#planetary collision

Fucking love this. -cc

To put it simply, no. Although Pluto’s orbit does cross into Neptune’s own orbital path, they have not, and will not ever happen to collide. Pluto has an orbital cycle that brings it closer to the sun, “inside” Neptune’s own orbit, every 228 years, and remains there for twenty years before returning to it’s original position. On the 21st of January in 1979 Pluto happened to “cross” Neptune’s orbit, thus temporarily repositioning itself and becoming the 8th planet from the Sun. Then, on the 11th of February in 1999, Pluto “crossed” back through Neptune’s orbit, and reclaimed it’s official place in our Solar System as the ninth planet, even though it’s now known as a dwarf-planet, and is expected to stay in this position over the next 228 years, until about the year 2227.

As you can see, even though the positions of the two planets themselves may change, and even perform a perceived dance with each other by crossing paths, they will never collide. Now I’m sure you’re wondering well why not? What are the actual “scientific” reasons that makes such a collision nearly impossible?

Well the reasons for this are just as simple as the initial answer. One of the things that indicate this collision will never naturally occur, save external forces pushing one planet into the other and vice versa, is due to Pluto’s orbit being tilted at an angle of 17-degrees, which, depending on it’s position in orbit, is above or below the plane of the ecliptic. You can view what this looks like in relation to the rest of the planetary bodies and their orbits in the image below, via Universe Today.

Another reason is for every three full orbits around our Sun committed by Neptune, Pluto makes two full orbits. The two planets are actually acknowledged to be in what is called a “resonance orbit”, specifically a 3:2 resonance orbit in this case, simply meaning Pluto’s orbital period is exactly 1.5 times longer than that of Neptune. Due to their respective orbits, they tend to never get too close, and to note, the closest they ever get to each other is about 2 billion kilometers. 

If Pluto did hypothetically collide with Neptune, it would most likely be a spectacular event. I’m not completely sure as to what would occur, play by play, if this collision were to happen, but I’m pretty sure Pluto would break up a bit before hitting Neptune and eventually be swallowed, creating a possible luminous reaction that could be bright enough for us to witness from Earth.

Although Neptune is quite a bit larger than Pluto, in the case of this collision, Pluto might take a chunk out of Neptune’s icy layers as it’s swallowed, along with potentially sending parts of itself out into space. This could be a catalyst for the formation of a new moon as the different projectiles get caught in an orbit around Neptune. The possibilities of how it would affect the rest of the solar system, as well as Neptune’s own moons, are numerous and depend on multiple variables such as the speed and angle of the collision.