Astronomers estimate that there are 200 to 400 billion stars in our galactic neighbourhood, the Milky Way. I guess that someone tried to count them in this fully-zoomable, ultra-high-definition 800,000-image mosaic and got tired around 296,351,284,702.
The 800,000-image mosaic was assembled by NASA last year from Spitzer Space Telescope photographs. But looking at a 37m image is hard unless you are in front of a printed copy. That's why someone has put them all together into a fully-zoomable panorama that you can enjoy here. [Thanks Joe!]