Interesting... so they're making the calculations internally but not telling you how they got there then, right? So you really can't use wolfram alpha as a reliable source for anything?

Correct. It's conceivable that you could find a secondary source in their reading list that links to a primary source, but in practice going through their list of sources would be much slower than just doing the search yourself, meaning that site has zero utility in practice. (Assuming you care about the information you're getting being true, if you're writing a middle school paper about penguins then it probably gives you enough plausible deniability for having done the work, but for anything else there isn't much point.)

This link here lists exactly what their sources for AstronomicalData are: http://reference.wolfram.com/mathematica/note/AstronomicalDa...

But it doesn't tell you which source a specific fact comes from. You can't verify it or check if there are more recent sources with better values--relevant if you need good accuracy for a specific value.