Two things come immediately to mind for me.
The first is when we've worked really hard on an instrument, get it launched and first turn it on. When the data first start coming from the instrument and you realize it is working (mostly!) the way you designed, it is a big thrill (and very tense just before that point).
The second thing that I find exciting is when the pieces of a puzzle start to finally come together in a way that makes sense. When the data and the theory or models seem to work together, allow you to 'predict' what is expected for another observation and then you make the observation and it is as expected it is very exciting and satisfying. This means you are understanding at least the big parts of the physics that is at work.

Unfortunately, this doesn't happen as often as we'd like because generally we are studying very complex systems. We can't extract one small part or 'hold fixed' one part while changing the other parts to see what happens the way you can with some experiments in laboratories on Earth. Often there are a lot of things all happening at once and we're generally observing it from far away, so understanding it all it a huge challenge.

Hi Ariela!

I agree with Christina that working on an instrument for a satellite or rocket, seeing it get launched into space, and then being able to see the data from it is very exciting. It's also exciting when you worked on a paper very hard and it is finally published.

However, just looking at data can be very exciting too. Especially when you find something you haven't seen before. Last year, I was checking out some computer software with a co-worker while looking at data. The time period I was looking at had some really weird natural signals in it, although they weren't the type of signals I was studying. My co-worker had been helping me convert magnetic field data into sounds. He wondered what these weird looking signals would sound like, so he ran his program on the data. The signals sounded so weird that we were passing the headphones around to everyone and turning the volume way up to see their reactions. It was pretty funny! Even though most of us have heard a lot of "space sounds" before, we had never heard anything like this.