Now that NASA’s New Horizons spacecraft has successfully flown past Ultima Thule, which is the farthest celestial body that humans have explored so far with a distance of four billion miles separating it from Earth, scientists are now searching hard to determine whether it may also host moons.
With their historic fly-by, scientists have now learned that Ultima Thule stretches 21 miles in length and features two lobes which are shaped very much like spheres. Although these two objects were once completely separate and independent of each other, they gradually ended their autonomous journeys by flying towards one another and eventually linked up to form the snowman body we see today. As Live Science reports, with the first sphere called “Ultima” and the second “Thule,” data originally showed the pair completing one full rotation over a period of just four hours, at least when they first joined up with each other.
However, the rotation time of Ultima Thule is now known to take 15 hours, and according to Mark Showalter from the SETI (Search for Extraterrestrial Intelligence) Institute, this has scientists mightily confused. Showalter believes that perhaps the best explanation for this dramatic change is if Ultima Thule has one or more moons.
“So, how did they slow down? Well, the best way to understand that is if there were another moon, or two or three, orbiting this system. Essentially, what those moons would do is put the brakes on the two bodies in the middle — slow them down.”
— Live Science (@LiveScience) January 5, 2019
Scientists have so far not discovered any moons that are 500 miles or more away from Ultima Thule, nor have they found any 100 miles or closer. Yet this still leaves a sizeable region in the middle for them to search in, and this area is currently a huge mystery to scientists. The mystery won’t last forever, however, as towards the end of January New Horizons will dutifully be sending data back to scientists which will allow them to learn more about this middle area.
According to Showalter, this middle region around Ultima Thule also happens to be the most obvious spot to search for moons, and he is cautiously optimistic that at least one moon will turn up here.
“Any moon at all, on any orbit at all, will tell us the mass and the density to pretty decent usable precision. And so we’re very, very excited about that prospect.”
If it turns out that Ultima Thule has no moons after all, this doesn’t mean that they never existed as it is fully possible that these moons may have eventually drifted off into the vastness of deep space.