Astronomy

2. An oval that is centered on two points called foci; the shape of planets orbit
5. Weak radiation that is left over from the early hot stages of the big band expansion of the universe.
7. period when the sun is overhead at its furthest distance either north or south of the equator
9. Ratio of the distance between the foci to the length of the major axis
11. Used to calculate the rate at which the universe is expanding.
12. The state at which an orbiting body orbital and rotational periods are equal
15. Gigantic threadlike or sheetlike cluster of galaxies that is hundred of millions of light years in size.
16. The time of the year during which Earths axis is at a 90 degree angle to the sun

1. All types of electromagnetic radiation arranged according to wave length and frequency
3. Theory that proposes that the universe began as a single and has been expanding ever since
4. Process in which heavy atomic nuclei split into smaller, lighter atomic nuclei
6. Small, extremely dense remnant of a star whose gravity is so immense that not even light can escape its gravitational field
8. The study of the universe
10. The combining of light weight nuclei into heavier nuclei; occurs on the core of the sun where temperature's and pressure is really high.
13. Massive explosion that occurs when the outer layers of a star are blown off
14. Large cloud of interstellar gas and dust that collapses on itself, due to its own gravity.