JAMES WEBB SPACE TELESCOPE (JWST)
1. Context
NASA’s James Webb Space Telescope (JWST) has spotted the earliest-known galaxy, one that is surprisingly bright and big considering it formed during the universe’s infancy — at only 2% its current age. The discovery was made by an international team of astronomers, who used JWST to observe galaxies as part of the JWST Advanced Deep Extragalactic Survey (JADES) program.
2. What do we know about the galaxy?
This galaxy, called JADES-GS-z14-0, measures about 1,700-light years across. A light year is the distance light travels in a year, which is 9.5 trillion km. The galaxy has a mass equivalent to 500 million stars the size of our Sun and is rapidly forming new stars — about 20 every year.
Until now, the earliest-known galaxy dated to about 320 million years after the Big Bang, as announced by the JADES team last year.
“It is significantly larger than other galaxies that the JADES team has measured at these distances, and it’s going to be challenging to understand just how something this large could form in only a few hundred million years,” Hainline said.
Source: BBC
3. Why is the galaxy so bright?
Three main hypotheses have been proposed to explain the brightness of early galaxies. The first suggested that supermassive black holes in these galaxies were consuming large amounts of material. However, this idea seems unlikely based on new findings, as the observed light is spread over a larger area than would be expected from black holes alone.
Astrophysicist and study co-author Francesco D’Eugenio from the Kavli Institute for Cosmology at the University of Cambridge noted that it is still uncertain whether the other hypotheses—that these galaxies contain more stars than anticipated or that the stars are inherently brighter than those found today—will be supported by further research.
4. Features of James Webb Space Telescope
The James Webb Space Telescope (JWST) boasts several advanced features that make it a groundbreaking instrument for astronomical observations:
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Large Primary Mirror:
- The JWST's primary mirror is larger than the Hubble Space Telescope's mirror. This large mirror allows for greater light-gathering capability, enabling the telescope to observe faint and distant objects.
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Infrared Observations:
- JWST is primarily an infrared telescope, designed to observe the universe in the near-infrared (0.6 to 5 micrometers) and mid-infrared (5 to 28.5 micrometers) wavelengths. This capability is crucial for studying the early universe, star formation, and the atmospheres of exoplanets.
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Advanced Instruments:
- The telescope is equipped with four main scientific instruments:
- NIRCam (Near-Infrared Camera): Captures images in near-infrared light.
- NIRSpec (Near-Infrared Spectrograph): Performs spectroscopy in the near-infrared range.
- MIRI (Mid-Infrared Instrument): Observes in the mid-infrared spectrum, providing both imaging and spectroscopy.
- FGS/NIRISS (Fine Guidance Sensor and Near-Infrared Imager and Slitless Spectrograph): Aids in precise pointing and provides additional imaging and spectroscopic capabilities.
- The telescope is equipped with four main scientific instruments:
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Sunshield:
- JWST features a large, multi-layered sunshield the size of a tennis court. This sunshield protects the telescope's instruments from the heat and light of the Sun, Earth, and Moon, keeping them at extremely low temperatures necessary for infrared observations.
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Location:
- The telescope orbits at the second Lagrange point (L2), approximately 1.5 million kilometers (about 1 million miles) from Earth. This stable location allows for uninterrupted observations and a clear view of the cosmos without the interference of Earth's atmosphere.
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Deployment and Folding Design:
- Due to its large size, JWST was designed to be folded to fit into the rocket for launch. It then undergoes a complex unfolding process in space, including the deployment of its mirror and sunshield.
These features collectively make JWST a powerful tool for advancing our understanding of the universe, from the earliest galaxies to the potential for life on other planets.
Source: BBC
5. Way Forward
JWST, which by peering across vast cosmic distances is looking way back in time, observed the galaxy as it existed about 290 million years after the Big Bang event that initiated the universe roughly 13.8 billion years ago, the researchers said. This period spanning the universe’s first few hundred million years is called cosmic dawn
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Previous Year Questions
Mains PYQ:
Q. Launched on 25th December, 2021, James Webb Space Telescope has been much in the news since then. What are its unique features which make it superior to its predecessor Space Telescopes? What are the key goals of this mission? What potential benefits does it hold for the human race? (2022)
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Source: Indian Express
