TNB Night Owl – Planet Nine From Outer Space

Pluto July 13th, 2015. Photo by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

No, sorry, this Night Owl is not about the sci-fi movie, Plan Nine From Outer Space (1959). Maybe MrsMaryLou will treat us to a review of that classic B-movie one day. For now however, all you have is me and the Ninth Planet and its friends – mostly friends, in fact, with very little to actually say about the Ninth Planet.

Pluto fans will be disappointed to learn that it is not the ninth planet that we are referring to, as Pluto has been downgraded to a dwarf planet and is considered a trans-Neptunian object (TNO). Did you know that in addition to Pluto, there are thousands of known TNOs out beyond Neptune?

Our Solar System is much, much, much bigger than we were taught back in the day. The second TNO was discovered in 1992 (the first being Pluto in 1930). Since then, around 3,000 additional minor planets have been discovered ‘out there’. (Any asteroid or dwarf planet is considered a minor planet, ergo minor planets come in a wide variety of sizes).

‘Out there’, in this context, means out at the distance of Neptune and beyond. Neptune is 30.1 astronomical units (AU) or 4.5 billion kilometers (2.8 billion miles) from the Sun, where one AU is the distance between the Earth and the Sun. Pluto averages 40 AU from the Sun.

One organization that has most recently been successful making new TNO discoveries is the Dark Energy Survey (DES), an endeavor whose purpose is to “map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe”.

Scientists have announced that within the DES data, they were able to identify a total of 316 minor planets in the Trans-Neptunian region of the Solar System. Of this number, 139 minor planets had never been identified before. Those planets that had been previously identified acted as a control to confirm that the discovery technique was valid and reliable. Most of the new minor planets were found between 30 and 90 AU, but seven of the newly discovered TNOs are out beyond 150 AU. (Back of bourke! That’s a lot of AUs!)

What they did not find, but continue to look for, is the elusive Planet Nine. And why, you might ask, are they even looking for it? After the discovery of Neptune in 1846, astronomers began to believe there was another large and massive body even farther away from the Sun, that caused perturbations in the orbits of the giant planets Uranus and Neptune. That story is a lengthy tale, but let’s quickly cover some of the more trivial highlights. (Because it’s late and I have a publication deadline).

Astronomer Percival Lowell, a popularizer of planetary science in his day (circa 1886 – 1916) coined the term ‘Planet X’ to describe the giant planet thought to be out beyond Neptune. The ‘X’ in Planet X stood for ‘unknown’ and not for the Roman numeral 10 (as many of us junior science geeks were erroneously led to believe). Recall that in Lowell’s time, Pluto had not yet been discovered, so only eight planets were then known. After the discovery of Pluto (1930), and its errant designation as a real-planet-in-good-standing (just kidding, put the knives away) there were then nine known planets. Sometime after this people started confusing the ‘X’ as a Roman numeral ten but as you can now see, that’s not how it started.

When Pluto was discovered, there was some confusion as to whether it was the long sought Planet X, but it was not to be. Astronomers still believe that Planet X, or more accurately and popularly referred to (at least among astronomers) as Planet Nine, is out there. Current theories suggest it will be found in the vicinity of 200 AU.

As for the title of this under-baked and over-hyped Owl, “Planet Nine From Outer Space”, I’ve been searching for an excuse (any excuse at all, no matter how shameless or lame) to mention the science fiction movie in a Night Owl.

Found it.

Question of the night: Name your own question of the night, and provide your own answer. (I’m not your mother, clean up after yourself).

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About Richard Doud 65 Articles
No one is right all the time. No one is wrong all the time. No exceptions to these rules.