The Hubble Space Telescope opened its eyes 25 years ago this week, on May 20, 1990. The space-based observatory was placed into orbit on April 24, 1990, from the space shuttle Discovery, after which the space-based observatory underwent nearly a month of testing.
Hubble used its Wide Field/Planetary Camera to image several stars in its first attempt to photograph the universe. When new telescopes view the sky for the first time, astronomers refer to the event as "first light." This first exposure of a handful of stars, designed to focus the telescope, was taken over a period of 30 seconds. This image, showing first light for Hubble, was released along with the same field of stars as seen through the 100-inch telescope at Las Campanas in Chile.
"The region observed is centered on the 8.2-magnitude star HD96755 in the open cluster NGC 3532, in the southern constellation Carina. Identical small subsections of the HST and ground-based image pictures were chosen to highlight the difference in resolution," Hubble Space Telescope officials wrote in 1990.
The first Hubble image was around 50 percent sharper than the identical field as seen by the ground-based observatory. However, this was not as sharp as researchers had predicted, or hoped to achieve. Within a month, astronomers would learn the primary (main) mirror in the telescope, measuring nearly 8 feet in diameter, was ground incorrectly, producing out-of-focus images.
Astronauts undertook a series of space walks in 1993 to install corrective optics in the space telescope. Between 1997 and 2009, four other servicing missions to the HST upgraded the observatory, greatly increasing its capabilities over the original design.
After 25 years of delivering high-detail photographs of some of the most beautiful and distant objects in the universe, looking back at this first picture may seem anticlimactic. But, in many ways, this was one of the most important pictures ever taken by the HST.
First light for most telescopes tends to result in low-quality images that do not pack the visual punch of later photographs. However, a public relations officer, excited by the project, invited the media to be present when the image was received on the ground.
"The astronomers groaned when the media was invited. And everyone was a little perplexed and uncomfortable when the image came in because it was so out of focus. Someone said 'Is that the way it's supposed to look?' " Dave Leckrone, a deputy project scientist on the project in 1990, said.
One of the most famous - and stunning - astronomical photos of all time was imaged by the Hubble Space Telescope in 1995. This photograph of the Eagle Nebula, also known as M16, shows massive tendrils of gas forming new stars. This image was popularly known as The Pillars of Creation.
Officials managing the Hubble program believe the iconic space telescope could still be performing science until the year 2020 or beyond.
