8.5 billion miles away from the Sun sits a cold world bathed in darkness. Known as 2014 UZ224, it’s the latest dwarf planet to be discovered in recent years. Scientists find planets far beyond our solar system all the time (2,700+ confirmed by Kepler), yet we are still finding dwarf planets in our solar system. And more are lurking beyond the orbit of Neptune. Why?
There are a few reasons. The biggest is size. Nearly all of the exoplanets discovered are massive. The term ‘super-Jupiter’ was coined for a reason. On the flip side, dwarf planets beyond Neptune are tiny specs of ice compared to the behemoths in other solar systems.
Let’s take a deeper look at 2014 UZ224. Scientists in Michigan made the discovery of the new dwarf planet and estimated it’s about 330 miles across. For comparison, Pluto is about 1,475 miles across. In fact, 2014 UZ224 doesn’t approach the biggest dwarf planets meandering through the Kuiper Belt.
NPR has a great piece about 2014 UZ224 and the person who helped make the discovery, David Gerdes (University of Michigan). Gerdes helped develop a special camera called the Dark Energy Camera that was commissioned by the U.S. Department of Energy to make a map of distant galaxies. Or, map the Upside Down. You’re not fooling anyone, Department of Energy.
Gerdes describes the challenge of calculating the orbit of the newly discovered dwarf planet.
“We often just have a single observation of the thing, on one night,” Gerdes tells NPR. “And then two weeks later one observation, and then five nights later another observation, and four months later another observation. So the connecting-the-dots problem is much more challenging.”
Gerdes and his colleagues developed software to help connect these dots across the night’s sky. The result? 2014 UZ244 takes 1,100 years to complete one orbit.
Which brings us to another reason why dwarf planets are tough to spot. Distance. You can see just how much further out this dwarf planet is compared to Pluto by looking at the orbital period. Pluto takes 248 years to make one trip around the Sun. 2014 UZ224 takes four times as long.
Objects in the Kuiper Belt often have highly elliptical orbits. Take another recently discovered dwarf planet, 2007 OR10. At perihelion (closest point to the Sun), it sits about 33 AU from the Sun. (1 AU is equal to the distance between the Earth and Sun). At aphelion (furthest point from the sun), it sits about 100 AU away.
When dwarf planets are at their furthest point, even today’s most powerful telescopes struggle to see them. Here’s how NASA’s Kepler telescope saw 2007 OR10 in late 2014.
Some objects orbit even further out. Sedna takes more than 10,000 years to complete one orbit around the sun. And it never enters the outer boundary region of the Kuiper Belt (located 55 AU from the Sun). It’s believed to be the first observed object of the inner Oort Cloud.
What’s next for dwarf planets?
It’s like anything in astronomy. Bigger telescopes. Better technology. More sophisticated techniques. The biggest dwarf planets are believed to be mostly accounted for. But there are still many smaller chunks of round ice waiting to be discovered. And if Pluto taught us anything, it’s these worlds are much more stunning than we could ever imagine.
New Horizons will give us our first look at one of these smaller objects on January 1, 2019, when it soars past 2014 MU69.