universe

3. the force that attracts a body towards the centre of the earth, or towards any other physical body having mass.
4. the continuous flow of charged particles from the sun which permeates the solar system.
8. a cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter.
9. a celestial body moving in an elliptical orbit round a star.
10. a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
11. the rapid expansion of matter from a state of extremely high density and temperature which according to current cosmological theories marked the origin of the universe.
12. a hypothetical planet that, according to the giant impact hypothesis, collided with the Earth and created the Moon.

1. a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star.
2. a luminous spheroid of plasma held together by self-gravity
5. the curved path of a celestial object or spacecraft round a star, planet, or moon, especially a periodic elliptical revolution.
6. the natural satellite of the earth, visible (chiefly at night) by reflected light from the sun.
7. a star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass.