Discover 2 new moons belonging to Pluto

Using the Hubble Space Telescope to observe the solar system's edge, astronomers discovered two more small moons flying around the orbit of Pluto, bringing the planet's satellites to numbers. 3.

Pluto is in the KuiPer belt, a ring containing ice fragments outside Neptune's orbit, created by the formation of the Solar System. Previously, it was thought that Pluto was a lone star when it was discovered in 1930 and considered the 9th planet in the Solar System. However, in 1978, its first satellite was discovered, Charon .

The two new moons of Pluto, roughly named S / 2005 P1 and S / 2005 P2, are about 5,000 times more faint than Pluto. P1, with a diameter of about 55 - 160 km, larger than P2 about 20%, P2 has a relatively small size and has a diameter of about 45 - 180 km.

Scientists calculate the size of these satellites thanks to the amount of light they reflect. However, they could not give a more accurate figure because they were unsure whether the surface of these moons was covered with ice, solid hydrocarbons or something else.

Hal Weaver of Johns Hopkins University, a member of the research team who discovered the moons, said: " At first I couldn't believe it. People have been searching for satellites of Pluto for a long time. already ".

The team discovered the satellites for the first time on May 15. Subsequent observations proved that they flew around the Pluto's orbit with a distance of twice as long as Charon.

P2 is about 49,000 km from Pluto and takes about 25.5 days to fly around the planet. And P1 is farther away, about 65,000 km and its orbit lasts 38 days.

"This is the first time we have known an object in the Kuiper belt with many satellites," Weaver said. This discovery will help astronomers study the formation of the Pluto-Charon planetary system.

Charon is a relatively large moon compared to its parent planet, about the size of about 15% of Pluto. By comparison, our moon only weighs about 1.2% of the Earth.

Some astronomers believe that Pluto could have acquired its enormous moon after colliding with another young planet, creating a fragment and becoming Charon.

Although the new discovery does not confirm this prediction, Weaver argues that due to the fact that the moons are on the orbit of a planet with Charon, it is possible that they will appear at the same time.

However, P1 and P2 can also be merely objects from the Kuiper belt that Pluto draws.

Hubble telescope

The recent improvements of the telescope have helped astronomers discover a wealth of new things about Kuiper belt objects. Earlier this year, the discovery of planetary 2003 UB313, which was larger than Pluto and farther away from the Sun, again sparked controversy over whether Pluto should be considered an act. crystal or not.

So does this star have any more satellites in the shadow-covered area? Another member of the research group, Andrreu Steffl, said: "The pictures Hubble obtained were the most subtle findings to date about objects around Pluto and there seems to be no longer any satellite. Bigger size 16km flying around this star ".

Nature