Have you noticed that when you look into a wormhole, you see an image of that part of the universe where you will end up if you enter the wormhole? Looking at this wormhole, one might recognize several nebula typical of the sky of perhaps the Insmother region.
To understand how the image visible in the wormhole is formed, let us begin with depicting the curved space near a traversable wormhole connecting two "flat" spacetimes. We will stick to two spatial dimensions, and pretend that we are ants that can only move on the sheet. That allows to embed the sheet in a third dimension just to make visualization possible - but keep in mind that for the ant this third dimension does not exist. The wormhole then looks like this:
It is a curved surface, with a neck connecting two sheets. The upper sheet could be flat spacetime somewhere in Domain, the lower sheet could be flat spacetime somewhere in Seclusion. The wormhole connects both through a narrow neck. The ants (and Amarr exploration frigates) can travel from one sheet to the other via a continuous path.
Now let's imagine you are at a certain distance from the wormhole and you shine a powerful laser beam, such as the ones commonly found on our ships. Start by pointing the laser in a different direction than the wormhole. The laser will highlight a straight line away from you. Now, as you point it closer to the edge of the wormhole, the line will bend, and your pointer will be deflected.
The left image shows the curved spacetime with a wormhole. Note how the rays, emitted by someone in the "lower" universe, remain in the lower part. From the point of view of the observer, the rays look as in the right image, where the circle represents the wormhole opening. You can clearly see the deflection when pointing near the wormhole's edge. It is in fact much stronger than the deflection from a star or any other commonly found massive objects, except of course black holes. Very close to the edge, the rays can even loop around. That is why you see an mirror image of space around you very close to the wormhole's edge. This is gravitational lensing in action.
Next, point the laser into the wormhole. Now the laser beams follow paths like these:
They cross from the lower universe (for example somewhere in Seclusion) to the upper universe (for example Domain). In the laser pointer's own universe, the rays are seen to enter the wormhole, as shown by dashed lines in the right figure. They emerge in the universe on the other side (full lines flaring out). When pointing closer to the edge, you can see that the rays swirl around while they are in the neck of the wormhole, and are strongly bent.
Tracing the light backwards, this means that you will get the full 360 degree view of the universe on the other side, visible as an image in the wormhole. Closer to the edge of the wormhole, the image gets more compressed and scrambled and harder to distinguish. The view is less distorted in the center, but note also that the rays (black and red) towards the center of the hole bend back - so you see a mirrored image of the target universe.
((ooc note: I made the figures in Wolfram Mathematica; they show the geodesics of the classic textbook metric for traversable wormholes first proposed by Morris and Thorne in Am. J. Phys. 56, 395-412 back in 1988 and used in science fiction ever since))
