Planet X to be revealed within 5 to 10 years

Mar 18, 2008 09:37 GMT  ·  By
Artistic impression of Eris and the Sun in background. Eris is currently the farthest known dwarf planet slightly larger than Pluto
   Artistic impression of Eris and the Sun in background. Eris is currently the farthest known dwarf planet slightly larger than Pluto

There is definitely something out there, orbiting in the outer edge of the solar system. Maybe a planet with a size comparable to that of Earth, locked in a highly elliptical eccentric orbit, hidden away from our keen eyes. But what if we're looking in the wrong place? According to professor Tadashi Mukai from Kobe University, there are more than 1,100 currently classified objects beyond the orbit of Neptune, most of them having large orbital eccentricities and elliptical orbits that can only be explained by the gravitational influence of an Earth-sized object.

Alternatively, this object that we have regularly mentioned as Planet X could either be too far away for our telescope to observe or have a very unusual orbit that is difficult to predict. "We have reached our conclusions from simulations that explain the orbital elements. We are now looking in places that we have not looked before, and I think we will be able to see the planet within the next five of ten years," said Mukai.

What, Where?

The orbits of the eight known planets are relatively similar to that of Earth around the Sun, describing elliptical trajectories, almost all of them inside the same ecliptic plane, and enable accurate predictions of their paths through the solar system. Alternatively, the survey for the ninth planet were mostly conducted in the ecliptic plane of the solar system because almost all the mass is concentrated in that specific area, Mark Sykes from the Planetary Science Institute in Tucson believes.

However there is a problem, since the newly developed models of the solar system reveal that Planet X may have an eccentricity of 20 up to 40 degrees in relation to the ecliptic plane, similarly to the case of the dwarf planet Eris. Although Planet X could surpass the diameter of our planet - making it the larges rocky planet in the solar system - it could actually have a lower mass and density than Earth. It is approximated that Planet X may have a diameter between 10,000 to 16,000 kilometers, while Earth is only 12,800 kilometers in diameter.

Because it had formed so far away from the Sun, its iron content would be far smaller than that of Earth, thus its core may be composed of rock and the outer layers of a thick layer of ice water, methane or ammonia. Similarly to the dwarf planet Pluto, the surface temperature of the Planet X is approximated at between -253.1 and -243.1 degrees Celsius.

On the other hand, the Planet X could have formed in the inner regions of the solar system, being subsequently expelled to the outer regions through gravitational interactions, with a metallic core and a primordial atmosphere frozen on the surface. On its closest approach to the Sun, the orbit could measure a radius of only 80 astronomical units and, at the farthest distance, up to 200 astronomical units, meaning that it may take up to 1,000 years just to complete an orbit around the Sun, yet another reason why it couldn't have been spotted so far.

High eccentricity is the answer

Turning telescopes towards higher orbits could ultimately increase the chances of ever finding Planet X. "If this object is discovered, it would help us understand how many others there might be out there," said Sykes. If found, Planet X may spring another dispute in the astronomical community related to how it should be classified, as the definition of a planet today says that cosmic bodies that do not dominate their orbit cannot be classified as one.

However, they must find it first. The Pan-STARRS mission is expected to begin in 2009, and will be supported by multiple facilities around the world, amongst which the University of Hawaii, which will have the role of surveying the sky for asteroids. "I agree that there is the possibility of other large planetoids out there. We certainly cannot discount that possibility," said Sykes.