“Answers” is a word that hints that you are still thinking of it as human-like consciousness.

A valid point could be that our consciousness is social (“answering” is a thing), and by extension any alien consciousness we expect would also have to be social as one of the constraints that make it sufficiently human-like.

That is a good point. I need to clarify my consciousness about it.

In general I don't think a consciousness needs to be social to react to other consciousness. They might pose a threat or benefit. Say we want to build a dyson sphere and that would disrupt the suns ability to communicate with other suns (also social I know). I try to find better examples ..

Is there any other definition of consciousness than one of a subjective experience that observes and reacts to its environment?

What is a subjective experience? To me, this seems like an infinite regress problem.

Subjective experience is the awareness of an internal representation.

What is awareness then? Do you see my point? Either you end up with a circle of references or an infinite regress of definitions to describe the ineffable.

It’s the problem of qualia [1]. They can’t really be defined, only pointed at. My experience of seeing the colour red is non-universalizable. Thus the word red can only point at it, it can’t describe or define it.

[1] https://en.wikipedia.org/wiki/Qualia

I would say there is no working definition of consciousness at all—and potentially there can’t be a complete and provably correct one, if we assume Gödel’s incompleteness theorem is true. The reason is that our arguments about consciousness originate from consciousness itself, we are building a model of the system while being inside of it. The only definitive statement that can be made, I guess, is that consciousness exists.

As far as consciousness that doesn’t react, there are materialist/behaviourist/illusionist views that hold that only observed behaviour matters and anything else may well not exist, but I personally am not convinced by them.

Even that wouldn't indicate the sun is conscious. Your computer responds when you press a key, is that proof it's conscious?

(I don't think it's impossible that computers are conscious, but I cannot even proof that humans other than me possess a consciousness)