When you look at stars through the air, their light gets bent and scattered. That is why stars seem to twinkle. This twinkling looks pretty, but it actually blurs the image. Ground-based telescopes have the same problem. Even the best telescopes on mountaintops cannot fully escape the atmosphere's interference. Scientists solved this problem by putting a telescope in space. On May 20, 1990, the Hubble Space Telescope sent its first photograph from orbit. The image showed a cluster of stars called NGC 3532. Above the atmosphere, there is no air to blur or scatter the light. Hubble can see objects that are billions of light-years away with remarkable clarity. But the beginning was not smooth. After Hubble's launch, engineers discovered that its main mirror had a tiny flaw. The images were blurry -- not because of the atmosphere, but because the mirror was slightly the wrong shape. In 1993, astronauts flew up to Hubble on the Space Shuttle and installed corrective lenses, much like a person getting glasses. The fix worked perfectly. Since then, Hubble has taken some of the most stunning images in the history of science, including photos of galaxies colliding, stars being born inside colorful clouds of gas, and the deepest views of the universe ever captured.