What keeps the objects in the solar system in orbit around the sun?

Answer 1

Gravity. The sun's mass keeps all the planets in place, following the same orbit.

It is the same with the moon around the Earth and for others planets moons.

If the moon was bigger than the Earth, then earth would orbit the moon because the moon's mass is bigger.

Answer 2

Actually, the stars in a galaxy don't move in a spiral pattern! Spiral arms are density waves, places where the stars and gas are a bit more densely packed together. They're a bit like traffic jams - individual cars move in an out of a traffic jam, but the traffic jam itself stays where it is. The same thing happens in a spiral galaxy - individual stars move in and out of the spiral arms, but the spiral arms move independently of them.

So what causes the spiral arms? It's a complicated effect caused partly by the gravity of everything in the galaxy pulling on everything else combined with its rotation - computer simulations show that that produces a kind of spiral pressure wave, like a gigantic sound wave, that compresses the stars, gas and dust and concentrates them into the spiral arms.

Because gas and dust are tightly packed together in spiral arms, they tend to form enormous clouds or nebulae where new stars form. The brightest stars tend to live for a very short time (millions of years as opposed to billions!) and don't have time to travel very far before they die. This is why the spiral arms are so bright - partly because they have a higher concentration of stars, but also because they're where all the bright stars live too. Between the spiral arms you get thinner gas and dust, fewer stars, and the stars are all dimmer and older because they've had time to move out of the spiral arms where they formed.

Our own Sun is currently in a small spiral density wave known as the Orion Spur. It seems to be a sort of mini-arm; a bridge linking two true arms of the Milky Way.

Answer 3

Gravity keeps objects in orbit. It there was no gravity then the object would fly away.

Answer 4

The gravitational force in both directions between the orbiting body and the central

body is the only force required. Which is lucky, because that's the only force there is.

Answer 5

The gravitational pull of the sun keeps objects in the solar system in orbit around it. The balance between the sun's gravity and the object's forward motion keeps it moving in a stable orbit.