What field of study allows a hobbyist to make a potential contribution What are some fields in which a professional  programmer (specializing in Data Science technologies) can pick up hobby projects that can actually contribute something to that particular field.  

I have heard rumors that astronomy is a field where hobbyists make serious contributions, is it true? What is the reason for this, i.e why astronomy of all fields has this special feature?
With programming you can make a contribution to virtually any industry. 

There's always a need for better, faster, smarter software that allows industry workers to get ahead of competitors and make the work day more efficient. 

There's also always a need for open domain software which, if created well, almost always gets a huge community such as GIMP. 

As a developer myself I can say that most worth while contributions will take more than just yourself and you may want to connect with other developers that want to help. 

Astronomy software can show constellations, star formations, and even have algorithms that predict where a planet or solar system may be and the probability that human or extraterrestrial life could be sustained on said planet.