If you have been keeping a keen eye on developments in space technology over the last few years, you have most likely heard of the James Webb Telescope. This instrument is also commonly referred to as Webb or JWST. In this article, we will explore how the James Webb Telescope works.
This project can potentially “unlock the secrets of the universe”. Due to its complexity, the project was stuck in a tumultuous development cycle for many years. However, the James Webb Telescope has finally launched. Why are so many astronomers and space researchers so excited about this mission?
That’s exactly what we’re going to take a look at today as we break down what exactly the James Webb Telescope is. We will also delve into why it was launched. Finally, we will detail how this infinitely complex machine works.
What Is The James Webb Telescope?
In 1990, NASA launched the Hubble Space Telescope. This wonderful telescope gave scientists a peek into deep space.
After its launch, the planets, stars, and astronomical objects it spotted were analyzed for many years. The project has been a huge success and provided a massive leap forward in our understanding of space and the cosmos. It is still in operation today and will be until sometime in the 2030s.
However, the Hubble Space Telescope has a huge drawback. The instrument is optimized for ultraviolet light, light in the visual range and infrared just beyond the visible range. As a result of red-shift the light from the most distant galaxies changes into near-infrared and progressively into the mid-infrared. To view the more distant galaxies another solution was needed.
To satisfy the need to image longer wavelength light, NASA created a telescope that was even more advanced than Hubble. Unfortunately, it is so complex in design that it took far longer to make than expected and cost a staggering $10 billion.
It seemed like every year, much to the annoyance of space enthusiasts and scientists worldwide, the James Webb Telescope was delayed. However, it was finally launched on Christmas Day 2021.
The telescope currently orbits a point approximately 1 million miles away from the Earth. This point is called the second Lagrange point (or L2), and it is on the opposite side of Earth as the Sun. Lagrange points are areas where the Sun’s and Earth’s gravity interact to produce points where objects can remain in a stable orbit. This reduces the amount of fuel needed to maintain an orbit.
Given JWST’s location, there will be no visits for repairs and/or upgrades like Hubble’s.
The mission of the James Webb Telescope is to find and analyze the first galaxies that formed in the universe and witness stars forming planetary systems. It will also study exoplanets and has already imaged bodies in our solar system.
In this sense, part of its purpose is to go as far back in time as possible. This will allow us to study every phase in the universe’s history, from just after the Big Bang to the eventual formation of our solar system.
The telescope is, therefore, building on what was found by the technologically inferior Hubble Space Telescope. While it has only been in space for an incredibly short time, it is already making discoveries that have challenged our understanding of how the Universe developed.
Another extra goal of the James Webb Telescope is to observe and study the formation of planets and the growth of stars by utilizing infrared technology to see through the masses of dust which often shroud them.
JWST is important, but so is astronomy as a whole. Astronomy is important as it provides us with important technologies and other benefits to society.
How Can The James Webb Telescope Look Back In Time?
The main feature of the telescope that enables it to look back in time is the 21 feet (6.5 meters) wide primary mirror. Rather than a single mirror, it is a mosaic of 18 lightweight beryllium mirrors. These mirrors can be adjusted to perform like a single mirror.
As mentioned earlier, light from the earliest formed galaxies is red-shifted. We will now look at how that occurs.
As light travels from a distant galaxy the space between us and it expands. Not only do the galaxy and us get further apart, but the light itself is also stretched. It is like taking a Slinky (a toy made from a spring) and pulling the two ends apart. If you look carefully, the links become further apart. This is exactly what occurs with light. The light waves become longer. Longer wavelength light becomes redder and redder. With enough stretching, they move from visible light to near-infrared to mid-infrared.
Remember that the objects we observe now are no longer in the same place as when the light was emitted. While the light has been traveling and stretched the object that emitted it has moved farther from us.
JWST is optimized to observe light that is no longer visible. It searches for light that has been red-shifted into the infrared wavelengths. We need space-based telescopes for this purpose, as the atmosphere blocks them.
The primary mirror of the telescope will intercept infrared light traveling through space. It will reflect it onto the smaller secondary mirror which guides the light towards the scientific instruments where it can be recorded.
If you ever look at a picture of the James Webb Telescope, you’ll also notice a large slightly curved surface below the bottom of the mirrors.
This is simply a shield which simply protects the mirrors from being affected by the rays and temperature of the sun.
Webb then sends the information back to Earth using a high-frequency radio transmitter. The information is relayed directly to the Webb Science and Operation Center in Baltimore.
James Webb Instruments
You may think that JWST records images using a single camera. However, it uses four different imaging instruments located behind the mirror array.
The different instruments are optimized to perform a particular job. One important aspect of this is that they are optimized to be sensitive to a narrow part of the spectrum.
We will have a quick look at each of JWST’s four instruments
NIRCam
NIRCam is an acronym for Near-Infrared Camera and is the main JWST instrument. Its purpose is to study galaxy formation and exoplanets. As the name suggests, it is sensitive to near-infrared radiation with a wavelength of 0.6 to 5 microns.
NIRSpec
We need to use spectrography to understand objects’ composition, temperature and mass. This is the function of NIRSpec. This spectrograph operates in the same wavelengths as NIRCam. It can analyse up to 100 objects simultaneously.
MIRI
The Mid-Infrared Instrument (MIRI) has both a camera and a spectrograph. It operates at longer wavelengths as the previous two instruments. It is sensitive to wavelengths of between 5 and 28 microns. At these wavelengths, we can study the light from galaxies that have been red-shifted into the mid-infrared. It can also be used to find planets around stars, dust around planets, and protoplanetary disks. Closer to home it can be used to observe comets and asteroids.
FGS/NIRISS
FGS/NIRISS is a combination of two devices. The Fine Guidance Sensor (FGS) accurately points JWST to where it needs to. The Near Infrared Imager and Slitless Spectrograph (NIRISS) operates at the same wavelengths as NIRCam and NIRSpec. Its purpose is to study the universe’s earliest light and exoplanets.
What Has The James Webb Telescope Found So Far?
Although the Webb telescope has only been probing deep space for a short time, it has already provided scientists with a few incredible revelations.
Here are some of the biggest discoveries that the James Webb Telescope has made so far:
Galaxies and star formations – Webb was able to see through the dust and gas surrounding the center of a galaxy found within the Pegasus constellation. This has given scientists an incredibly high-detailed and unprecedented look at how galaxies interact with one another to trigger star formations.
The Cosmic Cliffs – Webb identified the earliest phases of star formations within the Carina Nebula which had never been seen before. Scientists are studying the gas and dust that made these newly formed stars. They hope Webb can locate other rare star-forming regions that we never knew existed. The image from this program is above.
JADES-GS-z14-0 – This is the name of the farthest and oldest galaxy that Webb has observed (Space). It formed just 300 million years after the Big Bang. Considering the universe’s expansion, the distance to this galaxy is now 33.6 billion light-years. This makes this one of the biggest discoveries in the history of astronomy to date.
Summary
The James Webb Telescope is the most magnificent and technologically advanced resource for understanding the universe’s origins. While we can expect many more incredible revelations and discoveries in the next few years, it has already challenged of views on the universe, along with the stars, planets, and galaxies that occupy it.
Hi, my name is Jason Anderson, and I am a Physics Professor. Ever since I was a kid, I’ve been fascinated with space, the universe, the moon, you name it. I spent hours and hours at the planetarium close to my hometown, wondering what else could be out in the universe.
Since then, I’ve been an avid stargazer and astronomer, and love nothing more than spending my time charting stars, observing planets, and finding constellations.
This is why I decided to start Telescope Guru. I only wish to share this fun pastime with the world. With this site, I hope to answer all of your questions relating to astronomy, telescopes, and stargazing.
