Answer:
A leathery snake, with a stinging bite. I'll stay coiled up, unless I must fight.
What an fill a room but takes up no space?
I turn around once. What is out will not get in. I turn around again. What is in will not get out.
What zips through the sky with a tail of fire and dust. It could be an omen, its origin to discuss?
What can go through glass without breaking it?
I appear in the morning. But am always there. You can never see me. Though I am everywhere. By night I am gone, though I sometimes never was. Nothing can defeat me. But I am easily gone.