Will a Stolen Alien Planet Wipe Out Life on Earth?

In January, astronomers in California predicted the existence of a ninth planet in our solar system.

Since the announcement, scientists have been trying to discover more about the mysterious world, also known as ‘Planet X’

Theories range from how it might have been an exoplanet stolen by our sun to how it could have wiped out the dinosaurs.

Some have even suggested it may be on a collision course with Earth. 

Professor Andrew Coates, deputy director at the Mullard Space Science Laboratory, UCL, lays down exactly what we do know about this mysterious world and when we might discover it, in an article for The Conversation.

Ever since a study suggested that a ‘Planet Nine’ could be lurking in the outskirts of our solar system, astronomers have been busy trying to pin it down. 2010: The Year We Make... Best Price: $2.95 Buy New $5.99 (as of 10:40 UTC - Details)

As nobody has observed the planet yet, this research has been largely computational.

The existence of the planet was only suggested after scientists noticed that objects in its vicinity were moving strangely.

Since it was proposed in January, astronomers have modelled Planet Nine’s structure, orbit, estimated threat to Earth and possible origin.

But with all this data at hand, are we any closer to actually finding it? Let’s take a look at some recent results and what they really mean.

It may be an exoplanet 

The latest such study has come up with two different possible scenarios for Planet Nine’s origin.

One is that it may have started as a forming outer planet core from our own early solar system which was expelled to the edge of the solar system by some process, perhaps a collision.

However, another possibility is that our sun may have stolen Planet Nine from a nearby star in the Milky Way 4.5 billion years ago, which would make it our nearest extrasolar planet.  Stanley Kubrick Triple... Best Price: $5.57 Buy New $12.99 (as of 09:30 UTC - Details)

As star formation regions are relatively dense with stars – the sun was born in a cluster with perhaps 1,000 other stars – these can indeed interact.

While this is entirely possible, the research assumes that Neptune-sized objects were relatively common in this region – something we simply don’t know.

The study also suggest that further observations and modelling of the positions and orbits of minor objects in the solar system beyond Neptune now may provide further clues as to the origin of the proposed Planet Nine – whether this is core expulsion as originally proposed or exoplanet capture.

At the moment, the lack of direct observations of Planet Nine and the whole range of objects which may be affected by it mean that the explanations are poorly constrained.

In the meantime, this kind of work provides interesting ideas – but ultimately we need proof.

Excitingly, if it does exist and turns out to be a captured exoplanet, it is likely to be our best bet for visiting an exoplanet in the near future.

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