When you gaze up at the night sky, it may look like an endless void. But is there any place in the solar system or beyond that stands out as particularly dark? Experts suggest that the answer isn’t as simple as it seems.
True darkness, the kind you might expect, is rare in space. This is largely due to cosmic dust, which scatters light and creates a background glow throughout the universe. Astronomer Marc Postman of the Space Telescope Science Institute explains that this glow gives the universe a beige hue, whimsically dubbed “cosmic latte.”
Defining darkness also plays a role. Andreas Burkert, a theoretical astrophysicist at the University of Munich, states that different wavelengths of light, such as gamma rays and ultraviolet rays, can illuminate certain areas, adding to the complexity of what we perceive as dark.
However, when focusing on visible light, several areas in space qualify as extremely dark. First, certain celestial bodies, like comet Borrelly, absorb nearly all light, reflecting less than 3% of sunlight. Its nucleus is among the darkest places in our solar system, as noted by the Guinness Book of World Records.
On a larger scale, the exoplanet TrES-2 b is even darker, reflecting less than 1% of light. This darkness is attributed to high amounts of sodium vapor and gaseous titanium oxide in its atmosphere. For comparison, Earth reflects about 30% of sunlight.
Interestingly, light also behaves differently around black holes. Though they capture light within their event horizon, they can trap it in such a way that makes the surroundings appear dark. Yet, if you were to enter a black hole, you’d experience an intense brightness, as Burkert describes.
Darkness can also occur where light is obstructed. Certain craters on the Moon, especially those near its poles, remain in constant shadow, making them incredibly dark locations. Similar dark spots exist on Pluto as well, due to their distance from the Sun.
Beyond this, you can find regions in space known as Bok globules, composed of dense dust. These areas appear as voids in the sky because they block visible light from surrounding stars. However, they may not be as dark in the infrared spectrum, revealing a complex relationship between light and matter. Burkert has studied such regions, including one called Barnard 68, located about 500 light-years from Earth.
New research shows that some areas far from light sources are significantly darker. According to a 2021 study published in The Astrophysical Journal, these distant regions are, on average, ten times darker than what we see near Earth. Yet, there’s still some background light present.
Interestingly, Earth finds itself in a relatively dark spot within the Milky Way. Burkert points out that this unique position allows us an unobstructed view of the cosmos. He stated, “We sit in the middle of this big bubble, and so we can see a lot of stars.” This highlights how our understanding of space, light, and darkness can shape the way we explore the universe.
