How does jupiter get it's gravity, being without any solid mass?

Any astronomy whizzes out there? I also wondered how Saturns ring stays in the perfect circle, rotating around the planet as it does? What holds it there and how has it stayed like a hula hoop for so long?

Paula

Well to your first question. Saturn is considered an outer planet. While most of the planets mass is composed of ice and gases. Saturn does have a inner core not unlike that of Planet earth. It's gravity is orbit is maintained by this core.

Saturn's rings are made up of millions of pieces of rock and dust. The gravity of Saturn holds it all in place but there are some moons that go around Saturn (just like our Moon), called shepherd moons that help to keep the rings in place.

Jupiter gets it mass because all that gas still weighs a lot. hundreds of earths would fit inside jupiter. its just huge. plus the gravity deeper in could of caused some of the gas to condense into liquid. so its heavy because its so huge. also saturns rings should of floated away or come in to the planet by now, but no one knows why they havent.