Nothing excites people like a planet. In 2006, the International Astronomical Union (IAU) downgraded Pluto’s status to “dwarf planet,” and the internet jokes haven’t stopped since.
There’s this riff on an Eric Andre sketch:
— Smh Memes (@keep_kitty) April 1, 2019
Or this one with Pluto having a head-to-head with famed astrophysicist Neil deGrasse Tyson:
Unfortunately, Pluto is on track to get its heart broken again, as researchers are hot on the trail of a brand new planet. But first things first …
What is a planet?
The same infamous IAU defines a planet as having three distinct characteristics:
- It must orbit a star (in our case, the sun)
- The object must be big enough to have enough gravity to force it into a spherical shape.
- It must be big enough that its gravity cleared away any other objects of a similar size near its orbit around the Sun.
That last qualification is what got Pluto kicked out in 2006. As our understanding of the cosmos improves, our understanding of definitions changes.
What is Planet Nine?
A hypothetical planet, based on research done by Caltech astronomers Konstantin Batygin and Mike Brown. According to Space, the planet is likely to be closer and smaller than previously thought:
Observational evidence and computer-modeling work indicate that 10 Earth masses is an upper limit for Planet Nine, according to the new study. Indeed, 5 Earth masses, and an average orbital distance of 400 to 500 AU, are likely to be closer to the actual marks, the scientists found.
The most exciting news about the object is that it could be found even sooner than imagined. After outlining the planet in their study, the astronomers simply state that if it exists according to their research, it should be found within a decade.
If that happens, our solar system would once again be back to nine official planets. But no one should tell Pluto.
Image provided via Caltech/R. Hurt (IPAC)