Published: 31st Mar, 2022
Context
Scientists Discover 'Unique' Ice Volcanoes on Dwarf-Planet Pluto's Surface.
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What melts the ice?
- Ice, of course, melts at much lower temperatures than rock.
- And when there is a mixture of two ices, melting can begin at a lower temperature than for either of the pure ices (the same principle applies in silicate rock made of different minerals).
- This makes melting even easier. Despite this, it is a surprise to find evidence of relatively young water-rich cryovolcanic eruptions on Pluto, because there is no known heat source to power them.
- There is only very limited scope for Pluto’s interior to be heated by tidal forces — a gravitational effect between orbiting bodies, such as a moon and a planet — which warm the interiors of some of the moons of Jupiter and Saturn. And the amount of rock inside Pluto is not enough to produce much heat from radioactivity.
New Horizons mission:
- New Horizons is a NASA mission to study the dwarf planet Pluto, its moons, and other objects in the Kuiper Belt, a region of the solar system that extends from about 30 AU, near the orbit of Neptune, to about 50 AU from the Sun.
- It was the first mission in NASA’s New Frontiers program, a medium-class, competitively selected and principal investigator-led series of missions. (The program also includes Juno and OSIRIS-REx.)
- New Horizons was the first spacecraft to encounter Pluto, a relic from the formation of the solar system. By the time it reached the Pluto system, the spacecraft had traveled farther away and for a longer time period (more than nine years) than any previous deep space spacecraft ever launched.
Why is Pluto not a Planet?
- As per the third condition, if an object ventures close to a planet’s orbit, it will either collide with it and be accreted, or be ejected out.
- But, in case of Pluto, it is affected by Neptune’s gravity.
- It also shares its orbit with the frozen objects in the Kuiper belt.
- Based on this, the IAU deemed that Pluto did not ‘clear its orbit’ (the third rule).
- Hence, it was designated a dwarf planet.
Dwarf Planets
- According to the International Astronomical Union (IAU), which sets definitions for planetary science, a dwarf planet is a celestial body that - orbits the sun, has enough mass to assume a nearly round shape, has not cleared the neighborhood around its orbit and is not a moon.
- The first five recognised dwarf planets are Ceres, Pluto, Eris, Makemake and Haumea.
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