Kelly Lepo (@kellylepo@astrodon.social)

The most frequently asked question that I get about #JWST images is: "Why do the stars look like that?". In other words: why are the stars "spikey"?

The answer has to do with both the wave nature of light, the shape of the telescope's primary mirror, and the position of the struts that hold up the secondary mirror.

The full infographic on JWST diffraction spikes can be downloaded here: https://webbtelescope.org/contents/media/images/01G529MX46J7AFK61GAMSHKSSN

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#thread #astrodon #astronomy

At the bottom left of this vertical image are the thickest regions of brown and rusty red gas and dust.
There are many layers of semi-transparent gas and dust overlaying one another. A peak rises about a
third of the way from the bottom, and becomes far darker brown with two bright red areas toward the
tip. The light brown dust becomes more diaphanous about halfway up the screen. There’s a slight gap in
the dust, which allows the blue background to come into view clearly. About 60% of the background in
this image is set in shades of blue and littered with tiny yellow and blue stars. The brown pillars
continue, taking the shape of a shoulder at the base, with three prominent columns rising out toward
the upper right. The top left pillar is the largest and widest. The peaks of the second and third pillars are
set off in darker shades of brown and have red outlines.

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