Solar System may have two more planets

Our Solar System used to have 10 planets; then in 2006 Pluto was declared too small to be a planet, although many people still refer to it as one.

Soon we may add two more planets to our Solar System– two ‘extreme trans-Neptunian objects’ that may be hiding in the edge of our Solar System.

These two worlds have not yet been discovered, but scientists believe there are two Earth-like planets hiding beyond Neptune, the furthest planet from the Sun (if you don’t count Pluto).

How do scientists believe these worlds exist if they haven’t discovered them yet? The evidence comes from observations made of a belt of space rocks known as ‘extreme trans-Neptunian objects,’ also known as ETNOs.

When orbiting the Sun beyond Neptune, ETNOs should be distributed in a band about 150 Astronomical Units (AU) from the Sun. An AU is the span between the Earth and the Sun– about 150 million kilometres.

ETNOs should all more or less line up so that they are orbiting the Sun on the same horizontal axis as Earth’s planets, but about a dozen ETNOs aren’t following that rule.

If the observations of these ETNOs orbital planes to be believed, it suggests that they are being influenced by the gravity of another ‘invisible’ planet, which is known as the ‘Kozai mechanism,’ which means when a large body disturbs the orbit of a smaller object located much farther away.

“This excess of objects with unexpected orbital parameters makes us believe that … the most probably explanation is that other unknown planets exist beyond Neptune and Pluto,” said Spanish lead scientist Professor Carlos de la Fuente Marcos.

“The exact number is uncertain, given that the data that we have is limited, but our calculations suggest that there are at least two planets, and probably more, within the boundaries of our Solar System.”

For decades astronomers have been debating whether a hidden planet lies beyond Pluto. If this theory turns out to be true, Marcos’ results “may be truly revolutionary for astronomy.”