Quick Facts (2024)

What areas of science will Webb explore?

Webb has several key areas of scientific interest:

• Searching for the first galaxies that formed in the early universe

• Studying galaxies near and far to inform the evolution of galaxies

• Observing the life cycles of stars, from the first stellar nurseries to the formation of planetary systems

• Measuring physical and chemical properties of planetary systems, including our own solar system, and investigating the potential for life on planets that orbit other stars

Webb also has the capacity to reveal completely unexpected aspects of our universe, and forge additional questions that can be addressed in future observation cycles and by future missions and observatories.

Who decides what the telescope observes?

On a yearly basis, anyone in the world can apply for time to use the telescope for a specific investigation through the General Observers (GO) program. For each year of observations, referred to as a cycle, proposals are evaluated for scientific merit and viability by a Time Allocation Committee composed of members of the worldwide astronomy community, using adual-anonymous reviewprocess. Selected programs for each cycle are then announced publicly. Webb’s observation schedules are published online weekly.

Who has access to data from Webb?

As a NASA mission, all data from Webb will be publicly available online to anyone in the world through the Mikulski Archive for Space Telescopes (MAST). For some programs, principal investigators are granted a period of exclusive access to their data, most commonly for 12 months. Following the exclusive access period, the data become public.

What wavelengths of light can Webb observe?

Webb is optimized to observe infrared light, which is redder (has longer wavelengths) than human eyes can detect. Webb is able to measure light from 0.6 to 27.9 microns, a wavelength range that covers orange visible light through mid-infrared.

The shortest wavelength in this range is set by the gold coating on the primary mirror. The longest wavelength is set by the sensitivity of the detectors in MIRI (the Mid-Infrared Instrument).

The wavelength ranges of the individual instruments are:

1. NIRCam (Near-Infrared Camera) : 0.6–5 microns

2. NIRSpec (Near-Infrared Spectrograph) : 0.6–5.3 microns

3. MIRI (Mid-Infrared Instrument) : 4.9–27.9 microns

4. NIRISS (Near-Infrared Imager and Slitless Spectrograph) : 0.6–5 microns

How does infrared astronomy help us better understand the universe?

Infrared light allows us to see details in the universe and determine the composition of distant objects, from exoplanets to galaxies. For example, we can gain new insights into relatively cool objects like planets and their atmospheres, which emit most of their light at infrared wavelengths. With its longer wavelengths, infrared light can also penetrate dense star-forming clouds, whose dust blocks most of the light detectable by visible light telescopes like Hubble. Finally, infrared light allows us to study some of the first galaxies to form after the big bang. Through a process called cosmological redshift, light from galaxies that is emitted in shorter ultraviolet and visible wavelengths is stretched to the longer wavelengths of infrared light by the expansion of the universe. Learn more about infrared astronomy.

What is spectroscopy and how does Webb utilize it?

Spectroscopy is the study and interpretation of a celestial object’s spectrum. A spectrum is light spread out by wavelength, like in a rainbow. By looking at the patterns in brightness at different wavelengths, we can learn about the composition, temperature, density, motion, and other characteristics of objects and materials in space, including planets, stars, nebulae, and galaxies. Explore theSpectroscopy 101 seriesfor more details.

Webb has different types of spectrographs—instruments that spread out the light into a spectrum so scientists can measure the that the brightness of each individual wavelength. Each is designed for a slightly different purpose. All four of Webb’s scientific instruments (MIRI, NIRCam, NIRSpec, and NIRISS) have spectroscopy modes.

How does Webb study exoplanets? How can Webb study the chemical makeup of exoplanets’ atmospheres?

An exoplanet is a planet that orbits a star other than the Sun.

Webb can detect and characterize fully-formed planets, planets in the process of forming, and proto-planetary disks orbiting other stars in the Milky Way. Webb images debris disks and large planets far from their host stars using its coronagraphs; detects and provides data for models of the composition and structure of exoplanet atmospheres; and helps astronomers understand the influence of host stars on their planets. These studies provide insight into the diversity, formation, evolution, and potential habitability of planets and planetary systems in our galaxy.

Webb studies the atmospheres of exoplanets using spectra, determining which elements and molecules are present and what they indicate about each world, including its potential to support life.

Learn more how Webb can study exoplanets.

Check out Webb’s exoplanet observations.

How does Webb study galaxies? What can the observations tell us?

A galaxy is a collection of stars, gas, dust, and dark matter bound together by gravity. The smallest galaxies may contain only a few hundred thousand stars, while the largest galaxies have thousands of billions of stars.

Webb studies galaxies at all stages of development and ages of cosmic history. Webb captures light from the first galaxies in their nascent stages of development; measures star formation rates within galaxies near and far; and creates detailed maps of gas, dust, and even dark matter in our local universe. Webb’s studies are designed to help us understand the diversity of galaxy composition and structure over space and time; how galaxies form, interact, and change; and how supermassive black holes and their host galaxies influence each other.

Learn more about Webb’s study of galaxy formation.

Check out Webb’s observations of galaxies.

Can Webb observe objects in our own Solar System?

Yes. Webb’s infrared capabilities allow astronomers to characterize the atmospheres and surfaces of planets, moons, comets, asteroids, and Kuiper Belt objects in the outer solar system. Because Webb cannot point toward the Sun, it can only observe objects beyond the orbit of Earth: the Sun, Mercury, Venus, Earth, or Earth’s moon.

Find out more about how Webb will study our solar system.

Check out Webb’s solar system discoveries.

How far back in time can Webb see?

Webb is able to observe some of the first galaxies, which formed a few hundred million years after the big bang. The big bang, the beginning of the universe, is currently estimated to have occurred roughly 13.8 billion years ago.

Check out Webb’s observations of early galaxies.

What is redshift? How can we tell the difference between an intrinsically red galaxy and one that has been redshifted?

Cosmological redshift is the stretching of light to longer wavelengths over time as the universe expands.

Webb’s sensitivity to infrared light allows us to see the ancient light of the first galaxies, which is redshifted as it travels through space over billions of years. Light from those galaxies that was emitted as ultraviolet and visible light has stretched to the longer wavelengths of infrared light.

From color alone, it can be difficult to tell the difference between a galaxy with redshifted light and one that is red for other reasons—for example, because it contains large amounts of dust. That is why astronomers spread out the galaxies’ light into spectra to look for patterns of spectral features. Every element or molecule produces a unique pattern of features in a spectrum of light. Researchers can measure the patterns for each element or molecule on Earth, then compare them to the shifted patterns of features in the spectra of distant objects. The amount of shift allows them to determine objects’ exact redshifts.

I see that Webb looks at some of the same objects that Hubble already has. How does Webb work with Hubble?

When Webb observes objects that Hubble has also observed, we can learn a lot by comparing different kinds of light observed from the same object. Webb's infrared capabilities reveal different details, deepening our understanding of celestial objects.

For example, the Hubble and Webb views of the Pillars of Creation in the Eagle Nebula show us different aspects of the star-forming region. In Hubble’s visible light observations, forming stars are inside dense cocoons of gas and dust, which block their visible light from reaching the telescope. In Webb’s near-infrared observations, infrared light shines through all but the densest dust, revealing many stars inside and around the pillars.

Has Webb taken deep field images? Will it observe the same deep fields as Hubble?

There are several groups of researchers who are carrying out deep field programs with Webb. Some of those surveys overlap with deep fields taken by the Hubble Space Telescope.

For example, the JWST Advanced Deep Extragalactic Survey (JADES) has captured images and spectra of the GOODS-North and GOODS-South fields. GOODS-North contains the original Hubble Deep Field. GOODS-South contains the Hubble Ultra Deep Field, which is the deepest, most sensitive image of the sky ever taken with Hubble.

The Next Generation Deep Extragalactic Exploratory Public (NGDEEP) Survey also targets the two regions that make up theHubble Ultra Deep Field.

How does Webb work with other telescopes?

Each observatory has a unique set of capabilities determined by numerous factors, including the instruments on board, the wavelength range it is designed for, and its various observing modes). Combining data from different observatories enhances what we can learn about everything in the universe.

Webb’s observations complement those of the Hubble Space Telescope and the upcoming Nancy Grace Roman Space Telescope. Hubble and Webb observe different ranges of light along the electromagnetic spectrum. Hubble can capture ultraviolet, visible, and near-infrared light, while Webb specializes in observing near- and mid-infrared light. For example, observations with Hubble can tell us about a galaxy’s young, hot stars, while observations with Webb can tell us about the structure of the galaxy’s cool dust.

Roman’s wider field of view will produce expansive surveys of the sky, identifying objects that can be followed up with targeted observations from Webb and Hubble.

Agreements between observatories allow researchers to submit joint proposals to use Webb and ALMA, Chandra, XMM-Newton, Hubble, and the ground-based NASA-Keck and National Science Foundation’s NOIRLab telescopes.

Where can I find the latest science news from Webb?

The News Office at STScI works with NASA to promote newsworthy peer-reviewed scientific findings in press releases. The latest news releases can be found at webbtelescope.org/news.

Where is Webb located?

Webb orbits the Sun from a location near the second Sun-Earth Lagrange point (L2), approximately 1½ million kilometers(1 million miles) from Earth.

How much of the sky can Webb see at any given time?

Over the course of six months, as Webb orbits the Sun with Earth, it has the ability to observe almost any point in the sky. Webb’s field of regard is limited to a 50-degree swath of the celestial sphere: About 39% of the sky is potentially visible to Webb at any given time.

How we do communicate with Webb?

Webb’s Mission Operations Center is at the Space Telescope Science Institute (STScI) in Baltimore, Maryland. STScI engineers send commands to Webb and continuously monitor the health of the telescope.

Traveling at the speed of light, it takes about five seconds for commands and data to travel between Webb and Earth. All communications are routed through NASA’s Deep Space Network, with ground stations located in Canberra, Australia; Madrid, Spain; and Goldstone, California.

Webb can downlink at least 57.2 gigabytes of recorded science data each day, with a maximum data rate of 28 megabits per second.

S-band frequencies are used for command uplink, low-rate telemetry downlink, and ranging. Ka-band frequencies are used for high-rate downlink of science data and telemetry.

Can we service Webb?

No. Unlike Hubble, Webb is not designed to be serviced. To meet Webb’s science goals, the telescope has to be far away from the heat of Earth. This is why the telescope had to be tested so thoroughly before launch. To ensure a successful mission,NASA has engineered Webb so that all critical subsystems are dual or will degrade gracefully with age. For example, NIRCam (the Near Infrared Camera) has two identical camera systems so that optical quality can be maintained even if one fails.

This isn’t the first NASA mission that is unserviceable. Other space telescopes, such as Spitzer and Herschel, successfully completed their missions in unserviceable orbits.

What are the key components of the Webb telescope?

Webb’s key components include a 6.6-meter (21.7-foot) diameter segmented, primary mirror to collect infrared light, four scientific instruments to conduct its ambitious science operations, and a sunshield to keep the mirror and instruments cold. Webb’s science instruments are housed behind the mirror, on the cold side of the telescope, separated by the sunshield from the communications and control technology. The solar panels, communications antenna, navigation system, and electronic systems reside on the hot side of the telescope, which faces the Sun and Earth.

How big is the Webb telescope and its mirror?

Webb’s primary mirror towers more than two stories high and once unfurled, its protective sunshield measures about the size of a tennis court. On Earth, Webb tips the scales at more than 13,000 pounds—just about equal to the weight of an adult African elephant.The entire observatory is 8 meters high.

Why does Webb need a sunshield?

To accurately and precisely detect faint infrared light from distant objects in the universe, Webb must be shielded from the strong infrared light emanating nearby from the Sun, Earth, and Moon. The sunshield’s five layers block the light from these nearby objects.

Which instruments are on the Webb telescope and what do they do?

Webb has four scientific instruments, NIRCam (the Near-Infrared Camera), NIRSpec (the Near-Infrared Spectrograph), NIRISS (the Near-Infrared Imager and Slitless Spectrograph), and MIRI (the Mid-Infrared Instrument). Each of these instruments uses infrared detectors to capture light from different objects in space.

Why does Webb’s mirror look like that?

To perform the science Webb was designed to do, including detecting the most distant galaxies, Webb’s mirror needed to be large and strong, but light enough to launch into space. Beryllium was ideal for this purpose. The telescope team also designed segmented mirrors so the mirror could be folded up to fit inside the launch vehicle. The hexagonal shape of each segment allows for a roughly circular, segmented mirror with "high filling factor and six-fold symmetry." High filling factor means the segments fit together without gaps. If the segments were circular, there would be gaps between them. The segments are coated in gold because it reflects red to mid-infrared light extremely well. (Light that is absorbed by the mirror cannot be reflected into the instruments and will not appear in images or spectra.)

How did Webb deploy in space?

To fit inside the launch vehicle, Webb needed to fold upon itself, then unfurl in a series of complicated steps on the way to its orbit location. Webb’s deployment in space involved unfolding the sunshield and mirrors, a process that was carefully conducted over nearly a month. The sequence is best explained visually in this deployment animation.

Can Webb’s sunshield and mirror withstand micrometeoroid impacts?

Both Webb’s sunshield and mirror wereengineered to withstandbombardment of dust-sized particles flying at extreme velocities in the micrometeoroid environment at its orbit around Sun-Earth L2. While the telescope was being built, engineers used a combination of simulations and actual test impacts on mirror samples to get a clearer idea of how to fortify the observatory for operation in orbit.Micrometeoroid strikes are an unavoidable aspect of operating spacecraft, which routinely sustain many impacts over the course of long and productive science missions in space.

What is the expected lifespan of the Webb telescope?

Webb was designed for a mission of at least five years, with a goal of 10 years. However, after a successful launch and the completion of telescope commissioning, the Webb team determined the observatory should have enough propellant to allow support of science operations in orbit for more than 20 years. Other factors, like instrument degradation, may limit mission lifetime beyond 20 years.

When was the James Webb Space Telescope launch?

Webb launched from the Guiana Space Centre (Le Centre Spatial Guyanais, CSG) in Kourou, French Guiana, onboard an Ariane 5 rocket provided by the European Space Agency on December 25, 2021 at 7:20 am EST (1220 GMT).

Where can I find more information about Webb's history?

Even before Hubble’s launch in 1990, astronomers began posing the question: “What is the next step?” It was then the idea of Webb was born. Dive into the full project history.

Where can I find all of Webb’s official high-resolution processed imagery and data?

Science data and images processed by the science visuals developers at STScI are published to our online image gallery. Each image page, for example, the Pillars of Creation, has all available download options along the left-hand side.

Why do I see Webb images online that aren’t on your official site?

Webb is one of NASA’s most anticipated and exciting missions. Once the telescope began full operations, amateur and professional scientists alike were eager to explore the data Webb was sending back. Because some of Webb’s observations are publicly available online at the Mikulski Archive for Space Telescopes (MAST), and eventually all Webb data will be available on MAST, anyone who is interested can create and publish their own processed images.

STScI has a team of scientists, science visuals developers, educators, and other communication specialists who work together to choose and process images associated with science discoveries, and create news packages to contextualize their significance. This process takes time and it's not done for every single Webb observation. On this official science outreach website, we only publish the images that we create for Webb news and outreach efforts.

Why do stars in Webb’s images have spikes?

These are called diffraction spikes. In Webb images, diffraction spikes appear when light interacts with the primary mirror and the struts that support the secondary mirror. Learn more about how this happens.

How are Webb images created?

All of Webb’s images begin as black and white exposures. Science visuals developers at STScI follow a detailed set of specific steps to highlight both the science and beauty of Webb imagery, and create the gorgeous visuals the world has now come to know in official Webb press releases.

Where do I go to find new images and other content?

As the deep-dive science website for the Webb mission, STScI’s science outreach website, webbtelescope.org, hosts Webb’s science discoveries and official image releases. Our Resource Gallery is regularly updated, and our social media accounts immediately post as new images or science releases are published. You can also sign up to receive the latest news, images, and discoveries from STScI’s telescopes, including Webb, directly to your inbox.

Where can I find Webb’s first full-color images?

Webb’s first full-color images and spectra can be found in our online Gallery.

Do I need permission to reproduce Webb images? What is the policy for using Webb images and data?

Data and observations captured with Webb are in the public domain, so they can be used without permission. Unless otherwise stated, images, videos, and content in the Resource Gallery are copyright-free. When crediting Webb images, it’s required you acknowledge the image source by including the "Credit" that appears on the image download page.

Please see our Content Use Policy for more information.

Last updated: July 19, 2023