Space Isn’t As Dark As We Know It

For decades, astronomers have been posing the question of whether space is truly as dark as it appears. NASA's New Horizons space mission may have provided an answer. After exploring Pluto, the spacecraft continued its journey and is now billions of miles away from Earth, far from any light pollution caused by sources such as the sun and dust particles around our planet. Scientists utilized the spacecraft's simple camera to capture images of what appeared to be an unremarkable, blank space devoid of bright stars or any other objects that could scatter light back into the camera. These images were then processed to eliminate all known sources of visible light. Once the light from stars and scattered light from the Milky Way had been removed, only light from beyond our own galaxy remained. However, the surprising discovery was that there was still a significant amount of unexplained light, equivalent to all the light emanating from known galaxies. This suggests that there is just as much light outside of galaxies as there is inside them. The origin of this light remains a mystery, but it could be attributed to undiscovered sources such as faint dwarf galaxies or unknown phenomena in the universe. Alternatively, it may be associated with dark matter, which is still not fully understood by scientists. This groundbreaking research indicates that space is not as dark as previously believed. If we were to remove all the light from stars and galaxies and add in some gas and dust clouds, the resulting color would be beige. This raises the question of whether we still require the sun if space is colorful. The answer is yes. The colors of space are a result of the interactions of light with different celestial objects, such as stars, galaxies, and gas clouds. While these colors are fascinating to observe, they do not provide the energy necessary for life on Earth to survive. Therefore, the color of the sky in space will not be visible to us.

In the 1990s, NASA launched a highly intricate space telescope into Earth's Low Orbit, which is the altitude between the Earth's surface and 2,000 kilometers (1,200 mi). As it is situated outside our atmosphere, the telescope can observe astronomical objects across a wide range of the electromagnetic spectrum, from ultraviolet light to visible and near-infrared wavelengths. Additionally, the telescope can detect faint objects in close proximity to bright ones.

The telescope's angular resolution is 0.05 arc seconds, which is equivalent to observing a pair of fireflies in Tokyo from one's home in Maryland. This level of precision is 10 to 20 times better than the typical resolution of large ground-based telescopes. The telescope has revealed a new level of intricacy and complexity in various celestial phenomena, from nearby stars to galaxies at the limits of the observable universe.

It may come as a surprise that the human eye can perceive approximately 7,000,000,000 colors. However, there exist colors that are imperceptible to the human eye. In space, colors remain unchanged as the wavelengths remain constant. Although all colors of the rainbow and their mixtures are visible, the human eye only has three color detectors, known as cones, which have a preference for a specific type of light.

Every object reflects light into the eye, which reaches the small, medium, and large cone cells located in the eye. Each cell reads a wavelength, and the cones transmit a message to the brain, indicating the amount of long, medium, and short wavelength light that bounces off an object. This information is then translated into a numerical code that we refer to as color. Although light does not possess a color, the brain generates a code when the spectrum of light enters the eye.

If we were to combine all the light emanating from galaxies (including the stars within them) and from all the clouds of gas and dust in the Universe, the resulting color would be very close to white, but with a slight beige tint. However, when averaged over the entire sky, this beige color is diluted and appears almost, but not quite, black.

Given the vast expanse of the Universe and the abundance of stars, it may seem surprising that the sky is not bright white. This is because the Universe has a finite age, and the light from the farthest stars has not yet had enough time to reach us.

Researchers often add artificial colors to focus on a particular element or feature they are studying. Assigning colors to different wavelengths enables them to gain a better understanding of each object. Infrared, microwaves, and radio waves emit deep reds, while ultraviolet, X-rays, and gamma rays emit deep violet colors. Although the Hubble telescope can detect wavelengths that are invisible to the human eye, scientists also color them to maintain our interest in space.