NASA’s James Webb Space Telescope (JWST) has produced the “deepest and sharpest infrared image of the distant universe to date”, according to a press release yesterday (11 July 2022) – what is the resolution of the image?

In the release, NASA describes the image as “overflowing with detail”.

It’s a composite, and among the telescope’s first full-colour images.

Those seeing it for the first time have reported wanting to “stare at [the image] for a while” while wearing a virtual reality (VR) helmet – but what do we know about its angular resolution and other technical specifications?

Karl Merton Ferron/Baltimore Sun/Tribune News Service via Getty Images

What is the resolution of JWST’s composite image?

You can download the first infrared image from NASA’s James Webb Space Telescope (JWST) in three levels of detail, or resolution.

The full resolution image is 4,537 pixels by 4,630, meaning JWST’s first publicly viewable infrared image is 21 million pixels, or 21MP.

Translated into digital format, the file is 28.51 megabytes (MB). You can download the full resolution image here as a PNG. Find it below.

A low resolution version of JWST's first full-colour composite image release
Source: NASA/James Webb Space Telescope

An alternative, at a lower resolution, is also available here. The file size is 5.52 MB.

How does the JWST compare to the Hubble Space Telescope in terms of image resolution?

For a direct side-by-side comparison of images captured and composed by JWST and Hubble, see below.

For both images overlaid and viewable in GIF format, click here.

The image is brighter, sharper and clearer. The difference in detail, writes PetaPixel, is “astounding”.

Both capture the same area of the sky. Hubble imaged SMACS 0723 – the name of a particular galaxy cluster in the image – before. Find a suppository of its composites in the Hubble Legacy Archive here.

With regard to the relative resolutions of the Hubble telescope’s imaging capacity and that of the JWST, however, the difference takes a bit of explaining.

1990 - This color image of Saturn was taken with the Hubble Space Telescope's (HST's) Wide Field Camera (WFC) at 3:25 am EDT, August 26, 1990, when the planet was at a distance of 2.39 million km (360 million miles) from Earth.
Photo by: HUM Images/Universal Images Group via Getty Images

JWST vs Hubble in terms of angular resolution

Angular resolution is the term astronomers use to describe an image’s “sharpness”. Two factors affect how sharp an image is, according to NASA’s webpage on JWST FAQ.

First is the diameter of the mirror; second is the wavelength being observed. Hubble sees shorter wavelengths of light than the JWST (they call it simply “Webb”), but the JWST has a mirror 2.75 times larger in diameter than Hubble. 

That means Hubble has roughly the same angular resolution at 700 nm that the JWST does at 2,000 nm (or 2 microns). Hubble, therefore, sees light ranging from 200 nm to 2.4 microns, while the JWST sees light that ranges from 600 nm to 28 microns – a much larger range.

In other words, the JWST has better infrared capability than Hubble. It sees deeper into the infrared. This, plus its larger mirror and new detectors, means the JWST is able to capture superior images despite what might seem like negligible differences in terms of angular resolution.

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When will NASA release the full suite of its JWST images?

The image NASA and the JWST released today is among the telescope’s first full-colour images.

NASA will release the full suite on Tuesday, 12 July 2022, beginning at 10:30am EDT.

Tune into the agency’s live TV broadcast to be among the first to see them. For more information on how to watch it, click here.

The launch of the James Webb Space Telescope took place on 25 December 2021. It should undertake 20 years of imaging before retirement. The Hubble Space Telescope, meanwhile, has been going for 32 years.

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