Why does the Webb telescope take 8 diffracted rays from stars, while Hubble has 4? – Scientific Exploration – cnBeta.COM

In images from the James Webb Space Telescope, the stars appear sharper than before. But what we’re talking about here is not an improvement in image quality, but why do these stars in the picture look like Christmas studs, showing multiple diffracted rays? This is obviously not because of the camera flash.

If you look closely at the stars in the pictures, you will see that there are several types of this “flash”. And you can see that the brighter the stars in the picture tend to emit a zig-zag shape. The brighter the light, the larger and more pronounced this beige shape will be. Dim objects like nebulae or galaxies tend not to see this distortion.

And if you compare the pictures taken by the Hubble Space Telescope, you will see that in the Hubble pictures the stars only emit 4 rays, while the Webb Space Telescope emits 8 rays (2 of them are relatively faint, so it looks like only 6) .

A big reason for this difference is the telescope’s hardware.

Both the Hubble Space Telescope and the James Webb Space Telescope are reflecting telescopes that use mirrors to collect light from the universe. Reflecting telescopes have a large primary mirror that collects light and reflects it back to a smaller secondary mirror. Secondary mirrors on space telescopes help direct light to scientific instruments, turning it into all the images and data we see now.

Both the primary and secondary mirrors affect the light diffracted by the star, but in slightly different ways. Light is diffracted or bent around objects such as the edge of a mirror. So the shape of the mirror itself creates these light diffractions as the light interacts with the edge of the mirror.

Since the Hubble Space Telescope is circular, it does not increase light diffraction, but the Webb Space Telescope uses a hexagonal mirror that produces an image with 6 diffracted light.

Another influence is the secondary mirror. The secondary mirror is smaller than the primary mirror and is kept at a certain distance from the primary mirror by means of struts. On the Webb telescope, the struts are 25 feet long. Light passing through these struts is diffracted, resulting in more diffractions, each perpendicular to the struts themselves.

And Hubble has 4 pillars, which is why you see 4 different diffracted rays. Weber has 3 struts, which cause an additional 6 diffracted rays.

These diffracted rays can cause large distortions. To reduce the amount of light diffracting, NASA’s design overlaps the 4 diffractions caused by the struts and the 4 diffractions caused by the mirrors, which is why the Webb Space Telescope emits 8 rays.