NASA’s James Webb Telescope vs. Hubble Telescope: Comparison

James Webb Telescope and Hubble Telescope both are NASA’s powerful telescopes. Some people are saying that Webb is a replacement for Hubble space but others are saying it is a successor of Hubble. Here, I will discuss all these things and will clear everything about them including the differences.

After project delays and launch postpones, The James Webb Space Telescope has finally been launched to space in December 25, 2021. The Hubble Space Telescope was launched into low Earth orbit in April 1990, it has made more than 1.4 million observations, including tracking interstellar objects, capturing a comet colliding with Jupiter, and discovering moons around Pluto. Hubble has captured galaxies merging, probed supermassive black holes, and has helped us understand the history of our universe.

According to Webb project scientist, Klaus Pontoppidan James Webb Telescope will take amazing images, they will be better than what Hubble did. James Webb Telescope’s potential is said to be 100 times more than our beloved Hubble telescope.

James Webb Telescope Launch

Over the three decades since the famous observatory Hubble space telescope has expanded our view of the cosmos and held our attention with the stunning images it collects. What once was a faint and mysterious abyss became a detailed and colorful universe. Now, we could see stars and galaxies as they had never been seen before. If we talk about the James Webb telescope, it will do things a bit differently.

According to a NASA fact sheet with its giant gold mirror and infrared light observation tools, Webb is designed to see objects 10 to 100 times fainter than what Hubble can see. 

Comparisons between James Webb Telescope and Hubble Telescope

Let’s take one by one feature and discuss them,

1. Wavelength

The James Webb Space Telescope carries four scientific instruments and observes primarily in the infrared range that provide coverage from 0.6 to 28 microns. The instruments on Hubble see mainly in the ultraviolet and visible part of the spectrum that is why it observes only a small range in the infrared from 0.8 to 2.5 microns.

This means that Webb’s instruments will work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range.

James Webb telescope Mirrors

2. Size

The Webb telescope requires the largest mirror ever launched for astronomy. The mirror spans more than 21 feet. Webb’s mirror is made of beryllium which is a strong and lightweight metal. It’s also segmented, allowing it to fold like a drop-leaf table for launch. Each of the 18 hexagonal segments is the size of a coffee table and coated with ultra-thin gold, an ideal reflector of infrared light. Whereas Hubble’s mirror size is 8 feet.

3. Maintenance

Hubble can be repaired and upgraded while in orbit due to its location. Astronauts famously corrected Hubble’s mirror in 1993 using Canadarm. Webb will be too far from Earth to repair, which is why it has gone through unprecedented testing.

4. Orbit

Hubble orbits around the Earth at an altitude of 570 km. Webb will not orbit the Earth. It will orbit the sun at about 1.5 million kilometers away from Earth. As the Earth orbits the Sun, Webb will orbit with it, but it will stay fixed in the same spot with relation to the Earth and the Sun.

According to NASA Hubble can see the equivalent of the toddler galaxies and the Webb Telescope will be able to see the baby galaxies. The Webb’s near- and mid-infrared instruments will help study the first formed galaxies, exoplanets, and birth of stars. Because Hubble is in Earth orbit, it was able to be launched into space by the space shuttle. Webb will be launched on an Ariane 5 rocket and because it won’t be in Earth orbit, it is not designed to be serviced by the space shuttle.

Hubble Telescope

5. Light

The Webb telescope is expected to behold light from the universe’s first stars and galaxies which is beyond Hubble’s range. This light will reveal how the original stars looked 13.7 billion years ago. Whereas the Hubble telescope has starred as far back as 13.4 billion years to disclose a clumpy runt of a galaxy. That clumpy runt of a galaxy is currently the oldest and farthest object ever observed.

6. Location

The Hubble telescope circles just 330 miles overhead. The altitude was dictated by the capabilities of NASA’s space shuttles, which delivered Hubble to orbit and then made five service calls. Webb has bound for a more distant spot of 1 million miles away at what’s called the second Lagrange point (L2). This is where the gravitational forces of the Earth and sun balance, requiring minimal fuel for a spacecraft to stay put.

In simple words, it’ll be placed at 4 times the distance of the moon from the earth. Webb will constantly face the nightside of Earth as the spacecraft and planet swoop around the sun in unison.

7. Infrared Vision

As human beings, the Hubble telescope sees visible light with a little ultraviolet and infrared thrown in. But the Webb telescope visible and ultraviolet wavelengths emitted by the first stars and galaxies in their elongated, heat-emitting infrared form. JSWT scans the space through infrared signal and it’s spectrum of vision is over 10 times broad than the visible light spectrum. This is the only reason why Webb’s detectors need to run at minus 400 degrees Fahrenheit.

JSWT Wavelength - Field of Vision

8. Lifetime

Hubble was years late and millions over budget by the time it rocketed into orbit in 1990. Hubble was launched in 1990 and will remain operational as long as its instruments are functioning. Webb also is years late with huge cost overruns. The minimum expected lifetime of Webb is 10 years, but it may go beyond 10 years.

This will depend on how long its propellant will last. Its propellant is needed to keep Webb stable in its orbit. The European Space Agency is picking up the launch costs, with a French-built Ariane rocket providing Webb’s lift from French Guiana.


The Hubble telescope will always be loved for its inspiring images of our universe and will continue to collect important data for astronomers. Whereas, the Webb telescope gives us new and unique eyes of places that we have never been able to reach through its infrared field of vision.

Webb is often described as Hubble’s replacement or successor. But despite a handful of glitches over the years, Hubble’s science instruments are still going strong, and the two big scopes are set to observe together in space.

Pursuing MCA from the University of Delhi, Saurabh Saha is an experienced blogger and internet marketer. Through his popular technology blogs: TechGYD.COM &, he is helping several brands to gain exposure in front of high-quality web visitors.