How does a 'sun' start to burn?

Question

What makes them initially start to give off heat/light?

Answer 1

Stars arise from the collapse of a cloud of gas, due to gravity.

As the material coalesces, it becomes more and more dense and hotter and hotter. Eventually, the density, pressure, and heat are all high enough to trigger nuclear fusion: hydrogen nuclei - protons - fuse ... and a star is born.

In case you don't know, stars like the sun do not 'burn' per se. The energy they give off as light and heat is released from nuclear fusion reactions. This is also the source of energy that makes a hydrogen bomb so powerful.

Answer 2

The Sun's heat and energy burns different surfaces in two ways.

1) Ultraviolet radiation. The Earth's surface, espicially on clear sky sunny days, gets bombarded incessantly by the Sun's invisible UV rays. This type of radiation can dry up the Earth's surface, affecting lawn, garden or forest growth.

UV rays also can burn human skin, causing not only a visibly uncomfortable "lobster red" skin tone to fair skinned caucasion people, but these excessive exposure to these rays can cause serious skin cancers in ALL unprotected people; cancers that can be disfiguring and / or lethal.

2) Captured UV rays, concentrated into a single, visible focused light beam by use of a mirror or magnifying glass can also generate heat that can burn surfaces and start fires. This simple first grade experiment is basically a very simple laser---as well as a cheat towards a Boy Scout camping merit badge (you're supposed to use sticks and stones for starting a fire).

Answer 3

When an object reaches a certain mass; that mass has a large gravitational field where the immense pressure causes immense heat and fuses elements together.

In the case of Stars, its Hydrogen fusing to become Helium. The fusion releases all sorts of emissions, including xray, visible, ultraviolet rays, and other forms of radiation. Not to mention quite alot of heat.

Eventually, all the fusionable material is used up, and the star collapses or explodes (and then collapses often). This is what gives us neutron stars, black holes, and (super)Novas.

The larger a star, the hotter it is, the more gravity is has; and the faster it fuses hydrogen into helium.

Answer 4

Pressure intense enough to break the strong bonds between protons and neutrons, releasing their energy in the form of heat and light.

Answer 5

The sun has never stopped giving heat/light so we would never really know the answer to that question, but I am sure you will get lots of guess's coming your way.

Answer 6

A mixture of friction, radiation and the distortion of space and time.

Answer 7

http://en.wikipedia.org/wiki/Stellar_evolution