NASA And The Exploration Of Planet X
Planet X has been fabled in the astronomical circles for a long long time. Ever since Neptune was discovered back in the 1840's, it has scientifically been speculated that there is another huge planet like body lurking in our Solar System. This was due to the fact that Neptune's orbit seemed quite a bit 'off' than expected and it could only be attributed to the fact that there was another gaseous body that lied ahead yet near enough to it to cause the disruption through its gravitational pull. Neptune itself was discovered because astronomers found oddities in the orbits of the Uranus, Jupiter and Saturn, which many believed had to be caused by a planet still father from earth and the Sun.
That led to many exploratory missions in the following decades and it wasn't until 1930 when a tiny planet like body was discovered and it was named Pluto. Although Pluto was not identified as the Planet X since it wasn't large enough to explain the orbital patterns of all four planets; thus science looked for something beyond Pluto, possibly a gas giant as large as Jupiter.
Ever since, there have been regular missions to discover this hidden planet. It has been even linked to a few 'doomsday' collision theories as well in the past, including the big 2012 scare.
Does Planet X exist?
All evidence collected till today points to the contrary. Serious attempts to locate this body have been failing ever since early 20th century. The probes that have been sent into space haven't moved in a way that would suggest the strong gravitational pull of a Planet X.
Another contributor to the demise of the Planet X theory is that the space probe Voyager 2 gave more accurate measurements of Neptune, which explained away mathematical irregularities in its orbit. Hence the original irregularities that led to the speculation of existence of another big planet were proven incorrect and re-evaluated.
Yet this didn't entirely rule out its existence since there was still unexplained phenomenon in space that couldn't be attributed to the existing placements. Due to this, the very concept of Planet X was re-defined to say that it is a brown dwarf star than a planet. A brown dwarf is a body on the edge of being a very large planet or a very small star.
None of these theories are though confirmed and all carry the same weight.
NASA's exploratory mission-
NASA recently carried out a very elaborate mission to discover hundreds of millions of celestial bodies and did not find any such evidence of Planet X. It was called the NASA's Wide-Field Infrared Survey Explorer (WISE)and operated from 2010 to early 2011.
As confirmed by NASA, this recent study which involved an examination of WISE data covering the entire sky in infrared light, found no object the size of Saturn or larger exists out to a distance of 10,000 astronomical units (au), and no object larger than Jupiter exists out to 26,000 au. One astronomical unit equals 93 million miles. Earth is 1 au, and Pluto about 40 au, from the sun.
This mission performed two full scans of the sky - with essentially a six month gap between scans. The survey captured images of nearly 750 million asteroids, stars and galaxies. In November 2013, NASA released data from the AllWISE program, which now enables astronomers to compare the two full-sky surveys to look for moving objects. This is because the more an object in the WISE images appears to move over time, the closer it is.
"The outer solar system probably does not contain a large gas giant planet, or a small, companion star," said Kevin Luhman of the Center for Exoplanets and Habitable Worlds at Penn State University, University Park, Pa.
Although what it does contain are several thousand new residents in our Sun's backyard, consisting of stars and cool bodies called brown dwarfs. The second WISE study, which concentrated on objects beyond the Solar System, found 3,525 stars and brown dwarfs within 500 light-years of the Sun.
Despite the large number of new solar neighbours found by WISE, "Planet X" did not show up.
So what does this mean?
So the conclusion for now remains that there isn't a Planet X that was originally speculated in the late 19th century. There may be another body that may explain the irregularities in orbits, however a planet as large as Jupiter or Saturn is ruled out. Also, considering the fact that technologies have advanced manifold since the beginning of the last century it lends even more credibility to the current conclusions.
Also, simple and common facts that any large object moving towards the inner Solar System would be one of the brightest objects in the night sky and it would mess up the orbits of the other planets and asteroids that astronomers carefully observe every make it easy to negate the Planet X theory.
Previous speculations about this hypothesized body arose in part from geological studies that suggested a regular timing associated with mass extinction on Earth. The idea was that a large planet or small star hidden in the farthest reaches of our solar system might periodically sweep through bands of outer comets, sending them flying toward our planet. However, the Planet X-based mass extinction theories were largely ruled out even prior to the new WISE study.
More than in actual scientific data, this planet seems to exist in pop culture and unexplained doomsday theories that give it more traction than necessary.