It’s been 25 years since the Hubble Space Telescope was sent into orbit, and it’s still going strong. And that’s because Hubble is a very special piece of equipment unlike any other.

NASA launched Hubble on April 24, 1990, calling is the most important scientific development in astronomy since Galileo’s telescope, and it is two and a half decades, it has produced some of the most iconic images in history, according to an ABC News report.

Hubble has made 1.2 million observations in its history, and its findings have resulted in more than 12,800 scientific papers being published — demonstrating that it is one of the most successful scientific tools ever built.

The Hubble can peer so much deeper into space than ground telescopes because the Earth’s atmosphere is not obstructing it. It has used this advantage to spot distance exoplanets, massive galaxies, and spectacular supernova, sometimes billions of light years away from our own Milky Way.

The Hubble speeds around the Earth at 17,000 miles per hour, and has so far traveled a whopping 3 billion miles.

Hubble is capable of looking back 13.4 billion light years, back to a time when the universe was just expanding after the Big Bang.

Hubble sports a mirror that is 8 feet wide, and has four main instruments allowing it to view ultraviolet, visible, and near infrared light.

Without the distortion of the atmosphere, Hubble has recorded some of the most detailed images ever of deep space, leading to breakthroughs in astrophysics. One of the biggest discoveries made through the Hubble telescope was figuring out the rate of expansion of the universe.

It isn’t the first space telescope, but it is the biggest and has the most capabilities. NASA built it with help from the European Space Agency, and the Space Telescope Science Institute.

It is considered one of four of NASA’s so-called “Great Observatories,” including the Chandra X-ray Observatory, the Spitzer Space Telescope, and the Compton Gamma Ray Observatory.

Hubble was first funded all the way back in the 1970s, and originally NASA had hoped to launch it in 1983. But, as is often the case in government, there were technical problems and budget problems, and then the Challenger disaster further complicated things. However, in 1990 it finally got off the ground. Even then, it had its issues, with a problem with its main mirror that had to be corrected by a 1993 servicing mission.

It was named after Edwin Hubble, an astronomer who died in 1953. Hubble played an important role in the field of extragalactic astronomy, one of the biggest accomplishments by cosmologists in the 20th century.