On April 25, 1990, the Hubble Space Telescope was placed into orbit by the Space Shuttle Discovery (STS-31), marking a revolutionary new era in astronomy. It orbits at approximately 300 miles (483 km) above Earth, placing it above the atmosphere, traveling 17,000 miles per hour (27,000 kph) and completing an orbit approximately every 95 minutes. For comparison, the International Space Station is in orbit at around 250 miles (400 kilometers).
Before Hubble’s deployment, astronomers had to contend with distortions introduced by peering through Earth’s atmosphere (the reason why stars “twinkle"), and Hubble not only enabled clearer images of stars and nebulae, but also allowed us to look farther back into time. It has achieved a number of “firsts,” including:
• First confirmation that supermassive black holes exist.
• First images of a star’s surface other than our Sun.
