Sonification of Chandra and Hubble Space Images

We can explore the X-ray universe, a kind of light that no human can ever naturally see.  Since human eyes cannot detect X ray light, we have to translate it from one form into another. And though scientists often prioritize visuals for that kind of data representation, there's no reason why we can't additionally prioritize sound or touch as well, though probably not smell or taste!

Sonification, therefore, is the process that translates data or information into sound, and our latest project brings the high-energy Universe to listeners for the first time. Using NASA’s Chandra X-ray Observatory, the Hubble Space Telescope, and other instruments around the world and in space, we can experience the cosmos through sound. 

Whether it comes from vocal chords in our throats or the surface of the Sun, sound plays a valuable role in our understanding of the world and cosmos around us.

These data sonifications map the data from NASA telescopes into a form that users can hear, embodying the data in a new form without changing the original content.  Listen to three examples:

The Chandra Deep Field Sonification Video:

 
 

The Chandra Deep Field video features a static image of what appear to be colorful stars in a night sky. In fact, these different colored dots are mostly black holes, or galaxies, from a region known as the Chandra Deep Field South. As the video unfolds, a thin, horizontal line in blended reds, yellows, greens, and purples slowly scrolls from the bottom of the image toward the top. When the translucent line encounters a dot, a spike in the line appears, and a sound is played. These tones can be heard in stereo according to their position on the horizontal line. The color of the dot informs the tone. Colors at the red end of the rainbow are heard as low tones. Colors at the purple end of the rainbow are heard as higher tones. The colors are determined by the X-ray frequencies collected by Chandra. Red represents low-energy X-rays, green represents medium-energy X-rays, and blue represents high-energy X-rays. 

The Cat's Eye Sonification Video:

 

The Cat's Eye video features a static image of an ethereal shape surrounded by concentric circles. The shape is the Cat's Eye nebula, a huge cloud of gas and dust blown off of a dying star. The concentric circles are bubbles expelled by the star over time. The dust cloud resembles a translucent pastry pulled to golden yellow points near our upper right and lower left, with a blob of bright purple jelly inside the bulbous pale blue core. The jelly-like center represents X-ray data from Chandra. The outer cloud and translucent circles represent visible light data from the Hubble Space Telescope. As the video unfolds, a white line emanating from the center of the nebula scans the image in a circle, like the second hand on a clock, or the radial arm on a radar screen. The more of the nebula that's in its path, the richer the accompanying sound. Light that is farther from the core has a higher pitch than light that is close to the core. X-rays are represented by a harsher sound, while visible light data sound smoother. The concentric circles create a constant hum interrupted by a few sounds from spokes in the data. Additional videos feature Cat's Eye images and audio from separated X-ray and optical data sets. 

The Messier 51 Video:

 

The Messier 51 video features a static, composite image of the M51 galaxy, better known by its descriptive nickname: the Whirlpool Galaxy. This galaxy resembles a hurricane seen from above, with several veiny red arms that spiral toward a bright white dot at the center. Surrounding the veiny arms are translucent purple clouds and white and purple dots. In the video, a straight white line emanates from the core and scans the image in a circle, like the second hand on a clock, or the radial arm on a radar screen. As the scanning arm interacts with the spiraling red arms, purple clouds, and white dots, notes on the melodic minor scale are played. Different wavelengths of light (infrared, optical, ultraviolet, and X-ray) have been assigned to different frequency ranges. When the spiral arms are prominent, the pitch creeps upward, reaching higher as the arms extend away from the core. The constant low hum is associated with the bright core through which the scanning arm is always passing. The short bursts of sound occur when the scanning arm passes one of the white or purple dots, which are compact sources of light within the galaxy. Additional videos feature the same radial scans for each wavelength frequency range; red for infrared, green for optical, blue for ultraviolet, and purple for X-ray.

For a deeper dive into the sonifications, you can also listen to this NASA Gravity Assist podcast video:

 
 
For a full selection of sonifications, go to our website at http://chandra.si.edu/sound/

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