This is a long-term market to measure the base rate of it being proven and agreed on that at least one instance of a "UFOs = Aliens" theory was correct before the creation of this market.

It resolves to the one option representing the current time period when this happens, or "not by 2040" if this does not happen.

I plan for resolution to be based on Wikipedia, or whatever else is generally  agreed to be the most neutral and trusted online encyclopedia. I may require several trusted encyclopedias to agree, and am open to suggestions of which ones to trust.

If Manifold adds the ability to close options early, I will do so when a date passes without any consensus. I will not bet in this market, except to set the initial probability. 

This question uses a broad definition of "Aliens", any UFO using technology not of human origin would qualify.

For a version of this question with individual options so your mana doesn't get locked up, see here: