Right now as far as we know, our Solar System has eight planets. However recent developments from NASA have indicated that there may be a hidden ‘Planet 9’ out there that hasn’t been discovered yet.
How can a planet be hiding out there right under our noses and what is it like?
Below, we look into all the facts about Planet Nine and review recent updates.
What is Planet 9?
Planet Nine is a large planet thought to exist in the outer reaches of our Solar System. We have never seen it, but there are indicators of it.
Whilst we do not know for certain that it exists, its presence would explain a number of other phenomena, such as the orbits of certain objects beyond Neptune at the edge of the Solar System.
If it exists, it could be massive – perhaps as big as ten times the size of Earth.
Why do people think Planet 9 exists?
Essentially, there are distant objects in a certain area of space at the edge of our Solar System whose direction of orbit would be best explained by the gravity of a massive planet affecting them.
In an October 2017 NASA release, the astrophysicist Konstantin Batygin outlined five indicators that suggest that the planet is out there and waiting to be found. These are:
- Certain distant objects in the Kuiper belt have elliptical orbits pointing in the same direction and tilt about 30 degrees “downward” compared to the flat plane within which the planets orbit the sun. This indicates a massive unseen force.
- A large minor planet in the outer reaches of the Solar System called Sedna was discovered in 2003. It had a peculiar orbit that led to the conclusion that something beyond the known eight planets had pulled it away from the Kuiper belt.
- The presence of a number of minor planets (Centaurs) with perpendicular orbits which could be explained by a massive unknown planet.
- Planet Nine could explain why the plane in which the eight planets of our Solar System orbit is tilted about 6 degrees compared to the sun’s equator.
- Some objects from the Kuiper Belt orbit in the opposite direction from everything else in the solar system and Planet Nine’s influence would explain this.
Taken together, this evidence is so strong that NASA’s Konstantin Batygin says:
“If you were to remove this explanation and imagine Planet Nine does not exist, then you generate more problems than you solve. All of a sudden, you have five different puzzles, and you must come up with five different theories to explain them.”
Where is Planet 9? What is its orbit?
Planet 9 is estimated to be a minimum of 200 times farther from the Sun than Earth – and a maximum of 1200 times. That means that it’s a minimum of 30 billion km away.
It lies far beyond the farthest confirmed planet in our Solar System – Neptune – which is approximately 30 times farther from the Sun than Earth (known as 30 Astronomical Units or AU).
The Kuiper Belt that is beyond Neptune is at 50 AU, which illustrates how far out Planet Nine is.
Watch this video from Caltech of the estimated orbit of the planet:
How big is Planet 9?
If the calculations are correct, Planet Nine would have about ten times the mass of Earth.
Is NASA looking for Planet 9?
No one has seen Planet 9 and so it has not been “discovered”. All evidence comes from the calculations of astrophysicists.
In the past couple of years, NASA astronomers at the California Institute of Technology Jet Propulsion Laboratory have started using the world’s most powerful telescopes to search for Planet Nine in its predicted orbit.
Why have we never found Planet Nine?
Because it is so far away and we don’t know exactly where it is. A planet that far away from the sun will be very faint and hard to detect.
What is “Planet X”? And what is “Nibiru”? Are these the same as Planet 9?
Some people (including NASA) have used the terms “Planet 9” and “Planet X” interchangeably in the past. However now most use the name Planet Nine.
This is because “Planet X” is the name referred to by believers of the Nibiru cataclysm – a doomsday scenario predicted by fantasists.
The evidence of the real hunt for Planet 9 then fed this apocalypse theory and the two have become mixed. It is therefore now preferred to stick with the name “Planet 9”, and leave a clear distinction between the science of finding this (probably real) planet, and fictional theories.
Planet 9 facts
- The idea of Planet 9 was first put forward in 1880 by the Scottish astronomer George Forbes
- Planet 9 may be tilting the whole Solar System to one side
- Planet 9 could be ten times the size of Earth
- If Planet 9 is confirmed to be real, it will be renamed and probably given a name connected to Greek or Roman mythology like the other planets of the Solar System
- Planet 9 is likely to be a minimum of 30 billion km from the Sun
Further information about Planet Nine
- NASA Planet X / Planet 9 information
- Wikipedia: Planet Nine
- Caltech Jet Propulsion Laboratory (NASA) on Planet 9
- Michael E. Brown & Konstantin Batygin paper from June 2016 that outlined the first indicators of Planet 9’s existence
- This NASA video: