The Hubble Space Telescope’s new image of the Pinwheel Galaxy is worth lingering over — the thumbnail below can only suggest its power, so do click on it to see a larger JPEG, and click here to gain access to still larger versions — the fullsize original is 455 MB worth of data! The Pinwheel is spiral galaxy Messier 101; its image was assembled from 51 separate Hubble exposures along with elements from ground-based photographs. The final composite image in its glorious entirety works out to a colossal 16000 x 12000 pixels.

If you do download the full original, you’ll find all kinds of hitherto unseen objects. K.D. Kuntz at Johns Hopkins catalogued almost 3000 previously undetected star clusters in it. But to me this image is one of those perspective-makers that get us mindful, on days when we need it, of the scale of things cosmic. The Pinwheel is 170,000 light years across (that’s close to twice the size of the Milky Way), and it contains about a trillion stars. The extraordinary resolution of this shot reveals millions of individual stars and regions of star-forming nebulae.

So big is the Pinwheel that, although it’s 25 million light years away, it fills an area of the sky about one-fifth that of the full moon. Ponder how the universe keeps telling us that the most natural reaction to its immensities is simple awe. Ponder too that within the image we should be looking at about 100 billion stars that are Sun-like in terms of temperature and lifetime. Suddenly our 181 identified exoplanets seem a paltry list indeed!