Sounds like you had a strong random, as I call them, come through. The dog would have been able to see it and probably tried to protect the children and got a smack. That spirit meant no harm it sounds like it was very strong and could have caused issues if it wanted, and didn’t it left, so it’s benign.
Do you have wards on your house? Wards are like magickal fences that say “keep out” to random spirits so that doesn’t happen.
Otherwise ghosts and astral beings tend are all over the place and they don’t respect boundaries like walls at all. They get curious and scare people who aren’t expecting them.
I would cleanse via smudging for good measure but it’s sounds like it was a flyby.
As a mage you attract interest on the astral, you are doing interesting things most humans don’t do and they come to look. If you are not using techniques like wards and shields to set boundaries you can expect more of this, very randomly. Keeping you and your loved ones and your space clean of random spirits wandering about is part of maintaining what’s called “spiritual hygiene”. As a mage it’s also important to do this to limit parasites and impostors during workings. Check out the thread we have collecting a few member’s tutorials and advice on this: