Have you ever scrolled through Instagram and marveled at a breathtaking photo of a distant nebula or galaxy? What does it takes to capture such celestial beauty?
As it turns out, the satellites and telescopes capturing these deep-space marvels only take pictures in black and white.
So what gives? How do you capture a full-color image when your recording medium can only see in black and white?
NHPR's Patrick McNameeKing sat down Nicole Gugliucci, an astrophysicist from Saint Anselm College, to learn how we get those stunning, colorful images of the cosmos.
The Power of the CCD
Almost all modern digital cameras — including the massive ones mounted on space telescopes — rely on a technology called a Charge-Coupled Device (CCD). Astronomy was an early adopter of CCD technology because it is vastly more efficient at capturing faint light than old-school photographic film.
However, according to Gugliucci, there's a catch: CCDs detect photons (little particles of light) and convert them into an electronic signal. They are incredibly good at measuring how much light is hitting them, "but they don't tell you what color it is."
Red, Green, and Blue: Building the Spectrum
To bring color to the cosmos, scientists use a method similar to how early color photography worked. They place high-tech color filters — essentially precise pieces of colored glass or film — in front of the camera sensor.
By layering these individual images together using digital software, scientists can recreate a full, vibrant color image that mirrors what the human eye would see.
This process isn't just limited to the visible light spectrum. Space is filled with light that human eyes can't detect, such as ultraviolet (UV) and infrared (IR).
Telescopes equipped with UV and infrared filters capture these hidden wavelengths. Scientists then assign visible colors (like red, green, or blue) to these invisible wavelengths so our eyes can process the data.
Have a question about the night sky or space exploration? Send an email to the team at cosmic@nhpr.org.
