Topic ten

2. An apparent shift in the position of an object when viewed from different locations
6. the average distance between the earth and the sun
8. Horizontal distance between the crests or between the troughs of two adjacent waves
10. A contracting cloud of gas and dust with enough mass to form a star
11. A large cloud of dust and gas in space
15. 400-700 nm, the portion of the EM spectrum that is visible to the human eye
18. A device built to observe distant objects by making them appear closer
20. The star at the center of our solar system
22. the collection of eight planets and their moons in orbit around the sun, together with smaller bodies in the form of asteroids, meteoroids, and comets

1. The energy transferred through space by electromagnetic waves.
3. the brightness of a star as seen from Earth
4. a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
5. All of space and everything in it
7. the blue-white hot core of a star that is left behind after its outer layers have expanded and drifted out into space
9. the distance light travels in one year
12. how bright a star really is
13. the rapid expansion of matter from a state of extremely high density and temperature that according to some cosmological theories marked the origin of the universe.
14. a celestial body moving in an elliptical orbit around a star.
16. the brilliant explosion of a dying supergiant star
17. A chunk of rock or dust in space
19. balls of ice, rock, and dust in space with a tail
21. Electromagnetic radiation that can be seen with the unaided eye