M33 (NGC 598) is a face-on spiral galaxy approximately 2.3 million light years away and with a diameter of 50,000 light years  (half the size of our Milky Way Galaxy). It is third largest galaxy a local group of galaxies which includes our Milky Way and Andromeda Galaxy. Given it proximity, it is possible to see the galaxy without a telescope on nights of extremely good viewing.  In that event, it is the most remote object that can be seen with the naked eye.

In the lower right of the picture is a very bright but apparently small “cloud” known as NGC 604 which contains more that 200 hot, bright stars within the cloud. NGC 604 is nearly 1300 light years across or 100 times larger than the Great Nebula of Orion (M42 which contains four stars in its center known as the "Trapezium"). Within our local group, only the Tarantula Nebula (best seen from the southern hemisphere) can match NGC 604 for size and number of stars. The stars in NGC 604 are approximately 30 million years old (young) and the largest stars are over 100 times bigger than our sun.