NASA’s New Horizons probe has found evidence at the edge of the solar system that the so-called Kuiper belt is significantly larger than previously thought, or is even enclosed by another belt. The telltale traces were found using the Venetia instrument for counting dust particles. This should actually measure a decrease in this concentration after about one and a half billion kilometers in the Kuiper Belt, but this is not the case much further out. The measurements would fit with results from other studies that suggest the Kuiper Belt is much larger, or is surrounded by a similar structure.
Advertisement
Also other hints
The Kuiper Belt is a ring-shaped structure made up of different sized celestial bodies that is located behind Neptune. Currently thought to be at about 50 Astronomical Units (AU), the outer limit is now 58 AU from the Sun. The dust data was collected between 45 and 55 AU. The material counted with the Venetia Burney Student Dust Counter is due to collisions between celestial bodies and is therefore considered an indirect indication of their number. The research team writes that telescopes such as the Subaru Telescope are now discovering more and more large objects that orbit behind the assumed boundary of the Kuiper Belt. That matches the data from New Horizons.
If the data are confirmed, New Horizons could become the first space probe to discover a new population of celestial bodies in the solar system, says chief scientist Alan Stern from the Southwest Research Institute. The Voyager probes, for example, are significantly further away from the sun than New Horizons, but they do not have comparable instruments. Only the probe, which was built primarily to explore Pluto, can now analyze the dust far behind Neptune and Pluto. Every single measurement could lead to a discovery, says Alex Doner from the University of Colorado Boulder. Venetia was developed and built by students there. The research article on the dust measurements appeared in The Astrophysical Journal Letters.
New Horizons was launched 18 years ago and on July 14, 2015 was the first probe ever to pass Pluto, which had since been downgraded to a dwarf planet. There she revealed a surprisingly complex world. Later it became the first human-made object to reach a celestial body in the Kuiper Belt – the two-part Arrokoth. Since then it has not had a new target, but is still on its way out of the solar system. Most recently, the probe helped, among other things, to make the largest parallax measurement in history and to analyze the background brightness of the universe. That in itself caused a surprise.
(mho)