Theory 1 -- star creation

Plasma merges together to create a star molecule. The more plasma, the larger the molecule. They can grow to extreme sizes because of this.

Theory 2 -- possibility of time travel

Have you ever heard of a gravity well? So they are so strong they can bend space, and since space and time are closely linked, they can bend time.

Theory 3 -- white holes

Black holes are NOT gates to other universes. So they dont lead to white holes. So gravity wells absorb space bodies and create holes in time called white holes and launch the celestial body out of the white hole.