Gravity.: Gravity is the force that acts at a right angle to the path of an orbiting object.
Gravity
The moon doesn't smash into the earth because the gravity from the earth keeps the moon in orbit around it.
The correct answer is Solar systems
Astronomy deals with studying the cosmos and everything that encompasses it such as stars, planets, meteors, asteroid, satellites, and similar.
Initial velocity v1 = 1 m/s
Final velocity v2 = 8 m/s
Mass m = 1000 kg
Change in momentum = final momentum - initial momentum
= m*v2 - m*v1
= m *( v2-v1)
= 1000 * (8 - 1)
= 7000 kg m/s