Twenty one years ago today, the space shuttle Discovery lifted off into space to deliver the brand new Hubble Space Telescope into orbit around Earth.  Hubble revolutionised the art of observational astronomy by delivering some of the most astonishingly detailed, clear, and frankly beautiful space images ever seen.  The HST had a difficult youth and was a disappointment to its parents when it turned out to have vision problems — its primary mirror suffered from a spherical aberration which made it impossible to focus clearly.  Fortunately, this problem was solved when astronauts in the first servicing mission installed an optical package which corrected the errors in the mirror:  It was fitted with spectacles!
In the years since, the HST has enjoyed a number of extra servicing missions which both performed routine maintenance and upgraded the telescope’s performance and capabilities.  The HST continues to do excellent science, provide unmatched views of the universe, and return breathtakingly gorgeous images.  The picture to the left, of a pair of interacting spiral galaxies, was released today as a special commemorative image for HST’s 21st birthday.  Many happy returns, Hubble, and may you last many years more!