Hubble Space Telescope turns 25 | CNN

The Hubble Space Telescope was launched April 24, 1990, from Kennedy Space Center, Florida, aboard the space shuttle Discovery. NASA calls Hubble the "most significant advance in astronomy since Galileo's telescope." Hubble has given us new, better views of our solar system and has taken us hundreds of light years away to the edge of the universe.

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Hubble has given us many images of our neighbor Mars. This image was taken in 2003 when Mars made its closest approach in nearly 60,000 years. On August 27, 2003, the two worlds were only 34.6 million miles apart from center to center. By contrast, Mars can be about 249 million miles away from Earth.

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Hubble snapped this image in 2007 of Ganymede appearing to peek out from beneath Jupiter. Ganymede is the largest moon in our solar system and it's even bigger than Mercury.

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Hubble captured this image of Saturn in 2004, a view so sharp that some of the planet's smaller rings are visible.

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Hubble tracked clouds on Uranus in this image taken in 1997. The image is a composite of three near-infrared images. The planet's rings are prominent in the near infrared. Eight of Uranus' 27 moons can be seen in both images. Uranus is about 1.75 billion miles from Earth.

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Hubble captured this image of the distant blue-green world Neptune in 2005. Fourteen different colored filters were used to help scientists learn more about Neptune's atmosphere. Neptune is about 2.8 billion miles from Earth.

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Hubble discovered four of Pluto's five moons. In 2005: Nix and Hydra were found. Hubble discovered Kerberos in 2011 and Styx in 2012. The new discoveries joined Pluto's large moon, Charon, which was discovered in 1978. Styx was found by scientists using Hubble to search for potential hazards for the New Horizons spacecraft which will fly by Pluto in July 2015. Pluto is about 2.9 billion miles from Earth.

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The Orion Nebula is 1,500 light years from Earth located in Orion's Belt in the constellation Orion. It's one of the brightest nebulae and on a clear, dark night -- it's visible to the naked eye. The nebula is Earth's nearest star-forming region.

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The iconic Horsehead Nebula is a favorite target for astronomers. Look carefully and you'll see what looks like the head of horse rising into the stars. This Hubble image captures the nebula in infrared wavelengths. The nebula is 1,600 light years from Earth.

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The Cat's Eye Nebula is a bunch of glowing gases kicked out into space by a dying star. This Hubble Space Telescope image shows details of structures including jets of high-speed gas and unusual knots of gas. This color picture is a composite of three images taken at different wavelengths. The nebula is estimated to be 1,000 years old. It's about 3,000 light years from Earth in the constellation Draco.

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The Bug, or Butterfly Nebula looks like a butterfly with its wings stretching across the galaxy. It's actually a cloud of roiling gas shed by a dying star. Scientists say the gas is more than 36,000 degrees Fahrenheit and is expanding into space at more than 600,000 miles an hour. This image was taken with Hubble's Wide Field Camera 3, a camera installed on Hubble during its May 2009 upgrade by shuttle astronauts. The nebula is about 3,800 light years away in the constellation Scorpius.

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Astronomers combined several Hubble images taken in 2014 to create an upgraded view of the Hubble's iconic 1995 "Pillars of Creation" image. The new image shows a wider view of the pillars, which stretch about 5 light-years high. The pillars are part of a small region of the Eagle Nebula, which is about 6,500 light years from Earth.

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This huge nebula is 7,500 light years from Earth in the constellation Carina. It's one of the largest and brightest nebulas and is a nursery for new stars. It also has several stars estimated to be at least 50 to 100 times the mass of our Sun, including Eta Carinae, one of the brightest stars known and one of the most massive stars in the Milky Way Galaxy.

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One of the closest neighbors to our own Milky Way, the Andromeda Galaxy, can be seen with the naked eye if you know where to look on a clear, dark night. In 2012, scientists using data from Hubble predicted Andromeda would collide with the Milky Way in about four billion years. Andromeda is 2.5 million light years from Earth.

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The Cigar Galaxy is 12 million light years away. It gets its name from its shape: From Earth it looks like an elongated elliptical disc.

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It's called one of the most photogenic galaxies: The Sombrero Galaxy looks like the giant broad rim of a Mexican hat sitting out among the stars. It can be spotted using a small telescope. It's about 28 million light years from Earth.

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This group of galaxies is about 290 million light years from Earth. It's named for its discoverer, French astronomer Edouard Stephan, who first spotted it in 1877.

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Hubble captured this image of a group of interacting galaxies called Arp 273. The bigger galaxy has a center disk that is distorted into a rose-like shape by the pull from its partner below.

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In 2004, astronomers unveiled the deepest portrait of the visible universe ever taken to date. Called the Hubble Ultra-Deep Field, the million-second-long exposure shows the first galaxies to emerge shortly after the Big Bang. The image shows an estimated 10,000 galaxies. In 2012, astronomers assembled an upgraded image called the Hubble eXtreme Deep Field. It combined 10 years of Hubble Space Telescope photographs taken of a patch of sky at the center of the original Hubble Ultra-Deep Field. The new image contains about 5,500 galaxies.

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Stunning images from the Hubble telescope

Story highlights

The Hubble Space Telescope is 25

NASA calls Hubble one of the most productive scientific instruments ever built

CNN —

It’s up there right now – flying about 340 miles over the Earth and circling us every 97 minutes. It’s a telescope – in the sky. Just think about that for a bit.

It’s called the Hubble Space Telescope. The telescope itself is not really much to look at. If you could see it right now you might think it’s just a big shiny, silver bucket with two gangly solar arms and a couple of dish antennae. It’s about the size of a school bus and weighs about as much as two elephants.

But that silver bucket is pure gold for astronomers. It’s made such a big impact that NASA, the space agency with a fleet of space probes out there taking amazing pictures, calls Hubble the “most significant advance in astronomy since Galileo’s telescope.”

Not bad for a 25-year-old floating bucket.

Hubble didn’t start out winning high marks. It was launched on April 24, 1990, aboard the space shuttle Discovery from Kennedy Space Center, Florida. The next day, it was released into space, but scientists soon realized they had a big problem. The telescope’s primary mirror had a flaw: Its outer edge was ground too flat by a depth of 2.2 microns – that’s about one-50th the thickness of a human hair.

The images that were expected to dazzle the world were fuzzy.

Hubble became the butt of late-night talk show jokes.

But in December of 1993, shuttle Endeavour astronauts repaired the telescope.

The late-night jokes stopped. And to quote NASA: “Our view of the universe and our place within it has never been the same.”

So why is Hubble so special? Because it’s on what NASA calls “the ultimate mountaintop.” Sitting high above the distortion of Earth’s atmosphere, far away from our light-polluted cities and hovering far away from clouds and storms, Hubble has “an unobstructed view of the universe.”

Hubble Facts

The Hubble Space Telescope is named after American astronomer Edwin P. Hubble

Hubble is a joint project between NASA and the European Space Agency

Scientists have used that vantage point to make groundbreaking observations about planets, stars, galaxies and to reveal parts of our universe we didn’t know existed. The telescope has made more than 1 million observations, and astronomers have used Hubble data in more than 12,800 scientific papers, “making it one of the most productive scientific instruments ever built,” according to NASA.

Zoltan Levay works in the Office of Public Outreach at the Space Telescope Science Institute at Johns Hopkins University in Baltimore.

“All the (Hubble) observations are planned here,” Levay told CNN. “We get all of the science data from the telescope and provide that data to the astronomers around the world.”

Levay oversees the production of the images that are used to illustrate and to publicize the work done by scientists using Hubble. So when someone using Hubble makes a big discovery, Levay’s team helps find the right image to illustrate the results. “We take the same data the astronomers use and we produce the pictures.”

If you’re a photographer or an astronomer – or both – you may be a bit jealous right now.

“It’s been rewarding and a challenge and a roller coaster,” Levay said.

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Levay contributed an interview for a new book marking the 25th anniversary of Hubble’s launch: “Expanding Universe. Photographs from the Hubble Space Telescope.”

He says the hardest part of his job is selecting the best photos from the thousands created by Hubble. “It’s a challenge to pick out what one would consider the best,” he said.

Here’s how Hubble creates its amazing photographs: It uses mirrors to gather lots of light from far out into space and then focuses that light on the telescope’s cameras and other instruments. These cameras aren’t like the digital ones in our smartphones that we use to take selfies or even like old cameras that use photographic film.

Instead, Hubble captures light in many different wavelengths using these cameras and instruments:

• Wide Field Camera 3 (WFC3) sees three different kinds of light: near-ultraviolet, visible and near-infrared.

• Cosmic Origins Spectrograph (COS) sees exclusively in ultraviolet light.

• Advanced Camera for Surveys (ACS) sees visible light.

• Space Telescope Imaging Spectrograph (STIS) sees ultraviolet, visible and near-infrared light.

• Near Infrared Camera and Multi-Object Spectrometer (NICMOS) is Hubble’s heat sensor. It’s sensitive to infrared light and lets scientists look for objects hidden by interstellar dust.

• Fine Guidance Sensors (FGS) are used to keep Hubble pointed in the right direction.

Eventually, Hubble will stop working. NASA had hoped to use a space shuttle to bring it home for a museum exhibit, but the telescope outlived the shuttle program. Now, NASA says it’s studying various options for its superstar telescope after it shuts down.

But Hubble fans shouldn’t worry yet. “We expect Hubble to be in the sky for quite a while, around until the 2030s,” NASA spokeswoman Felicia Chou told CNN in an email.

NASA already has plans to launch a new space-based instrument, the James Webb Space Telescope, in 2018.