In winter we are looking in the opposite direction, towards the outer precincts of the Milky Way. The telescopic wonders here are of the our own spiral arm. By comparison Orion is the Sagittarius of the winter sky, while nearby Monoceros the Unicorn is the Scutum the shield of winter. About the latter two, in case you've never heard of them, they are devoid of bright stars but rich in star clusters and nebulae. Tomorrow, why do stars shine.
Stars require unimaginable, but quantifiable amounts of energy to shine as they do.
Using this equivalence of energy and matter physicists and astronomers found that the energy was the result of the fusion of hydrogen atoms to form helium atoms in the star's core. The reaction is stoked and controlled by the star's own gravity, trying to compress the star. The energy outflow keeps gravity at bay and keeps the star's size and brightness stable. This happy state of affairs ends when the helium byproduct builds to a critical mass, but that's another story. Tomorrow, the bright planets.