Griggs, in
“Why stars look spiky in images from the James Webb Space Telescope”
(Griggs,2022) explains the technology behind the James Webb Space Telescope
(JWST) and how it compares to its predecessor, the Hubble Space Telescope with
regards to the number of diffraction spikes. The article was published in the
American technology news website known as The Verge on the 16th of
July 2022.
The JWST is
the latest, most powerful telescope, cruising millions of miles away from
earth, developed by NASA. It observes our galaxy by using infrared light and
hopes to see the past and give information about how the galaxy has changed
from billions of years ago until today. It was launched on the 25th
of December 2021 in Guiana Space Center, Europe.
The article
begins by giving a very brief explanation on the working principal of a
telescope. It then discusses the differences between the Hubble Telescope and
the JWST. The reason why the JWST is becoming popular is because of its improved
design and technology. The JWST is a revolutionary telescope because it utilizes
hexagonal mirrors and multiple camera instruments which is able to gather and study
new information about our solar system that other telescopes are not capable of
doing so due to their lack of technology.
There are several
mentioned examples in the article explaining the engineering and technology
used by the JWST.
The JWST
uses hexagonal mirrors primarily instead of a single round mirror used in the
Hubble Telescope. This results in an image with six diffractions. The purpose
of primary mirrors in a reflective telescope is to guide the light into the
secondary mirror. Griggs states that “The shape of the primary mirror, in
particular the number of edges it has, determines the mirror’s diffraction
pattern” (Griggs, 2022).
The JWST utilizes
multiple camera instruments to view the solar system. The NIRCam (near-infrared
light) is the telescope’s main imager. It shows more prominent diffraction
spikes because stars are very bright at those wavelengths (0.6 to 5 microns).
“NIRCam will detect light from: the earliest stars and galaxies, in the process
of formation, the population of stars in nearby galaxies, as well as young
stars in the Milky Way and Kuiper Belt objects” (NASA, 2021). The NIRSpec (Near
InfraRed Spectograph) is used to distribute the amount light from a certain
target into a spectrum. “Analyzing the spectrum of an object can tell us about
its physical properties, including temperature, mass and chemical composition” (NASA,
2021). There is also a Mid-Infrared Instrument (MIRI) that consists a camera
and a spectrograph. Its main role is to view the light in the mid-infrared area
of the electromagnetic spectrum. The wavelength of the MIRI has a range of 5 to
28 microns. In this range, it gives us a visual of the solar system longer than
our eyes can ever see.
The reason
behind the making of the JWST is for astronomers to discover further into the
galaxies than ever before. The aim is to discover what lies after the Big Bang.
Scientist have spent over 30 years developing the JWST, costing approximately
$10 billion USD. Compared to Hubble, the JWST is bigger and better and can see
much further into the universe. For example, the JWST can look further because
the mirrors collect much more light energy due to its 6.5-meter diameter mirror
while the Hubble’s primary mirror is only 2.5 meters in diameter (CNET, 2022). This
allows scientists to discover new galaxies and learn about the beginnings of
time.
References
1) Griggs, M. (2022). Why stars look spiky in images
from the James Webb Space Telescope. Retrieved 17 September 2022, from https://www.theverge.com/23220109/james-webb-space-telescope-stars-diffraction-spike
2) Key Facts - Webb/NASA. (2022). Retrieved 17
September 2022, from https://jwst.nasa.gov/content/about/faqs/facts.html
Reilly, C. (2022). James Webb Space Telescope: NASA's First Images Explained. Retrieved 24 September 2022, from https://www.youtube.com/watch?v=XvfuxtVr7JY&t=1s
Edited: 29 September 2022
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