Thousands of years ago the sky gazers of the classical world knew about six planets:
Mercury, Venus, Earth, Mars, Jupiter, and Saturn.
Thanks to the invention of the telescope, Uranus was discovered in 1781.
But discrepancies in its orbit meant that something was tugging at it.
Sure enough that something turned out to be Neptune.
Ever since scientists have wondered if there might be yet another planet in our solar system
sometimes called Planet X.
Now astronomers have strong evidence for one.
A planet roughly the size of Neptune
with a mass ten times the Earth's and a thick atmosphere of
hydrogen and helium.
Just as Neptune was predicted based on its influence on Uranus,
the evidence for Planet X is indirect. Astronomers observed six small
solar system objects and noticed they come closest to the Sun in a unique
configuration. There's only a one in fifteen thousand chance that this
orbital clustering is a coincidence. It is much more likely that Planet X has
shepherded the six objects into their orbits. This explodes our conception of
the solar system because Planet X would loop around the Sun unimaginably far
away, in a strange elliptical orbit so far away that it takes fifteen thousand
years to make the trip. By comparison Neptune's orbital period is 165 years.
Of course, not everyone will be convinced of Planet X until we have visual proof.
Researchers are now using one of the world's largest telescopes, Subaru in
Hawaii and they say they have a reasonable chance of finding Planet X in
the next five years
Once spotted, we can welcome Planet X as the ninth planet in our solar system.