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10 Frequently Asked Questions About the James Webb Space Telescope

Got basic questions about the James Webb Space Telescope and what amazing things we’ll learn from it? We’ve got your answers right here! 

The James Webb Space Telescope, or Webb, is our upcoming infrared space observatory, which will launch in 2021. It will spy the first luminous objects that formed in the universe and shed light on how galaxies evolve, how stars and planetary systems are born, and how life could form on other planets.

1. What is the James Webb Space Telescope?

Our James Webb Space Telescope is a giant space telescope that observes infrared light. Rather than a replacement for the Hubble Space Telescope, it’s a scientific successor that will complement and extend its discoveries.

Being able to see longer wavelengths of light than Hubble and having greatly improved sensitivity will let Webb look further back in time to see the first galaxies that formed in the early universe, and to peer inside dust clouds where stars and planetary systems are forming today.

2. What are the most exciting things we will learn?

We have yet to observe the era of our universe’s history when galaxies began to form. 

We have a lot to learn about how galaxies got supermassive black holes in their centers, and we don't really know whether the black holes caused the galaxies to form or vice versa.

We can't see inside dust clouds with high resolution, where stars and planets are being born nearby, but Webb will be able to do just that. 

We don't know how many planetary systems might be hospitable to life, but Webb could tell whether some Earth-like planets have enough water to have oceans.

We don't know much about dark matter or dark energy, but we expect to learn more about where the dark matter is now, and we hope to learn the history of the acceleration of the universe that we attribute to dark energy. 

And then, there are the surprises we can't imagine!

3. Why is Webb an infrared telescope?

By viewing the universe at infrared wavelengths with such sensitivity, Webb will show us things never before seen by any other telescope. For example, it is only at infrared wavelengths that we can see the first stars and galaxies forming after the Big Bang. 

And it is with infrared light that we can see stars and planetary systems forming inside clouds of dust that are opaque to visible light, such as in the above visible and infrared light comparison image of the Carina Nebula.

4. Will Webb take amazing pictures like Hubble? Can Webb see visible light?

YES, Webb will take amazing pictures! We are going to be looking at things we've never seen before and looking at things we have seen before in completely new ways.

The beauty and quality of an astronomical image depends on two things: the sharpness and the number of pixels in the camera. On both of these counts, Webb is very similar to, and in many ways better than, Hubble. 

Additionally Webb can see orange and red visible light. Webb images will be different, but just as beautiful as Hubble's. Above, there is another comparison of infrared and visible light Hubble images, this time of the Monkey Head Nebula.

5. What will Webb's first targets be?

The first targets for Webb will be determined through a process similar to that used for the Hubble Space Telescope and will involve our experts, the European Space Agency (ESA), the Canadian Space Agency (CSA), and scientific community participants.

The first engineering target will come before the first science target and will be used to align the mirror segments and focus the telescope. That will probably be a relatively bright star or possibly a star field.

6. How does Webb compare with Hubble?

Webb is designed to look deeper into space to see the earliest stars and galaxies that formed in the universe and to look deep into nearby dust clouds to study the formation of stars and planets.

In order to do this, Webb has a much larger primary mirror than Hubble (2.5 times larger in diameter, or about 6 times larger in area), giving it more light-gathering power. It also will have infrared instruments with longer wavelength coverage and greatly improved sensitivity than Hubble. 

Finally, Webb will operate much farther from Earth, maintaining its extremely cold operating temperature, stable pointing and higher observing efficiency than with the Earth-orbiting Hubble.

7. What will Webb tell us about planets outside our solar system? Will it take photos of these planets?

Webb will be able to tell us the composition of the atmospheres of planets outside our solar system, aka exoplanets. It will observe planetary atmospheres through the transit technique. A transit is when a planet moves across the disc of its parent star. 

Webb will also carry coronographs to enable photography of exoplanets (planets outside our solar system) near bright stars (if they are big and bright and far from the star), but they will be only "dots," not grand panoramas. Coronographs block the bright light of stars, which could hide nearby objects like exoplanets.

Consider how far away exoplanets are from us, and how small they are by comparison to this distance! We didn’t even know what Pluto really looked like until we were able to send an observatory to fly right near it in 2015, and Pluto is in our own solar system!

8. Will we image objects in our own solar system?

Yes! Webb will be able to observe the planets at or beyond the orbit of Mars, satellites, comets, asteroids and objects in the distant, icy Kuiper Belt.

Many important molecules, ices and minerals have strong characteristic signatures at the wavelengths Webb can observe. 

Webb will also monitor the weather of planets and their moons. 

Because the telescope and instruments have to be kept cold, Webb’s protective sunshield will block the inner solar system from view. This means that the Sun, Earth, Moon, Mercury, and Venus, and of course Sun-grazing comets and many known near-Earth objects cannot be observed.

9. How far back will Webb see? 

Webb will be able to see what the universe looked like around a quarter of a billion years (possibly back to 100 million years) after the Big Bang, when the first stars and galaxies started to form.

10. When will Webb launch and how long is the mission?

Webb will launch in 2021 from French Guiana on a European Space Agency Ariane 5 rocket. 

Webb’s mission lifetime after launch is designed to be at least 5-1/2 years, and could last longer than 10 years. The lifetime is limited by the amount of fuel used for maintaining the orbit, and by the possibility that Webb’s components will degrade over time in the harsh environment of space.

Looking for some more in-depth FAQs? You can find them HERE.

Learn more about the James Webb Space Telescope HERE, or follow the mission on Facebook, Twitter and Instagram.

IMAGE CREDITS Carina Nebula: ESO/T. Preibisch Monkey Head Nebula: NASA, ESA, the Hubble Heritage Team (STScI/AURA), and J. Hester

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Infrared is Beautiful

Why was James Webb Space Telescope designed to observe infrared light? How can its images hope to compare to those taken by the (primarily) visible-light Hubble Space Telescope? The short answer is that Webb will absolutely capture beautiful images of the universe, even if it won’t see exactly what Hubble sees. (Spoiler: It will see a lot of things even better.)

The James Webb Space Telescope, or Webb, is our upcoming infrared space observatory, which will launch in 2019. It will spy the first luminous objects that formed in the universe and shed light on how galaxies evolve, how stars and planetary systems are born, and how life could form on other planets.

What is infrared light? 

This may surprise you, but your remote control uses light waves just beyond the visible spectrum of light—infrared light waves—to change channels on your TV.

Infrared light shows us how hot things are. It can also show us how cold things are. But it all has to do with heat. Since the primary source of infrared radiation is heat or thermal radiation, any object that has a temperature radiates in the infrared. Even objects that we think of as being very cold, such as an ice cube, emit infrared.

There are legitimate scientific reasons for Webb to be an infrared telescope. There are things we want to know more about, and we need an infrared telescope to learn about them. Things like: stars and planets being born inside clouds of dust and gas; the very first stars and galaxies, which are so far away the light they emit has been stretched into the infrared; and the chemical fingerprints of elements and molecules in the atmospheres of exoplanets, some of which are only seen in the infrared.

In a star-forming region of space called the 'Pillars of Creation,' this is what we see with visible light:

And this is what we see with infrared light:

Infrared light can pierce through obscuring dust and gas and unveil a more unfamiliar view.

Webb will see some visible light: red and orange. But the truth is that even though Webb sees mostly infrared light, it will still take beautiful images. The beauty and quality of an astronomical image depends on two things: the sharpness of the image and the number of pixels in the camera. On both of these counts, Webb is very similar to, and in many ways better than, Hubble. Webb will take much sharper images than Hubble at infrared wavelengths, and Hubble has comparable resolution at the visible wavelengths that Webb can see.

Webb’s infrared data can be translated by computer into something our eyes can appreciate – in fact, this is what we do with Hubble data. The gorgeous images we see from Hubble don’t pop out of the telescope looking fully formed. To maximize the resolution of the images, Hubble takes multiple exposures through different color filters on its cameras.

The separate exposures, which look black and white, are assembled into a true color picture via image processing. Full color is important to image analysis of celestial objects. It can be used to highlight the glow of various elements in a nebula, or different stellar populations in a galaxy. It can also highlight interesting features of the object that might be overlooked in a black and white exposure, and so the images not only look beautiful but also contain a lot of useful scientific information about the structure, temperatures, and chemical makeup of a celestial object.

This image shows the sequences in the production of a Hubble image of nebula Messier 17:

Here’s another compelling argument for having telescopes that view the universe outside the spectrum of visible light – not everything in the universe emits visible light. There are many phenomena which can only be seen at certain wavelengths of light, for example, in the X-ray part of the spectrum, or in the ultraviolet. When we combine images taken at different wavelengths of light, we can get a better understanding of an object, because each wavelength can show us a different feature or facet of it. 

Just like infrared data can be made into something meaningful to human eyes, so can each of the other wavelengths of light, even X-rays and gamma-rays.

Below is an image of the M82 galaxy created using X-ray data from the Chandra X-ray Observatory, infrared data from the Spitzer Space Telescope, and visible light data from Hubble. Also note how aesthetically pleasing the image is despite it not being just optical light:

Though Hubble sees primarily visible light, it can see some infrared. And despite not being optimized for it, and being much less powerful than Webb, it still produced this stunning image of the Horsehead Nebula.

It’s a big universe out there – more than our eyes can see. But with all the telescopes now at our disposal (as well as the new ones that will be coming online in the future), we are slowly building a more accurate picture. And it’s definitely a beautiful one. Just take a look...

…At this Spitzer infrared image of a shock wave in dust around the star Zeta Ophiuchi.

…this Spitzer image of the Helix Nebula, created using infrared data from the telescope and ultraviolet data from the Galaxy Evolution Explorer.

…this image of the “wing” of the Small Magellanic Cloud, created with infrared data from Spitzer and X-ray data from Chandra.

...the below image of the Milky Way’s galactic center, taken with our flying SOFIA telescope. It flies at more than 40,000 feet, putting it above 99% of the  water vapor in Earth's atmosphere-- critical for observing infrared because water vapor blocks infrared light from reaching the ground. This infrared view reveals the ring of gas and dust around a supermassive black hole that can't be seen with visible light. 

…and this Hubble image of the Mystic Mountains in the Carina Nebula.

Learn more about the James Webb Space Telescope HERE, or follow the mission on Facebook, Twitter and Instagram.

Image Credits Eagle Nebula: NASA, ESA/Hubble and the Hubble Heritage Team Hubble Image Processing - Messier 17: NASA/STScI Galaxy M82 Composite Image: NASA, CXC, JHU, D.Strickland, JPL-Caltech, C. Engelbracht (University of Arizona), ESA, and The Hubble Heritage Team (STScI/AURA) Horsehead Nebula: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) Zeta Ophiuchi: NASA/JPL-Caltech Helix Nebula: NASA/JPL-Caltech Wing of the Small Magellanic Cloud X-ray: NASA/CXC/Univ.Potsdam/L.Oskinova et al; Optical: NASA/STScI; Infrared: NASA/JPL-Caltech Milky Way Circumnuclear Ring: NASA/DLR/USRA/DSI/FORCAST Team/ Lau et al. 2013 Mystic Mountains in the Carina Nebula: NASA/ESA/M. Livio & Hubble 20th Anniversary Team (STScI)

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