I'm trying to find out the name of some stories I read as a kid. I remember a little alien that would visit a child at night. I remember the alien going along in the air. I think he wore a clear bubble helmet. I read them in the 70s. I liked them because it was an adventure at night when everyone else was asleep. If I remember correctly the child found the alien to be a bit of a pest.
Could it be Spaceship under the Apple Tree by Louis Slobdodkin? I read this book series as a 6 year old in the early 60's. It was my first introduction to science fiction although it probably would be more accurate to categorize them as fantasy now.