A billion miles past Pluto, in the furthest area of the solar system, lies an object called Ultima Thule. His name means "outside the known world."
Although scientists have detected it with a telescope, they don't know much about it. What they have obtained from their observations is that Ultima Thule is a rock in the Kuiper belt of the solar system, an area outside Neptune. The shape is irregular and about 18 miles wide. This might look like two potatoes that have been clamped together, like:
On January 1, the New Horizons spacecraft, famous for flying by Pluto, will pass Ultima Thule to explore this strange rock and try to learn more about the formation of our solar system.
After the New Horizon flew past Pluto in 2015, its mission scientists chose Ultima Thule as the next stop in the Kuiper belt, mainly because the New Horizon had the ability to achieve it with the remaining fuel.
But the New Year's crossing is very important because Ultima will be the furthest object in the solar system humans have explored, and one of the most primitive.
Because Ultima is in a cold, remote and quiet area of the solar system, it may orbit the sun without interruption for almost the entire solar system.
"We hope that Ultima is the most preserved sample of a planetary building block ever explored," wrote Alan Stern, principal researcher at New Horizons, writing in a blog post. "What will Ultima say? No one knows. For me, that's the most interesting thing – this is pure exploration and fundamental science! "
For Stern, shortcuts – and pictures from there – would be similar to the famous "Earthrise" photo taken by the Apollo 8 mission 50 years ago. This photo was taken the first time humans orbit the moon. It was the first time we saw our own planet from another world perspective.
"Over the years between Apollo 8 December exploration and us, NASA has made history exploring even further," wrote Stern. "As a result, we have made Carl Sagan's prediction that in just one or two generations the planet will change from light points to the real world and be explored."
For now, Ultima Thule is still a bright spot. This is how the New Horizons camera looks, as the spacecraft approaches closer.
But soon it will be more than one bright spot. The image of the object may be dimmer than the image of Pluto (this is a billion miles further than the sun). But New Horizons has a camera that can see amazing fine details. Just look at the picture taken from Pluto.
Remember that Pluto was just a bright spot too. New Horizons reveals it as an extraordinary world, dynamic with beautiful heart shaped ice planes. This GIF shows the best Pluto image that we have had since 2015, turning into what New Horizons saw on its historic journey. It changed from dirty lumps to something beautiful.
(And yes, scientists are still debating whether Pluto is worthy of being named a planet, not a dwarf planet.)
The new horizon will pass ultima thule around east 12:33 on January 1, immediately after the start of the new year. You can follow with NASA on NASA TV live broadcasts (see below). New Horizons will also carry messages from the public (delivery ends on December 21) to celebrate a distant arrival.