The vast distances between the stars.

The space between the stars is vast.

Using our own unaided vision about 5,000 stars are visible from the surface of our planet, but the Earth itself gets in the way and restricts what we can see, therefore we can only see about 2,500 stars from any one viewpoint on our planet.

Proxima Centauri is the Sun's closest star neighbour, it lies over 40 billion kilometres away. To make that statement easier to understand, imagine this.

The distance between the Earth and the Sun is almost 150 million kilometres or one astronomical unit. Proxima Centauri is almost 269,000 astronomical units from our local star the Sun.

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This may be a good time to think about the speed of light.

Photo by Mathew Schwartz on Unsplash.

In a vacuum, light travels at almost 300,000 kilometres each second.

Light is so important in many areas of physics. We can also use its speed as a measure of distance.

So what is the speed of light? It works out at 18 million kilometres per minute or 1,080 million kilometres per hour. Yes, that speed is a bit mind-boggling, to say the least.

Anything that has mass could never reach the speed of light, the vast amount of energy needed would be impossible to achieve.

Could it be possible that in the future we will be able to reach distant areas in space nearing the speed of light? I think we can rule that scenario out. The most that we can hope for is to visit objects in our own solar system which is of course our own backyard.

The Parker Solar Probe was launched into space in 2018, its mission is to study the Sun and its outer corona. In 2025 it will make its closest approach to the Sun and is expected to achieve a speed of roughly 690,000 kilometres per hour. But even at that speed, we are never going to get very far from our local area in space.

The next few lines will hopefully put the speed of light into some sort of perspective.

Light speed is 1,565 times faster than the maximum speed the Parker Solar Probe will be able to achieve.

Our natural satellite, the Moon lies 384,400 kilometres from the Earth; light leaving the Moon would take just over one second to reach the surface of the Earth.

The circumference of our planet is just over 40,000 kilometres. If it was possible for light to zip around the Earth's surface, it would do so 7.5 times each second.

The distance between the Earth and the Sun is almost 150 million kilometres; that short journey for light takes only 8.3 minutes.

As I mentioned before Proxima Centauri is a small, low-mass star located almost 40 billion kilometres from the Sun. Not including the Sun, it is our nearest star neighbour but light leaving Proxima Centauri would take over 4 years to reach us.

You may think that Proxima Centauri is very distant but in reality, it is just a step away when considering the size of our galaxy, but how big is our galaxy? light would take over 100,000 years to travel across the width of the Milky Way.

But our galaxy is minuscule compared to that gargantuan area we call the Universe.

With highly advanced telescopes, we can now see objects that are over 13 billion light-years away. It is very hard for us to comprehend these vast distances.

Imagine, for every year of that 13 billion years the light from those extremely distant objects will have travelled 9.46 trillion kilometres towards us.

I could write down the number of kilometres or miles but it would be meaningless to most of us. Yes, they are mind-boggling astronomical distances.

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You may enjoy reading some of my easy-to-understand articles regarding the Universe and Life.

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