was another object’s gravity that was tugging on them.
July 14, 2017: On July 14, 2015, NASA’s New Horizons spacecraft made its historic flight through the Pluto system – providing the first close-up images of Pluto and its moons and collecting other data that has transformed our understanding of these mysterious worlds on the solar system’s outer frontier.
Perspective view of Pluto's highest mountains, Tenzing Montes. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/ Lunar and Planetary Institute/Paul Schenk
Scientists are still analyzing and uncovering data that New Horizons recorded and sent home after the encounter. On the two-year anniversary of the flyby, the team unveiled a set of detailed, high-quality global maps of Pluto and its largest moon, Charon.
Pluto—which is smaller than Earth’s Moon—has a heart-shaped glacier that’s the size of Texas and Oklahoma. This fascinating world has blue skies, spinning moons, mountains as high as the Rockies, and it snows—but the snow is red.
“The complexity of the Pluto system — from its geology to its satellite system to its atmosphere— has been beyond our wildest imagination,” said Alan Stern, New Horizons principal investigator from the Southwest Research Institute in Boulder, Colorado. “Everywhere we turn are new mysteries.”
- Go farther. Explore Pluto In Depth ›
- 10 Things to Know About Pluto
Pluto is about 1,400 miles (2,380 km) wide. That's about half the width of the United States, or 2/3 the width of Earth's moon.
Pluto orbits the Sun about 3.6 billion miles (5.8 billion km) away on average, about 40 times as far as Earth, in a region called the Kuiper Belt.
A year on Pluto is 248 Earth years. A day on Pluto lasts 153 hours, or about 6 Earth days.
Pluto is officially classified as a dwarf planet.
Pluto has a thin atmosphere of nitrogen, methane and carbon monoxide. The atmosphere has a blue tint and distinct layers of haze.