Space is massive, and in many areas, amazingly beautiful. We are fortunate to live in a time when humans are able to see at least a small portion of the beauty that is out there, and that is in no small part because of telescopes like the Hubble Space Telescope and the James Webb Space Telescope.

These telescopes are out in space themselves, so when using them, there is no distortion from the Earth’s atmosphere. They were designed to be very powerful as well, letting them look across vast distances and generate images from places in the universe that we would otherwise not even know existed.

When looking at the pictures that come from these telescopes, you may notice that they have an almost cinematic quality to them.

Specifically, the brightest points have what are known as diffraction spikes, which are points of light coming off of them. With the James Webb Space Telescope, there are eight spikes (six large, two small). The Hubble, on the other hand, only has four.

So what are these? Does NASA add them in during the processing of the images to make them more dramatic?

No.

The reason they are there is actually due to the way these telescopes are made.

Diffraction is what when a wave of light passes by the edge of another object, which causes the light to bend. In these telescopes, the light is bent around the struts that hold the various mirrors that gather and focus the light.

Depending on how many struts there are, and how many times the light is diffracted, there will be more or fewer spikes of light, and they can be larger or smaller.

The James Webb Space Telescope has three struts holding its secondary mirror in place, which produces the six spikes. Four of those struts overlap with the telescope’s main mirror, which adds two more spikes.

While these spikes of light add a dramatic flare to the images, they are actually not wanted because they can hide other objects that would otherwise show up.

Future telescopes, including the Giant Magellan Telescope that is being developed, will hopefully be able to eliminate these diffraction points thanks to precision configurations that dramatically reduce or eliminate blocked light from support struts.

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