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Waiting for Webb

By Caroline Gordon

John Sheff, a facilitator at the McAuliffe Center and NASA JPL Ambassador, presented the lecture, “AstroNights Live,” via Zoom Sept.15.

The lecture concerned the James Webb Space Telescope, which is an orbiting infrared telescope that will build upon the discoveries of the Hubble Space Telescope.

Director of the McAuliffe Center, Irene Porro, introduced Sheff and offered an overview of the Webb telescope.

“I know I’ve said this before, but I need to repeat it every single time. Webb will be the largest, most complex space telescope ever built and launched into space,” she said.

Porro added the launch has been scheduled for Dec.18.

Sheff began by reiterating Porro’s point of the Webb telescope being the “largest and most complex space telescope to ever launch.”

He discussed the science objectives of the Webb telescope. The main goal of the Webb telescope team is to discover more about the universe and its origins.

Sheff said scientists could realize that the “marvellous instrument up in space” can educate us more on not only the origins of the universe, but help us characterize other planets outside of our solar system and the birth of stars.

He described the Webb telescope’s appearance, noting the massive mirrors covering the telescope.

The function of the mirror is to absorb light that comes in from distant objects. As the mirror is

enormous, it can catch more light and photons, allowing the Webb telescope to detect discrete objects, he said.

Additionally, the mirror increases the angular resolution. This allows for the Webb telescope to see more details, when focusing in on an object, he said.

Sheff touched upon how the Webb telescope is infrared.

He said infrared is a region that has been “largely unexplored” with spacecraft, so scientists are expecting “discoveries and surprises.”

Sheff added the Hubble Space Telescope could only see visible light, a bit of ultraviolet light and infrared light.

He discussed the Hubble Ultra Deep Field, a region of space scientists thought was empty – but Hubble proved them incorrect.

Sheff presented an image of the Hubble Ultra Deep Field, noting the vast number of galaxies, which could potentially host billions of stars.

He added scientists know there are more galaxies beyond this, but current technology prevents them from being discovered. However, Sheff said, “Webb will provide us a window into the more distant past, into younger and younger galaxies.”

Sheff discussed the timeline of the Big Bang until now.

He presented images of propolyds captured by Hubble. Propolyds are the “cocoons” of dust and gas in which stars form.

Sheff said we don’t know much about this process, but he believes the Webb telescope will allow us to learn more because of its resolution and ability to see the infrared portion of the electromagnetic spectrum.

In addition to the Webb telescope detecting propolyds, Sheff said it could also detect exoplanets – planets outside of our solar system that orbit a star.

Furthermore, the Webb telescope can discover the elements in an exoplanet’s atmosphere.

Sheff touched upon how chemicals such as carbon dioxide, oxygen and water are associated with life. These life-bearing elements can be detected by the Webb telescope.

The lecture wrapped up with Sheff discussing how the Webb telescope is the beginning of other instruments that will teach us more about the origins of the universe.

“James Webb is not just an isolated end-in-itself type of project. It is a bridge to the future.”


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