Huge invisible object flew our home. Had a shadow on ground

I was looking out my kitchen window when I heard which I thought was an army helicopter. The sound was low and heavy. I stared at the sky waiting for it to come past, when it didn’t I assumed it went in another direction. As I’m starting to look away that’s when I noticed a huge dark shadow go across the parking lot while I’m still staring at the sky. The sky was clear. There was no clouds, it was bright sky. Meaning this object was invisible but had a shadow. Later that night, I let my dog out to potty. I leave the backdoor open while I’m letting the dog out . When my dog was finished, we went in the house. As I’m going up the stairs I notice a figure going up the stairs, taking the last step and turning where the open living room is. It wasn’t an adult size, more so of kid height. It was transparent but lightly cloudy white like (Casper the ghost) with a blue outline. If I would’ve blink I would’ve missed it. This happen around 8pm