Earths life depends on the suns heat and also on the suns ultraviolet sun rays. without the suns heat, basically everything on earth would get extremely cold. photosynthesis would die and also humans would die.
The angle of the sun is very important to humans and every living organism. Every living organism on earth would be killed if we did not have heat. The universe outside of earth is about -287 degrees Celcius. If there was no more heat, then we would be the same temperature as space is today. Humans would be able to live for a couple of months without heat but after there is no more heat source, then we, and everything on earth would be done for.