For over 70 years, scientists have been predicting the existence of a certain type of object in the outer Solar System. Small in size, these potential bodies are thought to constitute an important early step in the planet formation process
Since these hypothetical objects are between 1 and 10 kilometers in radius (0.6 to 6.2 miles), it's tricky to spot them from where we sit. But now astronomers think they have done it.
By staring at the sky for hours, they have obtained evidence of an object just 1.3 kilometers (1.3 miles) in radius, near Pluto's orbit. The find could be a representative of this proposed class of small, kilometer-sized Kuiper Belt objects.
Given their small size and dimness, the objects can not be seen directly. Astronomers from the National Astronomical Observatory of Japan tried another method ̵
The work paid off – the team found evidence of a tiny point called a planettesimal orbiting the Sun at a distance of 32 astronomical units (AU). This actually places it within Pluto's orbital range, which is between 29 and 49 AU
This is the first time that one of these planetesimals has been detected, the researchers said – and it's a marvelous feat, considering the distances involved and the tools used
"This is a real victory for little projects. "We did not even have enough money to build a second dome to protect our second telescope, but we still managed to make a discovery that is impossible for big projects," said NAOJ astronomer Ko Arimatsu
We do not know for sure how the planet formation works, but according to current hypotheses, it goes a little like this
After a star is born, it is surrounded by a disc of leftover dust and gas swirling in its orbit. Electrostatic forces begin to bind particles in this protoplanetary disk to each other, building a clump; as clump gets bigger, its gravitational force grows too, which collects more and more particles, growing the clump even more
We have seen these discs around other stars using radio astronomy, and even a picture of what astronomers think is and Planing
Here is a bit closer to home, in our Solar System, the Kuiper Belt – a wide disk of rock and ice bodies outside the orbit of Neptune – is thought to be a remnant of our early Solar System. It contains larger bodies, including dwarf planets such as Pluto (2,377 kilometers or 1,477 miles) and 2014 MU69 (31 kilometers, or 19 miles).
Because they are protected by ice and away from Sun's radiation, these bodies are thought to be time capsules, preserving the conditions of the Solar System's formation. And those objects between 1 and 10 kilometers are thought to be evidence of the point between the initial electrostatic aggregation of dust and the snowballing gravitational growth.
This discovery, using relatively cheap telescopes on a rooftop in Japan, means that it's likely these plantesimals are more abundant than previously thought – a nice piece of evidence that our planet-forming formation is on the right track.
And the team is not done yet. "
" Now that we know our system works, we will investigate the Edgeworth-Kuiper Belt in more detail, "Arimatsu said. "
The team's research has been published in the journal Nature Astronomy .