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Why Do Planets Look Like Stars [And How To Tell The Difference]

Planets and Stars can appear almost indistinguishable when observed with the naked eye. Lots of people wonder why this is. I got curious too, so I did some research. Here’s what I found.

Why Do Planets Look Like Stars? Despite being fundamentally different, Planets Look Like Stars and vice versa due to their relative distance from us on Earth. Planets are much closer to us in the Solar System and reflect the light of the Sun. Stars on the other hand produce their own light but are increasingly further away from our Solar System. 

When observing Planets and Stars, it is important to consider the intrinsic differences, and from there you can start to understand and to differentiate between the two.

Why Do Planets Look Like Stars

The planets in our Solar System are much closer to us on Earth. Despite the fact that the planets are considerably smaller than the stars, planets appear to be about the same size as the stars due to the distance away from us.

Alternatively, the stars are considerably further away from us on Earth, giving off the illusion that they are smaller, despite the fact that up close they are large.

What About Stellar Scintillation (Twinkling)

If you are wondering why the planets and stars both visually appear similar, and why you can see them to begin with, it is due to their relationships with light.

Planets do not produce their own light, but they do reflect the light of the Sun in the same way the Earth’s Moon reflects sunlight. This is known as the Albedo effect.

Stars on the other hand, do produce their own light. This is similar to our sun (the sun is a star; and its the the closest star to Earth).

But what about Twinkling?

Stellar Scintillation is the scientific name for the twinkling of stars. In other words, its the shine or the glow that stars appear to emit. You can use this to help distinguish between the stars and the planets.

If you was to lookup in the night sky, you would notice that most, if not all starts twinkle.

This will appear far more prominent on windier nights. This is because a star is a single-point light source.

Its light has to pass through different layers of atmospheric conditions (molecules and particles) before it reaches us on Earth and hence, there is a twinkling effect.

This will be more noticeable when the a star is in closer proximity to the horizon, because in essence, light has to travel through more of the atmosphere.

If you observe closely, you will notice than among twinkling stars, some do not appear to be twinkling.

These are the planets in our Solar System. The fact that they do not twinkle is due to their disk-like surface area and its relationship with the atmosphere.

How To Tell The Difference Between Planets and Stars

To differentiate and tell the difference between planets and stars, you will need to alter your Angular Resolution/Spatial Resolution.

This is basically the ability to distinguish and identify the finer details of an object. It is the mechanism in play that enables you to focus and determine resolution on an object.

Angular Resolution applies to all image-forming devices, so whether it is your naked eye, a microscope, camera or telescope, you can manipulate it in your favor.

So when it comes to observing the sky with your naked eye, when it comes to planets and stars – you’re going to be able to see something bright but you’re not going to be able to resolve any features beyond the fact that it looks like a bright point.

This is where Telescopes excel.

Telescopes have an greatly improved and increased resolving power (magnification) compared to your eye and they’re also better at collecting light.

As light is what enables us to see objects in the sky, collecting more of it is essential to observing more. (Telescopes that collect more light are typically considered better and are more costly).

Ultimately, your eye is not able to view planets as disks and instead, it can only see them as points of light.

A capable telescope enables you to view the Planets and Stars a lot more closely, and ensures you can study and observe their intrinsic and unique features.

Other star guides you may want to check out: