Using the Hubble Space Telescope to observe the edge of the Solar System, astronomers have discovered two small moons orbiting Pluto, bringing the total number of its satellites to three.
Pluto is located in the Kuiper Belt, a region filled with icy debris beyond the orbit of Neptune, formed during the early stages of the Solar System. Initially, when Pluto was discovered in 1930, it was thought to be a solitary body and was considered the ninth planet of the Solar System. However, in 1978, its first moon, Charon, was discovered.
The two newly discovered moons of Pluto, temporarily named S/2005 P1 and S/2005 P2, are about 5,000 times dimmer than Pluto. P1 has a diameter ranging from 55 to 160 kilometers and is approximately 20% larger than P2, which is relatively smaller, with a diameter between 45 to 180 kilometers.
Scientists estimated the sizes of these moons based on the amount of light they reflect. However, they cannot provide a more precise measurement because it is uncertain whether the surfaces of these moons are covered in ice, solid hydrocarbons, or other materials.
Hal Weaver from Johns Hopkins University, a member of the research team that discovered these moons, stated: “At first, I couldn’t believe it. People have been searching for Pluto’s satellites for a long time.”
The research team first identified these satellites on May 15. Subsequent observations confirmed that they orbit Pluto at a distance twice that of Charon.
P2 is located approximately 49,000 kilometers from Pluto and takes about 25.5 days to complete its orbit around the planet. P1 is located even further away, about 65,000 kilometers, with an orbital period of 38 days.
Weaver remarked: “This is the first time we have known of an object in the Kuiper Belt with multiple satellites.” This discovery will aid astronomers in studying the formation process of the Pluto-Charon system.
Charon is a relatively large moon compared to its parent planet, measuring about 15% the size of Pluto. In comparison, our Moon is only about 1.2% the size of Earth.
Some astronomers believe that Pluto may have acquired its massive moon after colliding with another young planet, creating debris that formed Charon.
Although the new discovery does not confirm this hypothesis, Weaver suggests that since the moons share an orbit with Charon, they likely formed around the same time.
However, it is also possible that P1 and P2 are merely objects from the Kuiper Belt that Pluto captured.
 |
Hubble Telescope |
Recent advancements in the telescope have allowed astronomers to uncover numerous new findings about Kuiper Belt objects. Earlier this year, the discovery of the planet 2003 UB313, which is larger than Pluto and further from the Sun, reignited the debate over whether Pluto should still be considered a planet.
So, does this celestial body have any additional satellites hidden in the shadows? Another team member, Andrreư Steffl, stated: “The images captured by Hubble represent the most subtle discovery to date of objects surrounding Pluto, and it seems there are no other satellites larger than 16 kilometers orbiting this planet.”
Nature
