Today’s post is written by one of the early career members of the New Horizons Science Team. Alissa Earle is a graduate student in Planetary Science at the Massachusetts Institute of Technology. Her work focuses on the long-term seasonal variations that may be affecting what we see on Pluto’s surface.
Pluto’s diverse surface, typified by the smooth bright plains of Sputnik Planum being adjacent to the dark terrains of Cthulhu, defies any easy explanation for how it got that way. In my work, I am trying to explore how “seasons” on Pluto might be part of the explanation.
There are two reasons for Pluto having seasons. The first is for the same reason that Earth has seasons. The second is unique to objects with elongated orbits, like Pluto.
Both Earth and Pluto have seasons because their spin axes are “tipped over.” Earth has a rather modest tilt, only about a 23-degree slant compared with being straight up-and-down in its orbit. The consequence of this tilt is that over the course of one year, the North and South Poles take turns being tipped toward the sun. Earth’s North Pole is tipped more toward the sun in June, and six months later ...