Dr Sheppard, from the Carnegie Institution for Science in Washington and Dr Trujillo, from Northern Arizona University, have been analysing how the new planet-like bodies fit into larger theories about a ninth planet lurking in the Solar System’s furthest reaches. The evidence for this planet has largely been deduced by peculiarities of distant Solar System objects. One of the new celestial bodies, 2013 FT28, shares characteristics of its orbit in common with the bodies whose positions and movements lent support to the planet nine idea – but it also shows some differences. Based on analysis of other small bodies in the outer Solar System, astronomers have proposed that – if it exists – the ninth planet is several times more massive than Earth and is at least 200 times further than the distance between the Sun and Earth. The new work should help constrain the location of this proposed ninth planet. “The smaller objects can lead us to the much bigger planet we think exists out there,” said Dr Sheppard. “The more we discover, the better we will be able to understand what is going on in the outer Solar System.” Pluto, discovered in 1930, was previously known as the ninth planet. But its planetary status was removed in 2006, following the discovery of an object of comparable size in the Kuiper Belt, a ring of icy bodies just beyond Neptune.

lurk: v. 潜伏

deduce: v. 演绎,推断,溯源

peculiarities: n. 古怪

celestial: adj. 天的, 天空的

constrain: v. 强迫; 限制