 Here we are zooming into the pinwheel galaxy, M101. This is the largest and most detailed photo of a spiral galaxy that has ever been released from Hubble. The galaxy's portrait is actually composed of 51 individual Hubble exposures, in addition to elements from images from ground-based photos. The giant spiral disk of stars, dust and gas is 170,000 light years across, or nearly twice the diameter of our galaxy. M101 is estimated to contain at least one trillion stars. Approximately 100 billion of these stars could be, like our sun, in terms of temperature and lifetime.