Astronomyis today in a golden age, one that began approximately in the early 1990s with the launch of theHubble Space Telescope. TheHSTand its counterparts, such as theSpitzer Space Telescope, have produced stunning images. Earth‐based astronomy at optical, IR, and submillimeter wavelengths has achieved comparable progress. The most striking advance has occurred in interferometry—especially optical interferometry, which produces spatial resolutions previously unimaginable in single‐aperture telescopes. The twin Keck telescopes on Hawaii's Mauna Kea, for example, are now referred to as the Keck Interferometer. Other Earth‐based instruments and techniques have likewise made enormous progress with, for example, the discovery of dozens of extrasolar planets.