Look up at the Moon on a clear night. It’s big, it’s bright, and even a simple telescope can reveal most of it’s details.

But why has no one been able to see astronauts here from earth with a really powerful telescope?

Or why can we not see objects left on the moon from previous lunar landing missions?

A question that sounds simple but has a deeply scientific answer.

Lets dive right into it.

Or you can watch my video if you want to skip this article:

1.It’s Not About Zoom 

Most people assume this is a magnification problem. Get a big enough zoom, and you’d see everything, right?

Wrong. And this is the key misconception.

In astronomy, it doesn’t matter how much you magnify an image, it’s how much detail you can capture and resolve.

These are completely different things.

Think of it like this: if you take a blurry photo and zoom in, you don’t get a clearer photo.

You just get a bigger blurry photo.

The sharpness of detail a telescope can capture is called its resolution, and it’s governed by the laws of physics themselves.

And the primary physics is…

2.The Diffraction Limit 

Light is a wave. When it passes through the circular opening of a telescope, it bends and spreads, this is called diffraction. 

And it fundamentally limits how sharp your image can ever be.

The science is elegant. The bigger your telescope’s mirror, the better its resolution. 

But the Moon is 384,000 kilometres away and its diameter is 3,475 kilometres. 

Thus, a full moon appears at an angle of 0.5 degrees or 1,800 arcseconds in the sky. 

Here’s the formula:

Θ (in arcseconds) = 206,265*(Moon’s Diameter)/(Distance from Earth) = 1,864 arcseconds

To convert this into degrees, divide arcseconds by 3,600 and that gives you ~0.5°.

Now, an astronaut standing on it is just about 1.8 metres tall.

And at that distance, the astronaut appears at an angle of roughly 1/1000 of an arcsecond in the sky.

And an arcsecond is already just 0.00028 (1/3,600) degrees. 

We’re talking impossibly, vanishingly small.

To resolve something that tiny, you’d need a telescope mirror roughly 116 metres wide, nearly the length of a football field.

The largest telescope mirror on Earth today?

About 39 metres, still under construction. The ELT (Extremely Large Telescope)

The Hubble Space Telescope is just 2.4 metres. And James Webb is 6.4 metres

Magnitudes shorter than what’s needed on the ground.

But even if you had Elon kind of money and you were able to build that 116-metre telescope mirror, you still wouldn’t be able to see the astronauts, and this is the final nail in the coffin.

3.And Then There’s the Atmosphere

Every time light from space travels down to your telescope, it passes through kilometres of turbulent, moving air. 

Different temperatures, different densities, all constantly shifting.

This bends and scrambles the light, blurring the image. It’s the same reason stars appear to twinkle.

This effect, called astronomical seeing, limits even the best ground-based telescopes to a resolution of about 0.05 arcseconds under ideal conditions.

We need 0.001 arcseconds. The atmosphere gives us 0.05.

That’s 50 times too blurry, no matter how big your mirror is.

Building a 116-metre telescope on Earth would be a multi-billion dollar, decades-long engineering feat…

And the atmosphere would still render it useless for this specific goal.

So What ‘CAN’ We See?

Here’s what’s fascinating, though. The Lunar Reconnaissance Orbiter, a NASA spacecraft that orbits the Moon at just 50 kilometres above its surface, ‘has’ photographed the Apollo landing sites.

And in those images, you can actually make out the descent stage of the lunar lander, equipment left behind, and even the dark trails left by astronauts’ footsteps and rovers in the lunar dust.

The trick wasn’t a bigger telescope. It was getting closer.

So, there you have it.

The Moon feels close. But when you’re trying to spot a 1.8-metre human standing a quarter of a million miles away, the laws of physics have very firm opinions about what you’re allowed to see.

Next time you look up at the Moon, just know that a dozen humans have walked up there. You just can’t see them from here. 

And now you know exactly why.

If you enjoyed this post, then you may enjoy my posts on ‘6 Unknown Facts About Moon Landing‘ or ‘How Moon Landing Changed the Everyday Life‘