Something heavy seems to be causing Uranus and Neptune to move in a different orbit than what we can currently account for with the celestial objects we know of. Is there a 9th planet? Does planet 9 exist? Is planet X real? What might it look like? And how did it get so far out in space?
We have been looking for planet 9 for a long time but haven't found anything after decades of searching. Why haven’t we seen anything? There are a few reasons.
1) maybe there is no planet 9, and the reason for the orbital anomalies is due to a problem with our mathematical models.
2) Harvard astronomers suggest that it may be a primordial black hole the size of a grapefruit. This would have the approximate mass of Neptune.
3) And there are scientists who think that we have poor data or are misinterpreting the data, and that the idea of a 9th planet is silly.
But there are some compelling reasons why planet nine is thought to exist. It is not just that it would have an effect on Uranus and Neptune, but also on other distant celestial objects in our solar system.
These objects are known as Trans-Neptunian objects, or TNOs, meaning objects orbiting beyond Neptune. Observations suggests that these TNOs are also not orbiting as expected.
They all tend to cluster together in their approach to the sun and their orbits are similarly tilted.
In 2016, Caltech astronomers Mike Brown and Konstantin Batygin proposed that a large 9th planet, four to ten times more massive than the earth, orbiting 360-620 times farther away from the sun than earth, could explain the similar orbits of at many of these TNOs.
This 9th planet would be extremely far away. When an object is so far away, very few photons from the sun reach it, and even fewer photons are reflected back to earth for us to detect.
Now if this planet exists, the question is how did it get there?
Brown and Batygin proposed that it formed closer to the sun like the other large planets of our solar system, but was ejected into an eccentric orbit after a close encounter with Jupiter or Saturn close to the time of the formation of the solar system.
Supercomputer simulations seem to suggest that this is a realistic possibility.
Others have proposed that this planet was captured from another star during a close encounter with another solar system billions of years ago.
Some suggest that planet 9 was once a rogue planet wandering in the Milky Way galaxy and was captured by our Sun’s gravity.
Could it have formed organically at its current orbit? This could have happened if the protoplanetary disk that formed our solar system was more massive and more extensive that we realize. Planet 9 would be about 600 times fainter than Pluto.
Furthermore, planet 9 would take 10,000 to 20,000 years to make a full orbit around the sun.
00:00 | Why planet 9?
01:30 | How did we determine that Planet 9 may exist?
04:30 | Why haven't we seen Planet 9?
06:06 | Evidence for Planet 9
07:30 | How far away is Planet 9 on human scales?
08:33 | How did it get so far away?
09:47 | What would planet 9 look like?
12:39 | Is it hiding where we can't see it?
13:30 | Further Study: A Field guide to the planets