The Vastness of Outer Space Is Incomprehensible

We inhabit a planet’s surface, unaware of the true magnitude of space.

Photo by Guillermo Ferla on Unsplash

British spelling.

We successfully sent men to the Moon and are contemplating sending men and women to Mars, but the red planet is just a step away when we think of the solar system’s size and is minuscule compared to the universe.

We always think about distances, like how many kilometres or miles are between our home and workplace or the distance needed to travel before reaching a holiday destination.

The diameter of the Earth is 12,742 kilometres (7,918 miles), the distance to the Moon is 384,400 kilometres (238,855 miles), and the Sun is almost 150 million kilometres (93 million miles) from the Earth. We can understand these distances, but space is different; its size can be beyond our comprehension.

The American space probe New Horizons was launched from Cape Canaveral, Florida, in January 2006. Its most important objective was to fly by the dwarf planet Pluto.

It achieved that journey in July 2015, passing by Pluto at a distance of just 12,550 kilometres (7,800 miles) from its surface.

New Horizons continues its journey through space. As of May 2024, it is 58 astronomical units (AU) away from Earth.

One astronomical unit (AU) is the average distance between the Sun and the Earth — almost 150 million kilometres (93 million miles).

Given that the average distance between Earth and Pluto is approximately 5 billion kilometres (3.1 billion miles), it’s understandable that New Horizons took 9 years, 5 months, and 25 days to reach its destination.

Photo by NASA on Unsplash

New Horizons passed Pluto travelling at a speed of roughly 58,000 kilometres per hour (36,000 miles per hour). I’ll use that speed in the following comparisons.

Travelling from the Earth to the Sun (1 AU) at that speed would take New Horizons over 107 days.

The Sun’s closest star neighbour, Proxima Centauri, is just over 4 light-years away, or roughly 40 trillion kilometres (25 trillion miles).

Hypothetically, New Horizons would take more than 79,000 years to reach it. And yet, Proxima Centauri is still considered relatively close in cosmic terms.

The Solar System, in contrast, has a diameter of about 100,000 light-years, which is 946 quadrillion kilometres (588 quadrillion miles). Wow!

For reference:

A trillion is a 1 followed by 12 zeros.

A quadrillion is a 1 followed by 15 zeros.

Yes, these numbers are hard to fathom.

Sagittarius A* is the name of the black hole at the centre of our galaxy, the Milky Way. It is over 25,000 light-years from the Sun.

Once again, how long would it take our little spacecraft, New Horizons, to reach it? At its current speed, the journey would take an astonishing 465 million years.

The closest spiral galaxy to the Milky Way is Andromeda, also known as M31. On a clear night, it can be seen with the naked eye. Its distance from our galaxy is over 2.5 million light-years.

In a hypothetical scenario where the two galaxies remained at a constant distance from each other, New Horizons would take more than 47 billion years to travel the distance between them — nearly three times the current age of the universe.

And yet, in cosmic terms, Andromeda is still in our local area.

Thanks to advanced telescopes, we can now observe objects over 13 billion light-years away. Trying to calculate how long New Horizons would take to reach those distant places is futile — the numbers involved are simply too vast for most of us to grasp.

It’s unlikely that humanity will ever venture far beyond our local cosmic neighbourhood and embark on such extraordinary journeys.

The speed of light is 1,080 million kilometres per hour (671 million miles per hour). But only light can move that fast. Even if we could achieve that speed, it still wouldn’t be fast enough — our short lives would end long before we got very far.

Photo by Leo_Visions on Unsplash

Speculation about the existence of intelligent life elsewhere in the universe is common. But getting clear answers is unlikely, given the unimaginable distances involved.

Is it conceivable that highly advanced life forms have discovered faster ways to travel between points A and B?

If so, surely we would have heard from them by now.

Yes, the universe is vast. As mentioned, we can now see objects that are more than 13 billion light-years away, but over that immense period of time, the universe has continued to expand.

Current estimates suggest that the universe today has a diameter of over 90 billion light-years.

I hope this brief article has provided a sense of scale regarding the vastness of the universe.

The end.

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