Ahsoka Physics: Making a Hyperspace Jump to Another Galaxy

Rhett Allain
5 min readSep 8
Image: David (Deddy) Dayag/Wikimedia Commons (Available under CC-BY-SA-4.0). The Andromeda galaxy.

I’m just going to assume that you’ve already watched Ahsoka Part 4: Fallen Jedi. But here’s the important part you need to know (for the physics stuff). Baylan and Morgan are working to travel to another galaxy (and find Grand Admiral Thrawn). They have acquired the map and are making preparations for trip. Here’s the important part of their conversation:

Morgan: Once the guideline is established, we will be able to calculate the hyperspace coordinates.

Baylan: For the jump we’re attempting, if your calculations are off by even a little, we will be lost to the depths of the void.

So, let’s say you want to travel to another galaxy in a straight line (we can assume that both the start and finish locations are stationary). How precise would your calculations need to be so that you don’t end up in the “void of space”.

Since we don’t have the specifications of the either galaxy in the Star Wars universe, we can pretend like we are making a trip from our galaxy (the Milky Way) to the nearby Andromeda galaxy. This galaxy is 2.5 million light years from Earth and has a diameter 152,000 light years. Those are the numbers we are going to use. I’m going to also make the assumption that I just want to get to anywhere inside the galaxy and not to a specific star.

We can get an estimate for the amount of error in our planned path by looking at the angular size of the Andromeda galaxy as seen from our location.

If the galaxy is far enough away, we can assume that it’s diameter (d) is the same as the arc length a distance (r) away with angle (θ). This gives the following relationship.

This will give us the angular size (in radians) as long as both d and r are in the same units (which, they are — YAY!). Plugging in the values gives an angular size of 3.48 degrees. Yes, that’s kind of large — especially considering that the moon has an angular size of about…

Rhett Allain

Physics faculty, science blogger of all things geek. Technical Consultant for CBS MacGyver and MythBusters. WIRED blogger.