Newly Discovered Deep Space Object Builds the Case for Planet 9

Dwarf Planet Eris
Impression Credit : ESO

One ongoing subject of fascination at InnerSpace is the cascade of discoveries of new objects at the extreme reaches of the solar system. Although all are incredibly distant, and may strike many as cold, dim, dirty balls of ice and rock, the fact that we still don’t know what all is out there is refreshing in a way. After all, it had to have been a bit of sad day in the Age of Sail when the last blank spaces on the map were finally filled in.

As long as we are still discovering new objects in our home solar system, particularly in the extreme reaches, we really aren’t trapped here yet, gazing out at the gulf between Earth and Proxima Centauri, consigned to waiting for Zefram Cochrane to show up and invent the warp drive, or someone else to start building generation ships.

One of the biggest mysteries waiting to be solved is the purported existence of an as yet undiscovered planet which may be the most logical explanation for a whole bunch of smaller objects behaving the way they do.

That planet is informally called Planet 9, and the smaller worlds behaving oddly are called trans-Neptunian-objects, minor planets which are not comets and exist beyond the orbit of Neptune. The largest and best known TNO is of course former major planet Pluto, but there are many others, and the count is growing.

As of this week, there is another designation to add to the list; L91, which is in an orbit so long it takes 20,000 years to go around the Sun. And like a number of other similar bodies, its orbital properties are suggestive of the presence of elusive Planet 9, says the duo of Cal Tech astronomers who deduced its existence earlier this year.

While the case for a massive planet the size of Neptune is building with each new discovery of a gravitationally disturbed TNO, perhaps it would be a good thing if the mystery lasted a little longer. Unless of course, there’s a Planet 10…