Asteroids change position in our starry sky as they orbit the Sun. Since they are part of our own Solar System, they are closer to us than the background stars. Our Earth also orbits the Sun and rotates on its axis. All these motions combine to shift the positions of the asteroids in these images. The stars in these images look bright and small.
Stars look bright because emit light from the nuclear fusion happening in their cores.
These stars are really huge but they look small because they are very very far away. Asteroid Images .