Summary/Reader Response: Draft 3

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  Griggs’s article “Why stars look spiky in images from the James Webb Space Telescope” (Griggs, 2022) explains how the stars appear clearer than ever in the new images captured by the James Webb Space Telescope. The article explains how the JWST differs from its predecessor, the Hubble telescope with reference to the number of diffraction each telescope produces.  With the aim to take distinct images of the stars, The U.S. National Aeronautics and Space Administration has developed a telescope equipped with “hexagonal mirrors that result in an image with six diffraction spikes”. Taking a closer look, it is described that all of the bright objects in the JWST photos have the same eight-pointed pattern, making them look like Christmas ornaments looking spikes.  Griggs reports that the near-infrared lights gathered by the Near-Infrared Camera (NIRCam) enhance the diffraction spikes of the stars. The NIRCam is one of the developments of JWST  in order for the telescope to deliver clear images of the stars. Moreover, the telescope is also equipped with a Mid-Infrared Instrument (MIRI) that picks up mid-infrared light instead. Griggs also states that though MIRI is engineered to pick up diffraction spikes around the stars, "they are fainter and smaller" compared to the NIRCam.

On the other hand, the JWST's secondary mirror, supported by three struts, produced six additional spikes, resulting in significant distortion. Griggs addresses that JWST alone has observed this particular diffraction spike pattern. Photos from the new telescope can be compared to images from its predecessor, and you'll see that JWST has eight diffraction spikes compared to Hubble's four (Griggs, 2022). With JWST's advanced developments, scientists are able to widen their knowledge using greater coverage of wavelengths and increased sensitivity. JWST’S advanced features and technology will allow it to discover younger galaxies, capture clearer images and require lesser maintenance.

The scope and detail in the first photos from the JWST have far surpassed those of the rivals (Bower, 2022). Why some might downplay the significance of the Hubble telescope is understandable. It is crucial to keep in mind that the missions of the two telescopes differ when comparing two. Multiple articles have reported on the engineering and technology of JWST that has contributed to its successful mission. JWST’s primary mirror is a 25-square-metre made of 18 hexagonal mirror segments, as a result, an image with six diffraction spikes is produced. Around surfaces like the edges of mirrors, light diffracts or bends. Light interacting with the mirror's edges can cause these light spikes depending on the mirror's shape. The mirror in Hubble's example was circular, thus it didn't increase the spikiness. However, the JWST telescope contains hexagonal mirrors, which provide a picture with six diffraction spikes (Griggs, 2022). Due to its large size, it was a challenge to ensure that the 25 feet long mirror was lightweight, whilst being “distortion-free for excellent image quality” (NASA, n.d.)

Aside from its reflective mirror, the cameras in JWST played a huge role in the success of its mission. JWST is equipped with NIRCam and MIRI instruments, which have 2 different purposes to discover deep into our galaxies. Webb's main imager, the Near Infrared Camera (NIRCam), will be able to see infrared light with a wavelength range of 0.6 to 5 microns. It will be able to pick up light from young stars in the Milky Way and Kuiper Belt objects, as well as the first stars and galaxies that are forming (NASA, 2020). 

On the other hand, in order to perceive light in the mid-infrared area of the electromagnetic spectrum, which has wavelengths longer than those seen by human eyes, the Mid-Infrared Instrument (MIRI) has both a camera and a spectrograph. The 5 to 28-micron wavelength range is covered by MIRI. Its sophisticated detectors will let it view objects in the Kuiper Belt as well as the redshifted light of far-off galaxies, freshly forming stars and faintly detectable comets. Wide-field, broadband imaging from  MIRI's camera will maintain the breathtaking astrophotography that has earned Hubble such widespread acclaim (NASA, 2020). 

In contrast to the JWST requiring a lesser amount of servicing, it being distant from earth’s orbit will affect the longevity of the space telescope. It is reported that the Hubble’s reason for the long lifetime is probably that it can be serviced while in orbit and is safer because it is closer to earth (Bower, 2022). However, with JWST’s advanced technology and features, it is assumed to have a long lifespan.

In conclusion, the JWST improved features and function were a success for astronomers to possibly go back in time and discover the Big Bang. The near-infrared instrument and primary mirror engineered to capture diffraction spikes have enabled JWST to detect lightwaves from early stars and galaxies while capturing clear images of them. The launch of JWST gave astronomers one step closer to learning about our universe in the past.



References

Bower, J. (2022, August 5). 9 Differences Between The Hubble and James Webb Telescopes. Screen Rant. Retrieved September 25, 2022, from https://screenrant.com/the-hubble-james-webb-telescopes-major-differences/

Griggs, M. B. (2022, July 15). Why stars look spiky in images from the James Webb Space Telescope. The Verge. Retrieved September 17, 2022, from https://www.theverge.com/23220109/james-webb-space-telescope-stars-diffraction-spike

In Depth | James Webb Space Telescope – NASA Solar System Exploration. (2022, July 12). NASA Solar System Exploration. Retrieved September 27, 2022, from https://solarsystem.nasa.gov/missions/james-webb-space-telescope/in-depth/

NASA. (n.d.). Technologies for the James Webb Space Telescope. James Webb Space Telescope. Retrieved September 28, 2022, from https://www.webb.nasa.gov/resources/2008techflyer.pdf

NASA. (2020). Mid-Infrared Instrument (MIRI) Instrument Webb/NASA. James Webb Space Telescope. Retrieved September 29, 2022, from https://webb.nasa.gov/content/observatory/instruments/miri.html

NASA. (2020). Near Infrared Camera (NIRCam) Instrument Webb/NASA. James Webb Space Telescope. Retrieved September 29, 2022, from https://www.jwst.nasa.gov/content/observatory/instruments/nircam.html

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