At the edge of our solar system sits lonely, the dim planetary object known as DeeDee. First time spotted in 2014 and officially discovered in late 2016, astronomers didn’t have enough data about its physical structure. Finally, new data from the Atacama Large Millimeter/Submillimeter Array (ALMA) has revealed details about the mysterious object’s true identity.

A new world  in our own cosmic backyard

Back in 2014 by using the optical Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile astronomers have spotted for the first time the far-flung object. This new face in our solar system family was called 2014 UZ224 but is far more known as DeeDee, which stands for Distant Dwarf.

Blanco telescope was only able to determine the object’s orbit. The object loops around the sun on a highly elliptical path about 92 AU, which means it takes more than 1,100 Earth years to complete one orbit. It makes it the second most distant known trans-Neptunian object (TNO).

Size comparisons of objects in our solar system, including the recently discovered planetary body. Credit: Alexandra Angelich (NRAO/AUI/NSF)

Thanks to the new data release of ALMA, we have physical measurements of our distant neighbor. Alma is an international observatory that seeks to find new information not only about the Solar System but the entire universe as well. It is powered by a single, yet very powerful, high precious telescope and is considered as one of the largest astronomical projects in the world.

Since ALMA observes the cold, dark universe, it is able to detect the heat in the form of millimeter-wavelength light. The heat signature of a distant solar system object would be directly proportional to its size. Using DeeDee’s heat signature, the astronomers were able to confirm that DeeDee was uncommonly large but so dark that it only reflected about 13 percent of the sunlight that reached it.

ALMA image of the faint millimeter-wavelength “glow” from the planetary body 2014 UZ224, more informally known as DeeDee. At three times the distance of Pluto from the sun, DeeDee is the second most distant known TNO with a confirmed orbit in our solar system. Credit: ALMA (ESO/NAOJ/NRAO)
Orbits of objects in our solar system, showing the current location of the planetary body ‘DeeDee.’ Credit: Alexandra Angelich (NRAO/AUI/NSF)

Also, it is confirmed that DeeDee is about two-thirds the size of the dwarf planet Ceres, the largest member of our asteroid belt, and has enough mass to be spherical. This means DeeDee fulfills the criteria necessary to be termed a dwarf planet, although astronomers have yet to give it that official label.

Obviously, the solar system is a rich and complicated place full of cold mysterious worlds. Thanks to advanced technology, we can only imagine what kind of objects we will discover in the future. The researchers note that these same techniques could be used to detect the hypothesized ‘Planet Nine’ that may reside far beyond DeeDee and Eris.