[syhprum (OP)]

At this distance with similar technology what could alien astronomers learn about our solar system

[Eternal Student]

Hi.

So basically you need to look at all the things we can identify about something 1000 ly away from us and then then you'll just assume the alien astronomers could do the same.

To start with, there's a good chance the alien astronmers could detect planets around stars that far away.   That's the good news.

Astronomers have discovered one of the most distant planets known, a gas giant about 13,000 light-years from Earth, called OGLE-2014-BLG-0124L      [Taken from a NASA website:  https://exoplanets.nasa.gov/resources/202/map-of-exoplanets-found-in-our-galaxy-artists-concept/       where there is more information if you want to read it]

    This depends on a lot of factors, for example if their viewing angle is such that our planets would transit across the sun or not.  So that would mean they are in the same plane as the plane of our solar system.   However, the article I linked to uses micro-lensing instead of just looking for driect transits, so there's some chance they could find the planets even if they were off that plane.    They need to be fortunate in other ways if micro-lensing is going to work  (e.g. there should be something obvious like a distant star behind some of our planets).    Also if there's a lot of dense gas between us and them then their view is extremely limited.    Overall, there's a lot of luck involved.... the alien astronomers need to have good viewing conditions and viewing angles of our solar system.

    The biggest problem is that there is a lot of sky and no obvious reason why the alien astronomers should be looking at our little patch.   When we look for interesting exo-planets which might support life we try and limit attention to planets that are in a "goldilock zone" around a star (where liquid water might be found etc.) - but that still leaves a lot of planets to consider:
    A 2013 study by Ravi Kumar Kopparapu .... (suggests that)....  there may be roughly 95–180 billion habitable planets in the Milky Way 

[taken from Wikipedia.  https://en.wikipedia.org/wiki/Circumstellar_habitable_zone]

     So, anyway, I think a lot of it comes down to viewing angle and all the matter (gas clouds in particular) that might ineterpose itself between us and them.   If the alien astronomers have a poor view of our solar system they might not identify much information about it at all and they would have very little reason to focus their attention on our patch of space anyway.  I mean, our sun doesn't seem to be especially interesting compared to most others.

     The other trivial fact which I think I can confidently report is that the alien astronomers can only see what our solar system was like 1000 years ago.   Although it was much the same then.

Best Wishes.

[Origin]

At this distance with similar technology what could alien astronomers learn about our solar system

They could tell what type of star sol is and they would be able to detect that there are some planets in orbit around sol.

Edit:  Oops, I didn't see that ES already answered.

[evan_au]

such that our planets would transit across the sun or not.

When the Kepler space telescope did a survey of exoplanets using the transit method, I saw a suggestion that this would pick up only 0.3% of such planets, due to the need to be directly in line with the plane of that planetary system.

As stars move across the sky due to "proper motion", so our stellar neighbors will move into this alignment - and then out of it. So we could predict the 0.3% of stars that could detect us via the transit method.

But stellar doppler shift allows us to detect planets that are quite far off alignment with their planetary disk.

[Eternal Student]

Hi.

But stellar doppler shift allows us to detect planets that are quite far off alignment with their planetary disk.

   Yes, good input that I had completely overlooked.
   I think you're talking about "wobble".   Stars move about the barycentre of the star + planet system, so the stars appear to wobble even if the planets don't quite transit across the face of the star.
   
Best Wishes.