"But even though it's there, dark matter watches the galactic dance from the sidelines. While the stars and gas clouds all move gracefully round each other on the dance floor, dark matter just hangs out, looking sulky."<br/><br/>Source: <a href='http://arstechnica.com/science/2016/02/spotting-dark-matter-by-the-way-it-moves' target='_blank' rel='nofollow'>http://arstechnica.com/science/2016/02/spotting-dark-matter-by-the-way-it-moves</a>/