When I was a kid, there were 9 planets. We really didn't know if other stars had planets circling them or not. Today, we now know of hundreds of these exoplanets, detected using various means. But it wasn't until 2008 that we finally clutched the Holy Grail: a bona fide, 100% confirmed direct image of one of these planets.
The image above is from the Hubble Space Telescope. It was observing the bright star Fomalhaut, which you actually can't see in the image because its light was blocked purposely so that fainter material around it could be seen (just like when you look for an airplane near the Sun and block the sunlight with your hand). The ring is a vast torus of dust leftover from the formation of the system, and we knew from its shape there might be a planet near it. And sure enough, an image from 2006 was compared to one taken in 2004, and a moving dot was found: the planet Fomalhaut b. It orbits the star at a distance of 16 billion km (10 billion miles), much farther out than Neptune is from the Sun. That's why we could see it at all; had it been much closer it would be lost in the glare of the star, a billion times brighter.
I love this picture (as well as another released at the same time of more planets orbiting a different star): it is solid evidence that we are learning more about our Universe everyday, and that questions we have had for centuries, for millennia, are answerable if we put our considerably clever minds to them.
Related posts: Huge exoplanet new items: pictures!
Credit: NASA, ESA, P. Kalas, J. Graham, E. Chiang, E. Kite (University of California, Berkeley), M. Clampin (NASA Goddard Space Flight Center), M. Fitzgerald (Lawrence Livermore National Laboratory), and K. Stapelfeldt and J. Krist (NASA Jet Propulsion Laboratory)