Washington: New Horizons mission scientists have found Pluto to be 1,473 miles (2,370 kilometers) in diameter, slightly larger than many prior estimates.
The accurate estimation was made using images acquired with the Long Range Reconnaissance Imager (LORRI) on NASA's New Horizons probe.
The result confirms that Pluto is larger than all other known solar system objects beyond the orbit of Neptune.
Thus, NASA's New Horizons probe, set to zip past the dwarf planet on Tuesday, has answered one of the most basic, yet debated questions about Pluto - its size.
Pluto’s newly estimated size means that its density is slightly lower than previously thought, and the fraction of ice in its interior is slightly higher. Also, the lowest layer of Pluto’s atmosphere, called the troposphere, is shallower than previously believed, said NASA.
“The size of Pluto has been debated since its discovery in 1930. We are excited to finally lay this question to rest,” said mission scientist Bill McKinnon, Washington University, St Louis.
New Horizons' observations of Pluto's largest moon Charon also confirm previous estimates of 751 miles (1208 kilometers) across.
LORRI has also zoomed in on two of Pluto’s smaller moons, Nix and Hydra.
The New Horizons probe will make its closest approach to the icy planet at 7:49:57 am EDT today (July 14).
NASA's New Horizons mission will help scientists understand worlds at the edge of our solar system by making the first reconnaissance of the dwarf planet Pluto and by venturing deeper into the distant, mysterious Kuiper Belt - a relic of solar system formation.