Planet Nine – Astronomy Now

The case for, and against, the still-unseen Planet 9

16 February 2021 Astronomy Now

New research questions the need for a “Planet 9” to explain clustered outer solar system orbits; proponents beg to differ.

Hubble spies double-star exoplanet in long orbit like hypothetical path of ‘Planet Nine’

14 December 2020 Astronomy Now

Hubble helps astronomers characterise exoplanet orbit that is similar to the path of a hypothesised “Planet Nine” in Earth’s solar system.

‘Planet Nine’ may not be needed to explain strange orbits

5 June 2018 Astronomy Now

Astronomers are searching for a presumed “Planet Nine” in the extreme outer solar system whose gravity could explain unusual orbits of several remote bodies. New research suggests Planet Nine may not be necessary.

Curious tilt of the Sun traced to undiscovered Planet Nine

20 October 2016 Astronomy Now

Planet Nine — the undiscovered planet at the edge of the solar system that was predicted by the work of Caltech’s Konstantin Batygin and Mike Brown in January 2016 — appears to be responsible for the unusual tilt of the Sun. The large and distant planet may be adding a wobble to the solar system, giving the appearance that the Sun is tilted slightly.

Extreme trans-Neptunian objects lead the way to Planet Nine

13 June 2016 Astronomy Now

In the race towards the discovery of Planet Nine, scientists from around the world strive to calculate its orbit using the tracks left by the small bodies that move well beyond Neptune. Now, astronomers from Spain and Cambridge University have confirmed that the orbits of the six extreme trans-Neptunian objects that served as a reference to announce the existence of Planet Nine are not as stable as originally thought.

Did the young Sun steal Planet 9 from another star?

31 May 2016 Astronomy Now

Through a computer-simulated study, astronomers at Lund University in Sweden show that it is highly likely the so-called Planet 9 is an exoplanet. This would make it the first such body to be discovered inside our own solar system — when or if it is found. The theory is that our Sun, in its youth some 4.5 billion years ago, stole Planet 9 from its original star.

Planet Nine: a world that shouldn’t exist

3 May 2016 Astronomy Now

Earlier this year scientists presented evidence for Planet Nine, a Neptune-mass planet in an elliptical orbit 10 times farther from our Sun than Pluto. New research examining theories how this planet could end up in such a distant orbit finds that most scenarios have low probabilities. Therefore, the presence of Planet Nine remains a bit of a mystery.

Compelling evidence for a ninth planet in the Solar System

20 January 2016 Keith Cooper

There’s strong new evidence that an undiscovered large planet exists on the fringes of our Solar System, according to two Caltech scientists who have looked at the odd behaviour of numerous distant Kuiper Belt Objects.