For the Hubble telescope's "sweet 16" in 2006, NASA released the sharpest wide-angle view yet of M82, aka the Cigar galaxy.
Known as a starburst galaxy, M82 is a cosmic nursery in which stars are being created ten times faster than in our own Milky Way. Each of the starlike objects seen in the image is actually a cluster of up to a million stars. These clusters produce strong streams of charged particles, which compress the gases around them and begin the star creation process anew.
The idea of an orbiting telescope free from Earth's atmospheric distortions originated in the 1920s. Many decades later, Hubble has helped answer many longstanding questions about the numerous objects seen in the night sky.
Other discoveries were unexpected: Because of the time it takes light to travel, "very deep observations of the universe now reveal galaxies to us as they looked when the universe was only 600 million years old," said the Space Telescope Science Institute's Livio. "Today it's 13.75 billion years old. Nobody thought that we would see galaxies [of that age].
"Nobody anticipated that Hubble would discover the host galaxies of gamma ray bursts or the atmospheric composition of extrasolar planets," Livio added. "Yet Hubble did all these things and more."
The picture is among those that best highlight the Hubble telescope's scientific and societal impacts, according to astronomers on the 20th anniversary of Hubble.