Can you quantify how much better JWST is compared to Hubble? For instance, from what distance can each "see" (differentiate) a sun-like star?

Maybe there are other measures.

  • $\begingroup$ Potentially helpful link: jwst.nasa.gov/content/about/faqs/faq.html#sharp $\endgroup$
    – Topcode
    Jul 12, 2022 at 6:27
  • $\begingroup$ Hubble and JWST are designed for different wavelengths, Hubble for visible light, JWST for red to mid IR. So you may compare resolution and sensitivity only for red light detectable by both telescopes. $\endgroup$
    – Uwe
    Jul 12, 2022 at 11:24
  • $\begingroup$ I think, the images just released at the press conference and at nasa.gov/webbfirstimages (where similar hubble images are referenced) gives a very good visual indication. $\endgroup$
    – TrySCE2AUX
    Jul 14, 2022 at 5:31

1 Answer 1


Due to the redshift very far stars and galaxies are not detectable within the range of visible light but as infrared. The JWST is built for longer wavelengths than the Hubble so it can "look" farther.

Hubble could not "look" farther than about 400 million years after the big-bang, but the JWST may look to about only 180 million years after the big-bang.

You asked for distances and not for the "age" of light. I am sorry, it is not possible to calculate a well defined distance from the age of light.

  • $\begingroup$ This is a really good point. Still, I think my example is about something a bit different. Namely, I asked about diffraction limit (this is the word). But it is true, that in different distances, the red shift will cause it to be infrarred or near. And yet, I think there might be such limit for the distance, if we consider both the redshift and we assume main class star of sun's radius. Let me know if I am wrong. It would be interesting to know this, even ignoring the red shift. Though, not practical $\endgroup$ Jul 13, 2022 at 22:47
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    $\begingroup$ @user2679290 The angular resolution of JWST's NIRCam is 0.07 arcsec at 2 microns. That corresponds to the angular diameter of the Sun at a distance of ~0.4334 light-years. $\endgroup$
    – PM 2Ring
    Jul 15, 2022 at 1:33
  • $\begingroup$ In visible light (at wavelengths near 500 nm) the combination of the Hubble telescope plus its highest resolution cameras achieve an angular resolution of about 0.04 arc seconds. $\endgroup$ Jul 15, 2022 at 21:37

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