I was in Planetarium looong time ago, it's a good idea to bring 3 years old?

Yes...you can take a three year old. Normally whe. I visit there are young children around that age you can also check their website to see what type of planetarium show that they're going to have the last time when they talked about the planet they had Sesame Street as part of the presentation

The programs for younger attendees are on Saturdays at noon. Please check our schedule here http://fsc.fernbank.edu/planetarium.htm