• Post category:Space Exploration
  • Reading time:7 mins read

The last few days were great for science. We got some very beautiful, information-packed images from deep space. All thanks to the James Webb Space Telescope.

Webb's First Deep Field Unveiled (NIRCam Image) Photo Credits: NASA
Webb’s First Deep Field Unveiled (NIRCam Image) Photo Credits: NASA

Not seen the images yet?

The image you see above is at a distance of 4.24 billion light years away from us! And the age of our planet is estimated to be 4.5 Billion years!
If you have not seen the images yet, please stop everything and go to this official link for all the recent images. It is a MUST WATCH!
After you have zoomed in and out on all, come back here to understand three important aspects of these images. 

An enormous mosaic of Stephan’s Quintet is the largest image to date from NASA’s James Webb Space Telescope, covering about one-fifth of the Moon’s diameter. Photo Credits: NASA
An enormous mosaic of Stephan’s Quintet is the largest image to date from NASA’s James Webb Space Telescope, covering about one-fifth of the Moon’s diameter. Photo Credits: NASA

How do these images get colors?

James Webb is an infrared telescope. The images from JWST like the one of the Carina nebula (shown above) and the deep field image are composed of data from the infrared spectrum, which has a longer wavelength than visible light. JWST used its infrared cameras to gather a number of grayscale “brightness images” to create the photos that are currently being shared.
Different infrared light wavelengths were each collected by one of six filters. Each filter on Earth was given a color. The filters that captured the longest and shortest wavelengths were red and blue, respectively, with the other colors falling in between. These photos were combined to create a composite image that includes every color present in the current photos.

So next time you hear someone saying the images are “edited”, remind them that the correct term is “processed”. No information is removed or added or altered from the actual photos.

 You will notice curved light streaks in the image. Read below to understand the reason.
You will notice curved light streaks in the image. Read below to understand the reason.

The curved light streaks?

This is the result of an effect known as gravitational lensing. The powerful gravitational field of a galaxy cluster can bend the light rays from more distant galaxies behind it, just as a magnifying glass bends and warps images. 

A simpler (and more accurate) way of understanding is that instead of the light bending, the universe is bending around the massive object, which light passes near, so instead of the light being bent, the reality is. As an analogy imagine looking at a glass of water with a straw in it. From the side angle, you’ll see that the straw looks broken. We know that isn’t true, just an optical illusion.
If you look top down into the straw, you would see the straw is straight, unbroken. In the view of the light, it doesn’t bend at all. It goes in a straight line, but we are seeing it “bent” simply because it is passing through an area of space that is being warped. It’s not the light that is being pulled, but the very fabric of time and space which is being pulled.

This effect is known as gravitational lensing, and the amount of bending is one of the predictions of Albert Einstein’s general theory of relativity.

The 8 Spiked Stars in JWST images

The 8 Spike Stars

These are diffraction spikes. This happens because of how the telescope is constructed and some unavoidable elements. The sharp edges of the telescope’s primary mirror and the struts supporting the secondary mirror create these patterns as the light bends around them.

The primary, secondary mirror and struts in JWST
The primary, secondary mirror and struts in JWST

JWST struts and the shape of the mirror are designed intelligently to overlap some of those spikes. The combined effect results in the 8 spike star.

Explanation of Spike formation. The individual contribution of primary mirror and struts

Hubble vs JWST

A comparison of spikes from Hubble and JWST. Source: NASA
A comparison of spikes from Hubble and JWST. Source: NASA


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