How earth and the sun move in space relative to each other

The two theories were:

1.Geocentric theory stating that earth is the centre of the universe and sun revolves around it.

2.Heliocentric theory stating that the earth revolves around the sun.

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation: