Astronomers spotted a Trans-Neptunian Object which reinforces the hypothesis of a Planet Nine in the outer solar system. Sorry, Plutonians, we’re not talking about your icy planetoid.
Thanks to Kepler telescope, astronomers have discovered and catalogued thousands of exo-planets in the Milky Way. So, surely we’ve found all of the planets in our own solar system, right?
Wrong. Or, at least, we’re not sure yet.
Ancient astronomers identified five planets: Mercury, Venus, Mars, Jupiter, and Saturn.
Then, in the 16th century, the Earth itself was recognized as a planet within Copernicus’ heliocentric system–orbiting the Sun with other 5 planets.
Since then, only three other planets were discovered: Uranus (1781), Neptune (1846), and last, Pluto (1930).
Our Solar System Might be way Larger Than we Think
Pluto enjoyed its status as the ninth planet up until a little over a decade ago (2006), when astronomers decided to downgrade it.
Pluto has become the representative of a new class of objects in the Kuiper belt called “dwarf planets”, or Trans-Neptunian Objects (TNOs).
Though they couldn’t observe it directly, planetary scientists still believe there’s a ninth planet, and mounting evidence suggests it’s there in the far outer solar system.
In 2016, two astronomers at the California Institute of Technology (Caltech) – Konstantin Batygin and Mike Brown – found several elements that support the existence of Planet Nine.
The shadowy Planet Nine is thought to have an orbit about 20 times farther away than that of Neptune, which is 4.5 billion kilometers away from the Sun.
It would therefore make a tour around the Sun once every 10,000-20,000 years.
With an estimated ten Earth masses, this candidate Planet Nine, according to researchers, could explain the eccentric orbits of several objects in the Kuiper belt.
The work of Batygin and Brown officially launched the hunt for Planet Nine.
How “Caju” Gives Away Planet Nine?
Now, scientists say the extreme orbit of a distant Trans-Neptunian Object, referred to as Caju, can be explained by the gravitational influence of a large planet in the solar system.
Astronomers first spotted evidence of Caju, aka 2015 BP519, in 2014, thanks to data from the Dark Energy Survey, a project that’s not intended for planet hunt in the first place.
At 55 AU (1 Astronomical Unit = distance between Earth and the Sun), Caju is located far away behind the orbit of Neptune, and has a very elliptical orbit that’s almost perpendicular to the plane of the solar system.
Such an extreme orbit could be due to the gravitational influence of a large planet–our hypothetical Planet Nine.
“… 2015 BP519 displays rich dynamical behavior, including rapid diffusion in semi-major axis and more constrained variations in eccentricity and inclination. We also consider the long term orbital stability and evolutionary behavior within the context of the Planet Nine Hypothesis, and find that BP519 adds to the circumstantial evidence for the existence of this proposed new member of the Solar System,” said authors of the paper.
The clues leading to Planet Nine are mounting up, but astronomers have yet to find direct evidence of its existence.