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Back to nine planets?

María Isabel Montero

María Isabel Montero

AERTEC / Head of PMO & MRO – Madrid Division


Some years ago, the American astronomer, Michael Brown, dispelled our belief that we are living in a solar system made up of nine planets when he refused to classify Pluto as a planet because of its “small size”. Following a vote taken amongst the world’s most distinguished astronomers, Pluto was classified as a “dwarf planet“. However now, a decade later, he believes that there is a genuine ninth planet in our solar system.

We now have the telescopes and technology required to be able to see it, but we didn’t know where to look until now.

After much research and observation carried out together with his colleague Konstantin Batygin, they have recently published an article in The Astronomical Journal stating that we could be facing the discovery of a ninth planet in our solar system.

It would be located at a much greater distance than Pluto (about twenty times further out), with an elliptical orbit that would be at a distance of approximately 600 AU (astronomic units) at its closest point to the Sun, and 1200 AU at its most distant point (Pluto is at 40 au). It is estimated that it would take 10,000 to 20,000 years for it to make a complete orbit of the Sun, and it would be composed of a gigantic frozen mass, 5000 times bigger than Pluto itself.

There have already been several theories about the discovery of new planets presented to the scientific community, and they have almost always been based on the presence of massive objects that would influence the orbit of certain other objects in space. Most of these theories have later been refuted.

Despite the myriad of observations and mathematical calculations, nobody has actually seen the “ninth planet”, but we must remember the precedents of Neptune and Pluto, whose existence was predicted before they were seen for the first time. Although we now have the telescopes and technology required to be able to see it, according to Michael Brown “we didn’t know where to look” until now. Moreover, a planet that is so far away would reflect hardly any light from the Sun, which makes it very difficult to spot it – more so taking into account the fact that it seems to be located in an area of our galaxy where there is already a funnel of light.

For those who are curious or interested in finding out more about this research, the first results of the study are published in The Astronomical Journal. The research was initiated with the idea of refuting the hypothesis of another two scientists, Scott Sheppard and Chad Trujillo, who in 2014 pointed to the possibility of studying a part of the solar system until then unknown, where there could be massive objects that might fit within the current definition of planet. In view of his findings, Brown has had to confirm that we really could be facing a new discovery.

For now there is still a lot of research to be done and long hours of observation to be made before declaring the genuine discovery of this new planet, so for the moment it is entirely in our hands whether we believe that it truly exists or not.


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