Understanding Pluto's Neighbors

Later this month Chicago's Adler Planetarium will be premiering its new show Planet Nine. The program will discuss the New Horizons mission to Pluto, the dwarf planet's neighbors, and the search for Planet Nine (though I still argue Pluto should remain the ninth planet).

And in case you would like to read a little more on some of the other dwarf planets in the show (including the one that cost Pluto its place among planets), here is what the Adler Planetarium shared on its website:

Eris

The discovery of Eris prompted the International Astronomical Union to agree on an official definition of “planet” in 2006. Eris is almost exactly the same size as Pluto, yet it weighs 25 percent more. It is also remarkably bright, reflecting 97 percent of the light it receives from the Sun. To put that in perspective, the Moon reflects just 12 percent of the Sun’s rays.

Haumea

Shaped like a football, Haumea rotates incredibly fast—once every four hours! This object’s fast rotation causes its unusual shape. Were it rotating more slowly, gravity would pull it into a sphere, which is why it qualifies as a dwarf planet even though it isn’t round.

Sedna

Sedna’s orbit takes it deep into the far reaches of the Solar System, almost 20 times as far as Pluto ever goes. A year on Sedna is 11,400 times as long as a year on Earth! But perhaps the most interesting thing about Sedna is the hints it gives us that there are many more objects yet to be found at the edges of our cosmic backyard.

In the meantime, here is a video sharing more about the proposed Planet Nine from Astronomer Konstantin Batygi.