Thus quoth Benji as he explained the theory of why astronomers think there’s another planet out way past Pluto. Here’s what transpired.

I sat down to write a new daily board, which says the date and Benji’s agenda for the day. Before I started, Benji said, “Wait! I want to sure you something.”

A little background. Benji really wants to be an astronomer when he grows up, and whether he does or not, it’s a fun hobby for a kid with lots of interesting exercises and experiments. There are also tons of videos on space stuff, naturally. Benji’s especially interested in the hypothetical Planet 9, which is somewhere way out in the Kuiper Belt, or maybe father. Who knows.

A few days ago, Ian and Benji watched some videos explaining some concepts about Planet 9, why astronomers think it’s out there, what they hypothesize about its physical properties, etc. I got a little summary of the videos then, and figured that was the end of it.

I was so wrong.

This morning, Professor Benji took up the chalk to draw a diagram that explains why the orbits of trans-Neptunian objects like Pluto, Eris, Makemake, and Haumea strongly suggest the presence of another, more massive object that we haven’t yet found.

He then went on to speculate about the material composition of the planet;

Elucidate on its mass relative to other Solar System objects (Earth and Neptune);

And theorize about the existence of many other such objects yet to be discovered. 

Granted, much of this latter material contained elements of speculation, but it was speculation informed by 2.5 years of education about planets and their properties.