{"id":472122,"date":"2024-12-31T03:05:21","date_gmt":"2024-12-31T01:05:21","guid":{"rendered":"https:\/\/osr.org\/?p=472122"},"modified":"2024-12-31T03:05:35","modified_gmt":"2024-12-31T01:05:35","slug":"why-is-space-black","status":"publish","type":"post","link":"https:\/\/osr.org\/en-uk\/blog\/osrguide\/why-is-space-black\/","title":{"rendered":"Why Is Space Black?"},"content":{"rendered":"

When you take the time to gaze at the night sky, chances are you\u2019re focusing on things like stars, planets, and, with a little luck, maybe even meteors<\/a>. But what about all the space in between those objects? The universe is filled with stars, galaxies, and nebulae that glow in all manner of breathtaking colours. Yet, the backdrop to this cosmic display is an expanse of deep, inky darkness. So, why is space black?<\/span><\/p>\n

That\u2019s where this article comes in! Join us as we take a closer look at the very fabric of space and try to get to the bottom of exactly why space is black!<\/span><\/p>\n

The Nature of Darkness in Space<\/span><\/h2>\n

\"A<\/p>\n

To understand why space is black, we first need to explore what darkness actually is. You see, as humans, we\u2019re very good at recognising \u2018things\u2019. It\u2019s just how our minds work. And that\u2019s fine when we can look at something like a star, or a planet, or a cat, and say \u201cOh, that\u2019s <\/span>something<\/span><\/i>\u201d. But the darkness of space isn\u2019t a tangible thing. It\u2019s the absence of light. It\u2019s not <\/span>something<\/span><\/i> – it\u2019s <\/span>nothing<\/span><\/i>.\u00a0<\/span><\/p>\n

Here on Earth, darkness is a fleeting phenomenon. The Sun\u2019s rays bathe our planet in light during the day, and even at night, the Moon and artificial lights chase away the gloom. But space? Now that\u2019s a different story entirely.<\/span><\/p>\n

Space is vast. Mind-bogglingly vast. It\u2019s mostly made up of vacuum, meaning there\u2019s very few particles to scatter or reflect light. And without something to bounce off, light will indefinitely travel in a straight line. So, unless you\u2019re looking directly at a light source, like a star<\/a>, your eyes won\u2019t perceive anything. Hence, the blackness of space.<\/span><\/p>\n

Then there\u2019s the small matter of how our eyes work. To see an object, light has to enter your eyes and stimulate the photoreceptor cells in your retinas. When you look at the night sky, only the light from bright objects like stars and planets reaches your eyes. The rest of space, where light doesn\u2019t directly hit your retinas, appears black.<\/span><\/p>\n

Interestingly, if you were to stand in space with no atmosphere to scatter light, even the Sun\u2019s rays wouldn\u2019t illuminate the surrounding void. Instead, the Sun<\/a> would appear as a blindingly bright point against a pitch-black backdrop. That\u2019s why astronauts see a black sky even when orbiting Earth in broad daylight.<\/span><\/p>\n

Why Is Space Black and Not Completely Bright?<\/span><\/h2>\n

\"Why<\/p>\n

At first glance, it might seem like the universe should be blazing with light. I mean, there\u2019s literally trillions of stars scattered right across the cosmos. Surely their combined glow should make space a dazzling spectacle?<\/span><\/p>\n

This question, known as Olbers\u2019 Paradox<\/a>, puzzled astronomers for centuries. But the answer lies in the nature of the universe itself. For starters, the universe<\/a> is not infinite in age. In fact, it\u2019s about 13.8 billion years old. Now, that\u2019s important, because it means the light from stars farther away than 13.8 billion light-years hasn\u2019t had enough time to reach us yet.\u00a0<\/span><\/p>\n

What\u2019s more, the universe is continually expanding. As it grows, it stretches the light from distant stars into longer wavelengths that are no longer visible to the human eye. This phenomenon, called redshift, also contributes to the darkness of space.<\/span><\/p>\n

Cosmic Voids: The Dark Side of the Universe<\/span><\/h3>\n

Astronomers estimate there to be 200 billion galaxies in the observable universe<\/a>, filled with trillions of stars. But despite these massive figures, they\u2019re still vastly outnumbered by empty regions called cosmic voids. These mammoth spaces, some spanning hundreds of millions of light-years, contain hardly any matter at all.<\/span><\/p>\n

Cosmic voids are another key reason why the universe appears black. Even though light travels through these regions, there\u2019s just nothing within them to emit, scatter, or reflect that light. As a result, they don\u2019t alter the straight-line travel of light passing through, and instead contribute to the swathes of darkness that dominate our view of the cosmos.<\/span><\/p>\n

Why Is Space Black – The Role of Light Physics<\/span><\/h3>\n

Compared to right here on Earth, light behaves differently in space. On our planet, the atmosphere scatters sunlight, creating the bright blue sky we see during the day. But in space, there\u2019s no atmosphere to do this. As we\u2019ve already mentioned, light travels in straight lines until it interacts with an object, like a planet, moon, or spacecraft. So, without something like an atmosphere to scatter or diffuse it, light doesn\u2019t \u2018fill\u2019 space the way it fills our sky.<\/span><\/p>\n

Also, it\u2019s worth considering the wavelengths of light. Visible light makes up just a tiny fraction of the electromagnetic spectrum. Much of the light in the universe exists in wavelengths that are invisible to human eyes, like infrared, ultraviolet, and X-rays. So, even though space is brimming with light, much of it simply isn\u2019t visible to us!<\/span><\/p>\n

Does Space Have Colour?<\/span><\/h2>\n
https:\/\/youtu.be\/3tCMd1ytvWg?si=CcJH1bfgilDf9xcO<\/a>