The target was 2014 MU69, or popular name: Ultima Thuli (in Latin: “Beyond the Limits of the Known World”). This object has been in the deep freeze of the solar system for 4.5 billion years, so scientists hope to learn new insights into the formation of the system. But as the spacecraft approaches it, and the data on it is improving, it is clear that something is not happening there.

The New Horizons team concluded that the bone, about 37 kilometers wide, is not a spherical object but rather elongated, in fact the bone may not be a bone at all – but a binary system of two objects surrounding it If the object was elongated, or composed of two separate or adjacent objects, we would expect to see a change in the reflected light curve as it rotated along its axis, depending on the angles assigned to the New Horizons spacecraft.

Instead, mission scientists have been discovering in recent days that Altima Thule’s clarity is relatively consistent, like the brightness of a globular body. One possibility is that the axis of the elongated or binary body (its pole, for that matter) in the case directly addresses the probe, so it does not recognize the changes in brightness in the rest of the body. Another possibility is that Oltima Thuli is surrounded by a cloud of dust, like the tail of a comet, that blocks and diffuses the light absorbed by the spacecraft. But comets “get” such a tail only when they approach the sun, which boils frozen materials to the gases – while Ultima Thuli is a frozen object and very far from the sun. And even more strange is that the small object is surrounded by a multitude of tiny moons. It should be noted that all the options currently being discussed will constitute a precedent in space exploration.

“This is a real riddle,” Allen Stern, the mission’s lead investigator, told the press. “We expected to find many riddles on our visit to Ultima Thuli, but we did not expect the light to be one of them, and for all the ideas suggested for solving the light curve puzzle, it’s hard to know which idea turns out to be true.