Here is one of the best blog posts on putting Wolfram|Alpha into perspective:

Asking which result is “right” misses the point. Google is a search engine; it did exactly what it’s supposed to do. It isn’t making any any assumptions about what you’re looking for, and will give you everything the cat dragged in. If you’re an elementary school teacher or a flat-earther, you can find the result you want somewhere in the big, messy pile. If you want accurate data from a known and reliable source, and you want to use that data in other computations, you don’t want Google’s answer; you want Alpha’s. (BTW, the Earth’s circumference is .1024 of the distance to the Moon.)

When is this important? Imagine we were asking a more politically charged question, like the correlation between childhood vaccinations and autism, or the number of civilians killed in the six-day war. Google will (and should) give you a wide range of answers, from every part of the spectrum. It’s up to you to figure out whether the data actually came from. Alpha doesn’t yet have data about autism or six-day war casualties, and even when it does, no one should blindly assume that all data that’s “curated” is valid; but Wolfram does its homework, and when data like this is available, it will provide the source. Without knowing the source, you can’t even ask the question.