Across
- 2. a star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass
- 5. the rapid expansion of matter
- 7. the curved path of an object round a star, planet or moon
- 9. the force that attracts a body towards objects with mass
Down
- 1. a celestial body moving in an elliptical orbit round a star
- 2. a fixed luminous point in the sky, remote incandescent body like the Sun
- 3. the natural satellite of Earth
- 4. a cloud of gas and dust in outer space
- 6. a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction
- 8. a hypothetical space object about the size of Mars that many astronomers believe once existed in the solar system, following an orbit similar to that of Earth and that collided with Earth