What does Planet 9 look like? Astrophysicists now have an idea

8 Apr 2016

Storm over Earth image via NASA

A team of astrophysicists is trying to create an image of the still theoretical planet – Planet 9 – at the farthest reaches of the solar system, and it seems there’s a reason why we haven’t been able to find it.

Planet 9 remains controversial in astrophysics circles as, despite our seemingly good knowledge of the make-up of our solar system, there remains no physical sighting or proof of the existence of a ninth planet in our solar system beyond Pluto.

There have even been suggestions that this potential planet has played a significant part in the development of life on Earth, however, contributing to mass extinction events as, when its gravitational pull is at its weakest, enormous space debris is more likely to strike Earth, such as the impact that led to the extinction of the dinosaurs.

Breakthrough in January

A turning point in theories surrounding Planet 9 came in January of this year when a study was published in the Astronomical Journal by a team of researchers claiming there is scientific evidence to suggest the existence of a ninth planet.

The discovery was made after the researchers spent 13 years tracking the unusual orbits of two objects in the outer reaches of the solar system, known as the Edgeworth-Kuiper belt.

One of these objects, dubbed Sedna, was found to be different from other objects in the region by showing it was not affected by Neptune’s gravitational pull.

Now, a team of researchers from the University of Bern has taken these calculations and created what they believe to be an accurate description of what Planet 9 looks like, if it exists.

Planet 9 model

The Planet 9 model. Image via Esther Linder, Christoph Mordasini, Universität Bern

Planet 9 taking shape

Publishing their findings in the journal Astronomy & Astrophysics, the researchers said they believe that such a planet would have a radius equal to 3.7-times that of Earth with a temperature of minus 226ºC.

Using this planetary evolution model, the team has also revealed details that could explain why we have not been able to see it.

With its distance likely being 700-times further away as the distance between the Earth and the sun, it will have little reflective footprint, meaning it will be much more visible on the infrared spectrum.

Likewise, sky surveys undertaken on Earth in the past had only a small chance to detect an object with a mass of 20 Earth masses or less but a new generation of telescopes – like the Large Synoptic Survey Telescope under construction near Cerro Tololo in Chile – could have a chance of being able to spot it.

Speaking of the potential future sighting of Planet 9, lead researcher Prof Christoph Mordasini, said: “With our study candidate Planet 9 is now more than a simple point mass, it takes shape having physical properties.”

Colm Gorey was a senior journalist with Silicon Republic