By Ron Cowen, Science News
With a smorgasbord of heavenly images and celestial targets to choose from, it wasn’t easy picking a portrait to celebrate the Hubble Space Telescope’s 20th anniversary. But after a debate that began last year, Hubble astronomers finally settled on taking a new, close-up portrait of part of the Carina nebula, a dramatic star-forming region that Hubble first captured in 2007 with a less sophisticated camera.
“We wanted to have an image that will be at least as spectacular as the iconic ‘pillars of creation,’ says Mario Livio of the Space Telescope Science Institute in Baltimore, referring to a widely reproduced 1995 Hubble image of the Eagle Nebula.
“This particular image can arguably be called ‘Eagle Nebula on steroids,’” notes Livio, who led the new observations. The anniversary image “not only shows a region of gas and dust rich in shapes, ionizing radiation, the sculpting effect of radiation and stellar winds, but it also contains two very impressive jets.” NASA released the image April 22 to commemorate the 20th anniversary of Hubble’s launch on April 24, 1990.
The new image highlights the advanced capabilities of the newly installed Wide Field 3 camera, Livio says. “We have also informed the astronomical community that this region will be observed, so that follow-up observations could be made by astronomers interested in star-forming regions.”
Once the images were taken earlier this year, it was up to the institute’s resident image resource expert, Zolt Levay, and his assistant Lisa Frattare to produce the final pictures, with input from Livio. There’s both art and science in assembling those pictures from the raw black-and-white images that Hubble radios to Earth, Levay notes.
He’s acutely aware of criticism that the final product doesn’t resemble what the human eye would see, even if humans had Hubble’s acuity. But the eye, he argues, would be unable to pick out important nuances in an astronomical image without the artificial shading and contrast. In addition, artifacts such as black dots generated by cosmic rays hitting Hubble’s detectors, or repeated halos caused by internal reflections within the telescope, have to be carefully removed, a job that falls to Frattare.
There’s clearly some subjectivity in producing the final image, Levay notes. But in the end, he says, he has to walk a fine line between making the pictures both aesthetically pleasing and astronomically accurate.
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