According to Khan Academy, Meteorite badges are common and easy to earn when just getting started.
Meteorite Badges on Khan[]
Meteorite Badges igenerally are the easiest to attain. The "Makes Perfect" badge, which comes from practicing one math skill, may well be the first badge many users earn. Another possible first badge is "Nice Listener," which a user earns after watching 15 minutes of video on one topic. For many topics, if a user watches all of the videos, they will surely earn this badge. Also "Apprentice Programmer". A retired Meteorite Badge that was once almost every user's first was the "Math Pretest" badge.
On the flip side, it can be debated as to which Meteorite Badge is the hardest to obtain. Some would say the "Brain Builder" badge, since the test it results from was glitching for a while, so that users couldn't access it. "Persistence" is another Meteorite Badge that some users find difficult to earn.