Scientists Explain: If We Can See Stars Billions of Light Years Away, Why Can’t We See What’s on the Moon?

A common question or misconception about our capabilities to see objects in space is how we can see stars billions of light-years away, but we can’t see the finer details on what’s on the moon, such as the footprints of the astronauts who landed there, or the national flags.

Let’s unpack how this phenomenon is possible. Additionally, we’ll discuss which tools will allow us to see the other smaller objects we have left on the moon, such as moon rovers, spacecraft, human waste, and more.

Optical Resolution Limits in Camera and Eye

Whether it is your eyes or a high-resolution camera, there isa limited ability to distinguish fine details, known as its optical resolution, especially if the objects being observed are small and very far away. This phenomenon is often expressed or described as an angular size or resolution.

It refers to the smallest angle between two objects that a camera or human eye could perceive. It usually is around 1 arcminute, the unit of measurement of angular resolution. According to NASA, because the moon is about 30 arcminutes, we can only perceive about 30 pixels of detail, translating to an area of about 110 km.

In other words, anything less than that size, in the specific distance of the moon, is not perceivable by the human eye or cameras because we do not have the biological capability to resolve the finer details.

So it means the objects we left on the moon, such as the national flags, human waste, or the spacecrafts, are all too small for us to see. However, this is not the only reason, so let’s discuss a few more.

Read more: NASA

Bright Moonlight Overpowers the Dim Stars

Why don’t we see stars in space? #apollo #moonlanding Full video - https://youtu.be/fMHLvoWZfqQ

Have you ever looked at something bright, only for you not to actually see what it is? It is the same case for the moon, even if it is not as shiny as the sun. The bright moonlight can still overwhelm camera sensors and our eyes.

If we try to fix it, such as by using auto‑exposure settings for the Moon, the resulting photograph will leave stars invisible. This is because the moon is reflecting the light of the sun, making it really bright, unlike the other stars, which are very faint and will need a longer exposure time to be captured by a camera.

We Always See the Same Side — Tidal Locking Explained

There is a phenomenon called tidal locking, and our moon is a good example of it. This is an event that refers to celestial bodies having an orbit that is synchronous to another body, making them always face-to-face.

Our moon is the same; it is tidally locked, so we always just see the front side facing the Earth, and the hidden far side actually remained a mystery until 1959.

Read more: WIRED

Telescope Resolution: Still Too Little for Footprints

Next are our advanced technologies like the James Webb Telescope and the Hubble Telescope, both of which could allow us to see galaxies from billions of light-years away, but still couldn’t capture a footprint on the moon.

This is because, according to NASA, even the most powerful telescope of mankind, the James Webb Telescope, can’t resolve features smaller than a few hundred meters on the Moon. Unfortunately, the technology was perfect for its intended function, which is to see as far away as possible.

They were not developed to see smaller objects, but instead aim to study distant stars and galaxies across the universe. However, we still could actually see the Apollo landing sites and footprints by using lunar orbiters such as the Lunar Reconnaissance Orbiter, which can capture image details down to 0.5 m.

Why Can't We See the Dark Side of The Moon?

Author's Final Thoughts

It is a common misconception to compare our ability to see objects in space billions of light-years away, and our competence in seeing smaller objects in far nearer locations, such as the moon. However, it is not because humans have not really landed on the moon, or because of other conspiracy theories.

It is simply because the objects from farther away that we can observe are unimaginably massive and bright, while the small objects on the Moon simply fall below the limits of our eyes and instruments from Earth.

Read more: Hundreds of Stars Vanished Without a Trace — And Scientists Might Finally Know Why