The most sophisticated telescopes discover galaxies millions of light-years away. Kepler sees exoplanets hundreds of light-years away. Yet, our solar system holds secrets only now being uncovered. Before NASA’s New Horizons blew us away with pictures of Pluto, the best we had was this fuzzy image from the Hubble Space Telescope.
A few days ago, a group of astronomers shined a light on another small world far beyond Neptune. It doesn’t have a name, but its official designation is 2007 OR10.
Understanding a world like 2007 OR10 brings many challenges. The biggest issue is light. Those galaxies dating back to just after the Big Bang? Most of them are incredibly bright. Same goes for exoplanets orbiting bright stars. But a tiny world orbiting in the far reaches of the solar system is tough to spot.
The team of astronomers needed the combined power of two telescopes – Kepler and Herschel. Kepler’s extreme sensitivity to changes in brightness was vital to understanding the dwarf planet. Here’s a short video showing 2007 OR10 as it moves among the stars.
But Kepler’s observations were not enough for astronomers to figure out the size of the dwarf planet. Astronomers needed to know if the light seen by Kepler was a small, bright object, or a large, dark object. And that’s where Herschel comes in. While Kepler measured the amount of sunlight reflected by 2007 OR10, the Herschel Space Observatory observed the amount being absorbed and radiated back as heat.
Did You Know: 2007 OR10 was first discovered in 2007 and given the nickname ‘Snow White.’ But the dwarf planet is actually a deep red and is likely covered in layers of volatile ices of methane, carbon monoxide and nitrogen.
Earlier estimates of 2007 OR10 (with Herschel data only) suggested the world was about 795 miles across. With the combined data of Kepler and Herschel, astronomers now say the dwarf planet is 995 miles across. That places it number 3 on the list of largest dwarf planets behind Pluto and Eris. Its diameter is about 60 miles larger than Makemake.
“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 András Pál at Konkoly Observatory in Budapest, Hungary, who led the research. “It’s thrilling to tease out details like this about a distant, new world — especially since it has such an exceptionally dark and reddish surface for its size.”
Other interesting findings include:
– A day (one spin on its axis) on 2007 OR10 takes 45 hours. It’s not the slowest day in our solar system, but it is slower than many other planets. Venus holds the record for the longest day of any planet at 243 Earth days for one rotation.
– The “exceptionally dark surface” is believed to be the result of methane ices on its surface. New Horizons’ close encounter with Pluto showed the world that distant dwarf planets aren’t drab, icy worlds. They’re icy, but they are most certainly not drab. Pluto stunned, but you can you imagine what a probe would see on a flyby of 2007 OR10?
With such a stunning world, when will it shake its 2007 OR10 designation? That honor belongs to discovering astronomers Meg Schwamb, Mike Brown and David Rabinowitz.
“The names of Pluto-sized bodies each tell a story about the characteristics of their respective objects. In the past, we haven’t known enough about 2007 OR10 to give it a name that would do it justice,” said Schwamb. “I think we’re coming to a point where we can give 2007 OR10 its rightful name.”
This week’s research shows just how much data astronomers have at their fingertips. The Kepler data used here came from K2 mission’s Campaign 3 in late 2014. Today, Kepler is busy gathering data for Campaign 9. This mission is a little different as Kepler will use gravitational microlensing to search for planets wandering that aren’t close to their stars.