What are the saddest truths about exploring outer space?

 This is Kepler-186f, the first planet discovered with a radius comparable to Earth's, located within another star's habitable zone.

However, Kepler-186f sits more than 550 light-years away from Earth, and a single light-year spans roughly 5.9 trillion miles. In other words, what we're currently observing of Kepler-186f actually represents how it appeared over 550 years in the past.

Discovering Kepler-186f confirms that Earth-like planets genuinely exist within habitable zones elsewhere. That said, given its distance exceeding 550 light-years, it remains too far for current telescopes, or even upcoming next-generation instruments, to gather further details (meaning the image above is essentially just artistic interpretation). No further specifics regarding its actual habitability have surfaced yet, and realistically, given current technological limits, we shouldn't expect meaningful breakthroughs anytime soon.

My childhood fascination with astronomy eventually shaped me into an agnostic atheist. While I don't personally believe in any deity, it genuinely feels like the universe remains, and will likely always remain, beyond the full grasp of Earth's intellectuals, seemingly destined to stay a permanent mystery to life here.

As a kid, I marveled at incredible discoveries made by countless scientists throughout history and the sheer brilliance of human intellect, yet simultaneously felt stunned by how utterly insignificant and brief human existence appears on a cosmic scale. Our sun, over a million times larger than the planet we inhabit, represents merely one among 300 billion stars within the Milky Way, itself just one galaxy among billions scattered throughout the universe. And multiverse theory proponents even suggest multiple universes might exist simultaneously.

Much like countless unresolved questions, how life originated on Earth, how consciousness actually functions, the true nature of time itself, philosophers and scientists have wrestled with understanding the universe for millennia; it remains so fundamentally and profoundly complex that full human comprehension may forever stay out of reach. Perhaps the universe was simply never meant to be entirely understood.

It's genuinely disheartening realizing humanity faces such hard, unavoidable limits, and nothing illustrates this reality more clearly than space exploration itself.

What is the biggest myth about outer space?

 The biggest myth about outer space is in the name: Space.

Everyone thinks it’s empty.

I mean, why wouldn’t they? It says right there. Outer. Space.

So, why wouldn’t anyone think it’s anything but a vacuum!

Well, it’s not!

It’s teeming with a lot of stuff and activity. Just not as much as on Earth or any heavenly body, but enough to matter (no pun intended).

Image Credits: Stock photo, pixabay.

So, What’s Filling Up the Space?

Well, some of the things are familiar to us – atoms, dust, plasma, radiation, and so on.

Of course, when you leave the Earth and enter outer space, the matter density drops to negligible levels. There’s no question about that.

But, even in that seemingly vacuous space, there’s quite a bit of stuff, although not in any meaningful quantities for us to bother about it.

Think of it like this: On Earth, you have a high density of matter. As you fly into outer space, the density keeps dropping until you exit the atmosphere, when it hits negligible levels. Then, as you approach another planet, the density increases from negligible levels to a meaningful degree.

But, The Density Changes Too

Stars like the Sun have a kind of bubble or sphere of influence that can extend for light-years.

Within this halo, you’ll find an abundance of solar storms, coronal mass ejections, and other activity adding to that density.

So, matter density within this heliosphere is usually higher than what it is in the space between stars, which is even more sparse.

Things get really interesting between galaxies.

This is where matter density is the least. Lower than what’s in both interstellar and stellar systems’ space.

In short, intergalactic space is the least dense, followed by interstellar space within galaxies, and finally the stellar system space.

In general, there’s about 1 atom per cubic centimeter of interstellar medium. The intergalactic medium has an even lower average density of 1 atom per cubic meter.

And, There are Exceptions

So far, we’ve discussed only the regular baryonic matter that makes up the things we know – planets, air, water, life, etc.

But that’s not everything.

There’s the more exotic stuff you won’t easily find on Earth: cosmic rays, dark matter, neutrinos, and dark energy. Dark matter is present within galaxies, and sometimes, outside too.

And every square inch of space is bombarded with hundreds of billions of neutrinos per second, especially in stellar systems.

And the ever-present quantum fluctuations don’t relent just because you are in outer space.

Vacuum energy, or zero-point energy, pervades the space, even in regions with the lowest energy density.

In a Nutshell

Think of outer space as an extremely low-density region with a lot of activity happening in it.

It’s not some inert, empty vacuum. It’s bubbling with activity, especially within galaxies.