Hunting for the real 'Planet X'

Discovery News ^ | Friday, 9 November 2012 | Mark Thompson

[BenLurkin]

Through accurate measurements of Charon's orbit, the mass of Pluto could be deduced. Ultimately it showed that the 'ninth planet' couldn't possibly have affected the orbits of Uranus and Neptune as observations appeared to show.

The renewed interest in Planet X was short lived as the Neptunian flyby by Voyager 2 in 1989 revealed its mass was less than thought. Reapplying this knowledge showed the outermost "ice giant" planets were behaving exactly as they should and the orbital perturbations were down to observational error. It seems the myth of Planet X had finally died.

This could have been the end of the Planet X saga, but recent studies of the Kuiper Belt - a region of icy minor planets located in the outermost reaches of the solar system - suggest this may not be the case.

The Kuiper cliff

It would be reasonable to expect the millions of frozen lumps of rock would gradually decrease with distance from the sun, but at a distance of 48 Astronomical Units (beyond the orbit of Pluto) they seem to drop off suddenly, at the so called "Kuiper Cliff."

Maybe Planet X is responsible for this strange unexpected feature in the outer edge of our solar system ... or maybe not.

The Voyager and Pioneer spacecraft heading out of our solar system haven't detected any substantial planets that might cause the 'cliff,' but space is vast; the chances of a spacecraft happening to fly past a previously undiscovered world would be highly unlikely.

Also, ground-based observatories and space telescopes (like NASA's Wide-Field Infrared Survey Explorer) have turned up little evidence.

But the jury is still out. Until an answer is found for the Kuiper Cliff, the ghost of Planet X will remain as a tantalising, but unlikely, explanation

[yawningotter]

There is no Planet X. Daffy and Marvin blew it up.

[Oztrich Boy]

"or, we could follow the letters"

[GreenLanternCorps]

GREAT IDEA!