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 5-½ 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.
Carina Nebula: ESO/T. Preibisch
Monkey Head Nebula: NASA, ESA, the Hubble Heritage Team (STScI/AURA), and J. Hester
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