New data about two distant asteroids give a clue to the possible ‘Planet Nine’

Proposed path of Planet 9 around the sun with Neptune and several notable TNOs for reference [credit: Wikipedia]

Researchers suggest the pair may have got too close to the hypothetical Planet Nine, resulting in their current orbits.

The dynamical properties of these asteroids, observed spectroscopically for the first time using the Gran Telescopio CANARIAS, suggest a possible common origin and give a clue to the existence of a planet beyond Pluto, the so-called ‘Planet Nine’, reports Phys.org.

In the year 2000 the first of a new class of distant solar system objects was discovered, orbiting the Sun at a distance greater than that of Neptune: the “extreme trans Neptunian objects” (ETNOs). Their orbits are very far from the Sun compared with that of the Earth.

We orbit the Sun at a mean distance of one astronomical unit (1 AU which is 150 million kilometres) but the ETNOs orbit at more than 150 AU. To give an idea of how far away they are, Pluto’s orbit is at around 40 AU and its closest approach to the Sun (perihelion) is at 30 AU. This discovery marked a turning point in Solar System studies, and up to now, a total of 21 ETNOs have been identified.

Recently, a number of studies have suggested that the dynamical parameters of the ETNOs could be better explained if there were one or more planets with masses several times that of the Earth orbiting the Sun at distances of hundreds of AU.