Pluto has a new buddy: astronomers at the University of Michigan have spotted a new dwarf planet lurking in the outskirts of the Solar System. Dubbed DeeDee, short for ‘distant dwarf’, the planet is between 320km and 1,290km in diameter and is currently more than 13.6 billion kilometres from the Sun, making it the one of the most distant minor planets ever seen.
It was found using DECam, a powerful digital camera on a four-metre telescope in Chile that’s capable of picking up extremely faint signals. The reflected sunlight detected from DeeDee is as dim as the light from a single candle observed from 160,000km away.
The researchers say the discovery of this icy, faraway world shows that their method has potential for finding Planet Nine – a massive body hypothesised to reside around 600 times farther from the Sun than Earth does.
“The discovery of DeeDee is a promising sign of our ability to find distant new worlds,” explained lead researcher David Gerdes. “If more things like this are in our data, the tools we’ve built will find them.” To identify the planet, the team fed thousands of images into a computer programmed to find objects moving in orbit around the Sun, against the background of millions of stars and galaxies that remain in the same place from night to night.
“Every image taken by DECam is subtracted from every other image from the same piece of the sky. That way, we can find moving Solar System objects even if they happen to lie right in front of a background galaxy or star,” said researcher Masao Sako.