As you can see in the new group banner, there is an image of an unnamed planet, with a visible ring orbiting it.

It would seem that this is confirmation of other planets in the solar system that the planet (whatever you choose to call it) Equestria is on is a part of.

So is it a way of showing that Nightmare Moon encourages astrology? That at some point in the future, she may wish to explore other planets/moons in their solar system?

There is an observatory not too far from her castle, keep that in mind.

Maybe that planet is Equestria's saturn. I really like it. Also your idea sounds pretty cool.

4895913 It would be interesting if the Twilight of this timeline is a part of NMM's astrology department, it would fit her intellectual skills, so it would make sense.

4896088
That is true. However in my fanfic Twilight will learn that her counterpart died as a victim of a disease. Yeah, I wanted to avoid awkward meetings.

4896214 Seems rather anti-climatic to just let the Twilight of that timeline die like that, or be dead at all really.

4897405
Probably. But she is only dead in this story. Maybe in other versions of the verse she is alive.

4898223 Maybe, just seems like a wasted opportunity to me.

4898316
True. However in my fanfic the actual Twilight is stuck in the nightmareverse, so I have quite the opportunities.

Astronomy might be more popular in this timeline , and any comparatively close gas giants will look impressive.