M42 - The Great Orion Nebula
Telescope: 1200mm f/4.8 (aperture 254mm)
ISO6400 51 x 32s + ISO 800 35 x 16s (27.2 + 9.3 minutes)
This is a composite from two stacked sets of exposures. Otherwise the central part of the nebula would be burnt out before the outer parts could be fully seen.
By eye through the telescope only the central part is seen.
This is a region where a cloud of gas, mostly hydrogen, is slowly collapsing under its own gravity. Local parts of it collapse until the temperature and pressure become so great that nuclear reactions start and stars are born. The Hubble Space Telescope has photographed brown dots in the nebula which are nearly stars.
Our Sun will have formed in a similar way about 5 billion years ago. Like all stars it is converting hydrogen to helium and that produces a huge amount of energy, radiated out. The Sun has enough hydrogen to last for another 5 billion years.