The Webb telescope gives us a new look at a very old world
Lesson summary
Hi there everyone, I’m Jeff and this is Plain English, lesson number 491. JR is the producer and he has uploaded today’s lesson to PlainEnglish.com/491. Now listen, 491 is getting dangerously close to 500. And we have never done anything out of the ordinary for an anniversary or anything like that. But I think we need to celebrate 500 episodes together, so listen until the end and I’ll tell you what we’re planning and—most importantly—how you can be involved in the celebration.
But first: Just seven months after it launched, the James Webb Space Telescope has sent its first images back to Earth. They are just a taste of what’s to come, as the telescope will help scientists peer deep into space—and back in time. In the second half of the lesson, we’ll talk about the phrasal verb “turn over.” And JR has a song of the week. Let’s dive in.
New images from Webb telescope are only the beginning
The James Webb Space Telescope began its journey on Christmas morning 2021 from a launch site in French Guiana, an overseas territory of France in South America. Almost twenty years in the making, the telescope promised to deliver images from deep space that could improve our understanding of the universe, how it was created, how it has developed, and what it might contain today .
The Webb telescope is a joint project, with space agencies from America, Canada, and Europe all collaborating on its design. Over 20,000 engineers, astronomers, technicians, scientists, and other workers have touched the project since it began in 2002. Just over seven months since its launch, the telescope sent its first images back to Earth in the middle of last month.
I’ll tell you more about those images next week. But first, you need to know what’s so special about the Webb telescope.
This telescope is designed to peer into the farthest reaches of the universe using an infrared lens. The Webb telescope will build on discoveries made with the Hubble telescope, which has been in orbit since 1990. The Hubble’s images capture primarily ultraviolet and visible light and they have led to breakthroughs in astronomy. For example, thanks to the Hubble, astronomers now know that the universe is ever-expanding.
The Webb is an improvement in two ways. First, it’s a more powerful lens. The mirror that helps the Hubble take images is 2.5 meters across; the Webb’s will be 6.8 meters across. And the Webb will be able to capture infrared images. The infrared images will let it see through dust and gas that would cloud the images from other telescopes.
The Webb telescope’s mission has four parts:
First, it will investigate the “first light” of the universe. Under the Big Bang Theory, the universe in its early days contained only particles like electrons, protons, and neutrons. There was no light until these particles cooled off and started combining. The first stars came shortly thereafter . The Webb telescope is powerful enough, astronomers think, to study these early forms of light.
Remember, in astronomy, time and distance are related because the universe is ever-expanding. So if something is far away, on the outer edges of the universe, then that means it started a long time ago. The Webb telescope is powerful enough to see light very far away, so far away that it started near the beginning of the universe.
The second part of the mission is to study the composition and arrangement of galaxies. When we think of galaxies today, we think of spirals and ellipses. But those are images from galaxies relatively close to earth. By studying the composition of galaxies farther away, astronomers hope to understand how the earlier ones formed.
There’s a part of the universe about 7,000 light-years from earth called the Eagle Nebula. That part of the universe is known as the “star birthplace.” In the Eagle Nebula, stars form in clouds of gas. But those very clouds make it hard to see how the stars form: the gas obscures the view from telescopes. But the Webb’s infrared telescope can see through that gas to provide a window on how new stars form. That’s the third part of the mission.
And the last part is to look closer to home, but more in-depth. The Kepler Telescope spent over nine years in deep space and its images revealed over 2,600 exoplanets. Those are planets that revolve around other stars. The Webb telescope will be able to take a closer look at those planets, study their atmospheres, and determine whether any of them are likely to support life.
Together, astronomers hope to unravel the mysteries of the universe by studying these four parts of the mission. But before they can do that, they need a reservation.
Having successfully launched the telescope, the project engineers who launched the telescope will turn it over to the Space Telescope Science Institute, a division of NASA based in the American city of Baltimore. That agency gets to determine who can use the telescope and for what reason. There are 6,000 telescope-hours available in the first year…and over 24,000 hours of applications, so a lot of astronomers will be disappointed.
But there is a silver lining . One constraint on a telescope’s total life is its fuel. A telescope needs fuel to make minor adjustments to its positioning, and that takes precious fuel. But the launch was so successful that the Webb saved a lot of fuel on its way up to its current position. That fuel savings means that the Webb might stay in service for 20 years, well above the initial estimate of just ten years.
More on this topic next week
So next week, probably on Thursday, we’ll talk about some of the images that came back. And we’ll also talk about how the Webb telescope was almost canceled back in 2011.
Here’s an interesting fact about the Webb telescope. It’s sitting at something called a Lagrange Point. Anywhere in the universe, large bodies exert gravitational pull on other things nearby. So gravity will move objects out in space, right? So imagine you have two large objects like the sun and the earth both exerting gravitational pull on a small object like a telescope. You can imagine how hard it is to “stand still” somewhere in space if gravity is pulling you in two different directions.
Well whenever there are two large objects, there are five points at which the gravitational pull of the two objects is balanced out. And that’s a great place for a satellite because it won’t need to use as much fuel to make minor corrections to its positioning.
I looked at a diagram of the five Lagrange points between the Earth and the Sun; four make some sort of sense to me and one is a complete mystery.
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