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For centuries, one of the biggest challenges in astronomy has been our planet’s atmosphere. While it helps distribute heat from the Sun and provides the pressure and oxygen we need to survive, it gets in the way of starlight.
Fluctuations in the air distort the light coming from space and mess with ground-based observations. It’s the reason the stars appear to twinkle in the night sky. They send their light our way in a more or less steady stream of photons, but it gets wiggled a little at the finish line, as it travels through the atmosphere on the way to our eyes.
Ground-based telescopes use a variety of systems including deformable mirrors and artificial laser-based reference stars to correct for atmospheric distortion in real time. They’re also often built at high altitudes, at the tops of mountains, to get above as much of the atmosphere as possible. The SOFIA Observatory (short for Stratospheric Observatory for Infrared Astronomy) went as far as strapping a telescope to a modified Boeing 747 and flying at altitudes up to 45,000 feet during observations.
But if you want truly clear images, you have to make like the crew of The Ark (streaming now on Peacock) and get off the Earth. That’s why the Hubble Space Telescope, the world’s most beloved orbiting telescope, has been the gold standard for decades. Today, Hubble celebrates its 35th birthday.
The early days of the Hubble Space Telescope
The 24,000-pound Hubble Space Telescope launched into orbit 35 years ago, on April 24, 1990, aboard the Space Shuttle Discovery. When the first data came back from above the atmosphere, scientists on the ground quickly realized something was wrong. Instead of the crisp, clear images astronomers were expecting, everything came back blurry.
Hubble’s primary mirror had a small but important flaw. The edges had been ground too flat by a fraction the width of a human hair. It was enough that the mirror couldn’t focus light correctly. Fortunately, NASA had already been working on an upgraded camera to be installed by astronauts at a later date.
Before the updated camera went into orbit, it was modified with corrective optics to balance the flaw in the mirror and return the crisp images astronomers were looking for. An array of smaller mirrors also helped to focus light from the mirror as it was sent to the telescope’s other instruments. Astronauts carried out a total of five service missions to Hubble, upgrading or repairing instruments, between 1993 and 2009.
Hubble’s 35-year legacy
While other orbiting telescopes have been launched in recent years, Hubble remains the most recognizable and longstanding orbital observatory in history.
“Hubble opened a new window to the universe when it launched 35 years ago. Its stunning imagery inspired people across the globe, and the data behind those images revealed surprises about everything from early galaxies to planets in our own solar system,” said Shawn Domagal-Goldman, acting director of the Astrophysics Division at NASA Headquarters in Washington, in a statement.
Hubble was designed to last 15 years and provide cutting edge views of the cosmos. Thirty-five years later it’s still trucking along, though it’s feeling its age. Parts have broken down and the telescope is now limping along on a single gyro, instead of its original three. That hasn’t stopped it from continuing to send back stunning new images of everything from our closest planetary neighbors to distant galaxies.
To celebrate Hubble’s 35th anniversary in orbit, NASA released a set of four new images highlighting the breathtaking capabilities of the world’s favorite telescope. The above mosaic includes a closeup of Mars (top left) as it was in late December 2024; icy clouds can be seen hovering at the poles, at a distance of 61 million miles. At upper right, outflows of radiation and stellar winds from a dense white dwarf create the sprawling beauty of the nebula NGC 2899. A star forming region in the Rosette Nebula can be seen swirling hydrogen gas and dust in the lower left; and the spiral galaxy NGC 5355 can be seen at lower right, patches of star formation punctuating its landscape and a bright bar of stars, gas, and dust spans its center.
Hubble’s three-and-a-half-decade lifetime has allowed astronomers to observe cosmic objects over extended periods to see how they change and evolve over time. In addition to peering at the very edges of the observable universe, Hubble has investigated things like seasonal changes of solar system planets, expanding supernovae, pulsars, and more.
The telescope has made more than 1.7 million observations of roughly 55,000 targets, resulting in thousands of scientific publications. More than that, it changed the way we visualize and think about the universe, and our place within it.
See the distant cosmos up close in The Ark, streaming now on Peacock.
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