Hubble vs. James Webb: How Are They Different?

Since 1958, the National Aeronautics and Space Administration (NASA) has explored the far reaches of Earth’s atmosphere and outer space. It has developed two globally known telescopes that help researchers learn about the solar system and the various entities beyond it.

The Hubble Space Telescope and the James Webb Space Telescope (JWST) have supported countless research projects and contributed innumerable discoveries to science. They are essential tools for helping humans learn what goes on in space and what the landscape outside of Earth looks like.

These two telescopes operate completely differently. Learn more about the Hubble Space Telescope and JWST and how they both expand our knowledge of the universe.

A Brief Overview of Hubble and James Webb

Hubble has been called, “the most productive science mission in the history of NASA.” It has made more than 1.5 million observations and more than 20,000 papers have been published based on its discoveries. NASA even has a tool where you can see what Hubble observed on your birthday.

The Hubble Space Telescope was designed to be more than a telescope. It needed to be a telescope that was propelled into space, floated around Earth’s atmosphere, and could be maintained while in orbit. Hubble Space Telescope launched on April 24, 1990. The Discovery shuttle carried it into space and it went into orbit the next day. Over the decades, there have been multiple service missions where astronauts improve or repair Hubble.

As Hubble took photos and made observations over the years, technology on Earth moved forward. Researchers developed more advanced telescopic tools and eventually developed the James Webb Space Telescope. JWST was launched on December 25, 2021, on an Ariane 5 rocket and was originally dubbed the “Next Generation Space Telescope.”

NASA emphasizes that JWST is not a replacement for Hubble, but rather its successor. Both play essential roles in research and have been invaluable resources for understanding space.

James Webb Telescope vs. Hubble: Technological Differences

When you look at the capabilities of Hubble and JWST, you develop an appreciation for the technology that existed in the 1980s and how far humans have come since. Here are a few key differences between Hubble and JWST that highlight how science has advanced.

Design

There are a few key features that make JWST more advanced than Hubble. The first is the use of infrared observations. New stars and planets are often hidden behind clouds of space dust. Infrared systems can see beyond this to get clearer pictures of the solar system. JWST takes pictures on an infrared spectrum while Hubble primarily uses visible light.

JWST’s primary mirror is also significantly bigger than Hubble. While Hubble’s primary mirror is 2.4 meters in diameter, Webb’s is 6.5 meters. This gives Webb a much larger field of view while also providing better resolution.

Despite being smaller, Hubble is heavier than Webb. Hubble’s mirror weighs 1,825 pounds, just short of a ton. This was possible because Hubble was manually brought into space by human astronauts. NASA realized shooting a telescope deep into space required lighter mirrors, which is where Webb gets its iconic hexagonal segments. Webb’s mirrors are made with beryllium, and each of the 18 segments weigh only 46 pounds.

Mirrors

The three differentiating factors between Webb's and Hubble’s mirrors — the size, weight, and ability to use either infrared or visible light — have a significant effect on what the telescopes can see. The segmented mirrors, placement of Webb, and its advanced tools allow it to take significantly more detailed photos than Hubble.

The universe is constantly expanding since the Big Bang 13.77 billion years ago, which means the farther something is, the older it is. NASA says that Hubble can see very young “baby galaxies” while Webb can see slightly older “toddler galaxies.” There are still countless galaxies and parts of space that are beyond their reach.

Orbits

For more than 30 years, Hubble has orbited Earth. It floats around the atmosphere around 515 kilometers above Earth’s surface. For reference, Mount Everest, one of the highest points on the planet, is only 8.9 kilometers high. The proximity to Earth allows scientists to repair Hubble when needed so it can continue making observations.

Webb, on the other hand, orbits the sun. It is approximately one million miles away from Earth and follows a similar orbital pattern. From Webb’s perspective, the sun, Earth, and the moon are always in the same place in the sky. Earth blocks the sun, preventing Webb from overheating. Because Webb is so far away, it cannot receive service from human astronauts if needed.

Capabilities and Discoveries

The power of infrared photography is immediately noticeable as soon as you compare the photos from Hubble and Webb. While Hubble’s images are beautiful, Webb’s images highlight just how much researchers were missing. This will have a significant impact on space research as scientists learn more about the universe around us.

Almost anyone can appreciate the discoveries that both telescopes have made. Hubble has been invaluable in helping researchers identify the origins of the universe and how old it may be. Before 1999, researchers thought the universe was between 7 and 20 billion years old. Hubble helped them narrow that down to 13.7 billion years — with only 200 million years of uncertainty.

Webb has also helped scientists research exoplanets, which are any planets that fall beyond the Milky Way. While billions of exoplanets may exist, Webb has helped scientists confirm the existence of over 5,600.

Impact and Significance

While Hubble has supported tens of thousands of researchers and continues to advance human knowledge of the universe, it also captured the attention of people across planet Earth and made them curious about space. Its photos show how beautiful the galaxy is and make people wonder about the planets, stars, and elements that make up the solar system and beyond.

Webb continues this legacy by showing how little humans know about space, making them excited to see what this technology, along with future telescope generations, can uncover. Webb has the potential to revolutionize our understanding of the cosmos and challenge previously held beliefs. In short, its power is just being realized.

Hubble and Webb connect the average person to space exploration with their stunning photos. Curiosity about space can spur kids to study science or encourage adults to become lifelong learners. While these telescopes are invaluable to researchers, they impact humans across the world, furthering a driver to learn more about space with each generation.