NASA's James Webb first photo released: How to distinguish between stars, galaxies

NASA on Thursday released a stunning photograph of the universe, one of the deepest images of the infinite space ever taken. The photograph that shows a view of stars and galaxies, was released just days ahead of the massive release event of the first "science-quality" images of the universe taken by NASA's flagship James Webb Space Telescope. The high-resolution photos will be released on July 12, for which the American space agency has planned an elaborate event. The teaser" image was not taken by the main massively powerful imaging instruments on board the expensive James Webb Space Telescope  It was taken by the Webb's Fine Guidance Sensor (FGS), whose primary job is to find and lock on to the target. It is very hard for an untrained person to distinguish between the stars and galaxies in the first James Webb Space Telescope ever released. But NASA has explained the photo in detail.

The Fine Guidance Sensor is fully capable of capturing images, but it was designed to facilitate accurate science measurements and imaging with precision pointing, NASA said in a statement. The agency said the images captured by this sensor are almost always discarded as the telescope has limited communications bandwidth. However, during the stability test in May, the scientific team decided it could save the image as there was available data transfer bandwidth.

The image was taken during a thermal stability test in mid-May. NASA said they had not planned to take the image. They were testing how well the telescope can stay locked onto a target. But it could still take the image of a vast area. 

It took 72 exposures over a period of 32 hours of exposure time to produce one of the deepest images of the universe ever taken. The agency, however, said when the sensor's aperture is open, it cannot use color filters, rendering it untenable for scientific exploration.

NASA said the bright stars can be distinguished with their six, long, sharply defined diffraction spikes – an effect due to Webb's six-sided mirror segments. Beyond the stars, galaxies fill nearly the entire background, it added. 

NASA explained that the bright star on the right hand edge is 2MASS 16235798+2826079. Apart from some stars, the faint objects are thousands of galaxies, some even in other universes.

To know how to watch the July 12 event in India, CLICK HERE