The faraway dwarf planet 2007 OR10, nicknamed "Snow White," is bigger than previously believed, a study found. The new measurements make Snow White the third biggest dwarf planet in our solar system.
Snow White was previously measured to have a diameter of 795 miles. Researchers used NASA's Kepler space telescope - the repurposed mission is now called K2 - and poured over archived data from the Herschel Space Observatory to arrive at a new figure for Snow White's size: 955 miles in diameter.
The new study, which was published in The Astronomical Journal on April 19, also discovered that Snow White, regardless of its name, is darker than previously observed. Moreover, Snow White rotates more slowly compared to other stellar bodies rotating the sun - it takes close to 45 hours to complete its daily spin.
Kepler/K2 research scientist Geert Barentsen noted K2's vital contribution to the size estimates of Snow White. What's more important, he said, is how the combination of K2 and Herschel data was able to produce new information about Snow White's physical properties.
The Kepler telescope enabled the team to analyze the sunlight fraction reflected by Snow White while the Herschel telescope allowed them to measure the fraction that was absorbed and radiated back.
The combination of the two sets of data allowed them to estimate the dwarf planet's size and its reflective figures. The larger size also suggested that Snow White has a higher gravity.
Moreover, its darker nature makes it quite different from the majority of dwarf planets in the solar system that are often brighter.
"Our revised larger size for 2007 OR10 makes it increasingly likely the planet is covered in volatile ices of methane, carbon monoxide and nitrogen, which would be easily lost to space by a smaller object," said lead researcher András Pál from the Konkoly Observatory in Hungary.
The U.S. space agency recently published a new video of the dwarf planet along with its new measurements. The only two bigger objects of its kind are Eris (1,445 miles) and Pluto (1,475 miles).
The fourth and fifth biggest are the oblong-shaped Haumea (1,195 miles) and Makemake (890 miles).