I Used to See Auras

I saw it for the first time when I was in high. I was doing my test in the class then looking around at the kids around me and when I saw my teacher, I saw a dark or dark grey color around his body from head to his shoes about 3 inches from his body. It followed him whenever he moved but in a slow way. I touched my eyes several times to make sure there was nothing wrong with my eyes and it still there until I left the class. Next day, I came to the class and saw my teacher and it was there but smaller and then faded out. I somehow tried to keep it there and it went back right there then I lost it after hours cause I needed to finish my test. For several years I thought it was spirit, I’m not sure why those days I could see his instead other people. I don’t remember when exactly I realized it’s actually aura but it was something.