The stunning first images from the James Webb Space Telescope provide the deepest and clearest look yet at outer space. Lisa Grossman reported in “Postcards from a new space telescope” (SN: 8/13/22, pg. 30).
JWST observes space using infrared, a form of light that is not visible to the human eye. To visualize the images, scientists color them. Reader John Dohrman I was wondering how that coloring is done.
The JWST images are colorized by Senior Data Imaging Developer Joseph DePasquale and Science Imaging Developer Alyssa Pagan, both of the Space Telescope Science Institute in Baltimore. gross man He says. His basic rule of thumb is to paint the images using wavelengths of light as a guide. Light emitted at the longer wavelength in an image is assigned the color red, and the shorter one is blue, she says. The intermediate wavelengths are assigned a spectrum of greens and yellows (SN: 03/17/18, pg. 4). But there are also other considerations, like data on the chemical compositions of the things in the image. How to color those elements can be more of an art than a science, gross man He says. “There is also a subjective art.”
Reader Stu Kantor asked why some stars in the JWST images appear to have eight peaks, six large and two smaller (see “Out of this world,” below).
Those are called diffraction peaks, gross man he says, and they are an artifact of the telescope’s optical setup. JWST has two mirrors: a hexagonal primary mirror and a smaller secondary mirror that faces the primary mirror and is supported by three support beams. When it reaches the telescope, the light is bent at the two edges of each of the secondary mirror mounts, producing six diffraction peaks. The six edges of the primary mirror also create six peaks. The scientists designed the telescope so that four of the peaks from the secondary supports overlapped with four of the peaks from the primary mirror. gross man says, so even though there are 12 peaks, we only see eight.
Diffraction spikes are not unique to JWST. “Hubble Space Telescope images also have these, but they only have four.” gross man He says. “The eight dots are a distinctive feature of JWST, like an artist’s signature.”
In the nose
Scientists discovered a neural link in the dog brain that connects the olfactory system with vision, which may help explain why humanity’s best friend is a good sniffer. laura sanders reported in “New nose-brain link identified in dogs” (SN: 8/13/22, pg. 9).
The story inspired several readers to reflect on the behavior of their own furry friends.
“Now I know why my German Shepherd couldn’t play the simpler version of the shell game,” edward hughes wrote. “Using a small piece of dog food and two Dixie cups…a change in the location of the cup that concealed the dog food completely confused her. I could see her eyes follow the cup, but she never took the cup with the dog food. She had pre-located it with her nose, and everything her eyes detected was completely ignored.”
Reader Roy R. Ferguson shared his fascination with the scent abilities of dogs, having worked with the animals in search and rescue efforts for the past 20 years with his wife.
“We’ve learned to let the K-9s do their jobs with as little supervision as possible.” Ferguson wrote. “They constantly make decisions that seem unusual at the time but make sense once the full story is known.”
“Our K-9s have located blood droplets in light rain and human decomposition on multiple vehicles. The live finds include a man who wandered more than 10 miles after a head injury and a 6-year-old boy who had been out all night… The boy’s find was notable due to the large amount of contamination by odors in the area”, Ferguson additional.
“We have no idea how these incredible creatures do such amazing feats. They work their hearts out for nothing more than praise and a toy reward.” Ferguson wrote. “She has come up with [us] that we are here to support, promote and work on the radio. In return, they make us look like we know what we’re doing.”