Orbiting 350 miles above Earth for the past 19 years, the Hubble Space Telescope has allowed scientists to peer deep into the cosmos, sending them astonishing images of newborn stars and colliding galaxies from the earliest moments of the universe.
But there's more than meets the eye for this ground-breaking telescope.
How much do you really know about the beloved Hubble? Here are 10 things you probably don't know yet.
1. NASA's "Comeback Kid" started out as a failure.
Now, it's an international sensation, widely known as the "people's telescope." But that wasn't always the case.
"It is now viewed as this unqualified success that has transformed our knowledge of the universe," said Roger Launius, senior curator for the Smithsonian's National Air and Space Museum in Washington, D.C. "I've heard it compared to, in terms of its impacts, the same level of change as when Galileo first turned his homemade telescope on Jupiter in 1609."
But "the telescope began life being viewed as a flop," he said.
A measuring error in the grinding of the mirror prevented the telescope from focusing light properly. As a result, soon after its launch in April 1990, the photos sent back to Earth were fuzzy disappointments.
The mirror was ever so slightly the wrong shape, which caused light that bounced off the center of the mirror to focus in a different place than the light bouncing off the edge. The flaw was minuscule -- 1/50th the thickness of a sheet of paper -- but it made a significant difference.
"[There were] NASA scientists that stood up and said, "It's a total loss," Launius said of Hubble's early days.
Members of Congress, including Sen. Barbara Mikulski, D-Md., who was, and still is, a big NASA supporter, were livid that this had taken place.
"This was such a failure, to the tune of $3 billion," he said.
Thankfully, the telescope's first servicing mission in December 1993 was a success. After spending 11 months training for what is considered to be one of the most complex missions, astronauts installed a series of small mirrors to fix the flaw.
"They had figured out some ways to work around that problem," Launius said. "But it took a while to generate some of the images that we've seen."
2. Like us, Hubble can't look directly at the sun.
Hubble has photographed every planet in the solar system, with one exception: Mercury.
The solar system's innermost planet is too close to the sun for Hubble to observe. The sun's bright light would permanently damage its optics and electronics.
Mercury's angular separation from the sun is always less than 28 degrees, which means that it's never out of the sun's glare and, therefore, off limits for the Hubble.
3. It's a pop-culture icon.
Hubble and its images have also had their share of cameo appearances in Hollywood flicks and TV shows.
When "Naked Gun 2 1/2" came out in 1991, Hubble was still a national laughingstock.
In the movie, it was pictured in the Blue Moon Cafe on a wall of failures, smack in the middle of the Titanic and the Hindenberg.
Imagery from Hubble has also been spotted in the movies "Happy Feet" and "Contact."
For the album cover of its 2000 release "Binaura," Pearl Jam used an image of Hubble's "Hourglass Nebula."