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A Galaxy is a massive, Gravitationally bound system that consists of stars, stellar objects such as brown dwarfs and nutrion stars, nebulae, an interstellar medium of gas and dust, black holes, and a unknown component of dark matter. examples of galaxies range from dwarfs with as few as ten million stars to giants with a hundred trillion stars or morw, each orbiting through thier galaxy. there are probably more 170 billion galaxies in the observable universe.
. pinwheel galaxy facts?
the pinwheel galaxy in the constellation ursa major the greater bear is a great design spiral, meaning that it has well defined spiral arms and dust lanes that extend all around the body of the galaxy. It was descoversd in 1781 by astronomer pierre mechain, and included as object number 101 in charles messier's list of celestial objects.
