What would the planets look like in real life?

[Nathi ORea]

TL;DR

I have wondered what the various planets would look like if you actually were in a spacecraft looking out the window?

I am of the total understanding that most astrophotography pictures are not a real representation of what objects actually look like... I guess I mean, it is not an accurate representation of what things would look like if you were actually the same distance closer as the picture's magnification and you simply looked out the window of a spaceship.

I have often wondered about the planets but. For instance, pictures of Jupiter are absolutely stunning, with the swirls of clouds, and all the different colours and whatnot.

Like.. Why doesn't it look anything like that when you look at it through a telescope. You see some cloud bands and maybe the Great Red Spot. You absolutely see nothing like the detail in photos. It makes me wonder if pictures of the planets are filtered or altered in some way. I have always been a pov guy. Like I want the experience of what things would actually look like if you were there.. with your own eyes.

... and I guess my other question would be.. If pictures from the various spacecraft are a pretty accurate representation of how the planet actually looks (perhaps the same as snapping it with your smartphone) then why does a planet (let's stick with Jupiter) look so plain when you look at it through a telescope... Atmospheric affects etc?

Anyway.. I am looking forward to any ideas.

 

[Ibix]

There are quite a few astrophotographers around here. Have a look through the "Our beautiful universe" thread stickied at the top of this forum.

Examples:
Saturn
Jupiter
Mars

 

[Melbourne Guy]

@Nathi ORea, SpaceEngine provides as realistic as possible representations of planets and other celestial bodies, if you're up for installing a very large application! But to answer your question, depending on the purpose of the image, it may have false colour overlays or be made up of multiple exposures. But your question verges into the philosophical because even 'our own eyes' lag due to biological filtering and what does anything "actually look like", anyway? Visual reality has a subjective element to it, as optical illusions highlight.

 

[russ_watters]

Like.. Why doesn't it look anything like that when you look at it through a telescope. You see some cloud bands and maybe the Great Red Spot. You absolutely see nothing like the detail in photos. It makes me wonder if pictures of the planets are filtered or altered in some way.

There's two separate issues here:
1. Colors are denatured when looking through a telescope because of different sensitivity of rods and cones.
2. Optical resolution is much worse than what you see in photos.

If you were near the planet, it would look more like the photos.

 

[Drakkith]

I have often wondered about the planets but. For instance, pictures of Jupiter are absolutely stunning, with the swirls of clouds, and all the different colours and whatnot.

Like.. Why doesn't it look anything like that when you look at it through a telescope. You see some cloud bands and maybe the Great Red Spot. You absolutely see nothing like the detail in photos.

First and foremost is the extremely limited resolution that ground based telescopes have when it comes to visual use. This lack of resolution blurs all the colors and details together and you only see the 'big' stuff, like the large bands and sometimes the great red spot. Anything smaller is simply blurred into oblivion.

Jupiter is only 50 arcseconds across at its closest approach, which is less than 1/60th of a degree. Even the largest visual telescopes, some of which are greater than 20-inches across, are limited to about 1 arcsec worth of resolution thanks to turbulence in the atmosphere. And that's on nights with good 'seeing'. On bad nights the resolution is degraded upwards of 5x worse.

Ground-based telescopes that use cameras have the advantage of using something called 'lucky imaging'. This means they take thousands of images with exposures only a fraction of a second long over the course of a few minutes and then pick the best 1% or so to average together for the final image. The extremely short exposure times limits the amount of blurring that can be done by the atmosphere in each image.

In addition, the diffraction of light greatly limits what smaller telescopes can see. Even with perfect seeing an 8-inch diameter telescope can only get down to about 0.67 arcseconds of resolution, and that's assuming the optics were virtually defect-free. At best, Jupiter would be about 75 pixels across before you'd stop benefitting from further zoom. See this article to see what viewing a target looks like through different size telescopes.

With larger telescopes, the resolution can get better, but Jupiter is still so small that you just don't see very much. Even with a 20-inch telescope, which is absolutely massive for an amateur scope (though not even close to being the biggest amateur scope), the resolution is limited to 0.27 arcseconds, and you'd stop benefitting from zooming in once the image was 186 pixels across. And that's ignoring the blurring by the atmosphere, which usually prevents even this resolution from being reached.

Image processing can help a little bit, but the best images are taken by space probes which are near to the planet when they take their images.

 

[FactChecker]

IMO, most photographers want to make their photos as beautiful as possible. They will often increase saturation and contrast and apply some unsharp masking. I bet this is especially true of objects that they can not see without stacking photos because they can not see them without the camera and may not realize how unnatural the result is.

 

[TeethWhitener]

https://solarsystem.nasa.gov/resources/114/jupiter-in-true-and-false-color/
An example from NASA.

 

[Nathi ORea]

First and foremost is the extremely limited resolution that ground based telescopes have when it comes to visual use. This lack of resolution blurs all the colors and details together and you only see the 'big' stuff, like the large bands and sometimes the great red spot. Anything smaller is simply blurred into oblivion.

Jupiter is only 50 arcseconds across at its closest approach, which is less than 1/60th of a degree. Even the largest visual telescopes, some of which are greater than 20-inches across, are limited to about 1 arcsec worth of resolution thanks to turbulence in the atmosphere. And that's on nights with good 'seeing'. On bad nights the resolution is degraded upwards of 5x worse.

Ground-based telescopes that use cameras have the advantage of using something called 'lucky imaging'. This means they take thousands of images with exposures only a fraction of a second long over the course of a few minutes and then pick the best 1% or so to average together for the final image. The extremely short exposure times limits the amount of blurring that can be done by the atmosphere in each image.

In addition, the diffraction of light greatly limits what smaller telescopes can see. Even with perfect seeing an 8-inch diameter telescope can only get down to about 0.67 arcseconds of resolution, and that's assuming the optics were virtually defect-free. At best, Jupiter would be about 75 pixels across before you'd stop benefitting from further zoom. See this article to see what viewing a target looks like through different size telescopes.

With larger telescopes, the resolution can get better, but Jupiter is still so small that you just don't see very much. Even with a 20-inch telescope, which is absolutely massive for an amateur scope (though not even close to being the biggest amateur scope), the resolution is limited to 0.27 arcseconds, and you'd stop benefitting from zooming in once the image was 186 pixels across. And that's ignoring the blurring by the atmosphere, which usually prevents even this resolution from being reached.

Image processing can help a little bit, but the best images are taken by space probes which are near to the planet when they take their images.

Wow! Thanks for that. That really made a lot of sense. I really appreciate it. I have never really understood the whole diffraction limiting resolution thing in telescopes. I know the same thing happens in microscopes as well. I need to spend a bit of time understanding it. I know it would be important in understanding the nature of light..

I am not great at maths but.. lol

.. but I think you hit it out of the ball park on this one champ.

Thanks a million.

 

[glappkaeft]

One thing often overlooked is that the outer planets would be much dimmer than we are used since they receive much less sunlight.

 

[Vanadium 50]

would be much dimmer

Are you sure? Our eyes have essentially a logarithmic response.

 

[berkeman]

Our eyes have essentially a logarithmic response.

But with Cones --> Rods in the dimmer light, the colors would appear much more washed out, no? Road Trip!

 

[Drakkith]

One thing often overlooked is that the outer planets would be much dimmer than we are used since they receive much less sunlight.

They'd be much dimmer than looking at Earth, sure. But my living room is about 1/100th to 1/200th as bright as outside and I can still see everything just fine. Saturn gets about 3% as much light from the Sun as Earth does, so it's still roughly 3x-6x brighter than indoors. You'd have to get to Uranus before you'd start REALLY noticing the dimming.

 

[Vanadium 50]

I'm surprised its as high as 1%. Outside you have direct sunlight. Inside you have reflected light and windows are maybe 10% of the space. But even 1% means Saturn is illuminated about as well as it would be indoors. I would have guessed more like 0.1%, which gets you to Neptune, and Pluto when its close.

 

[Drakkith]

I'm surprised its as high as 1%.

This source says outside light is between 11,080–18,176 lux while indoor is roughly 112–156 lux. I too thought the difference was larger.

 

[hmmm27]

And, of course, there's the difference between "artist's conception" - which is really annoying - and actual photos where they've included frequencies that the human eye doesn't naturally see.

 

[TeethWhitener]

A calculation based on the info and formulas on Wikipedia’s absolute magnitude page gives Earth’s apparent magnitude from the moon at direct opposition (“full Earth”) as -16.5. Repeating the calculation for Saturn distance and absolute magnitude gives an apparent magnitude (“full Saturn” at opposition as seen from the Earth-Moon distance) of -16.54. So Saturn would actually be a bit brighter than Earth. Jupiter is left as an exercise for the reader.

 

[snorkack]

Full Earth disc is about 14 times the area of full Moon and about 3 times more reflective:
https://earthobservatory.nasa.gov/images/86353/the-dark-side-and-the-bright-side
The near side is darker than the dark side shown here, because of more seas.

 

[Drakkith]

A calculation based on the info and formulas on Wikipedia’s absolute magnitude page gives Earth’s apparent magnitude from the moon at direct opposition (“full Earth”) as -16.5. Repeating the calculation for Saturn distance and absolute magnitude gives an apparent magnitude (“full Saturn” at opposition as seen from the Earth-Moon distance) of -16.54. So Saturn would actually be a bit brighter than Earth. Jupiter is left as an exercise for the reader.

Interesting. I hadn't known that. However, Saturn is MUCH larger than Earth, so all that light is spread out over a much larger surface area. Saturn would be about 17.2 degrees in apparent diameter as viewed from the Moon's distance, compared to Earth's 1.87 degrees. Saturn would have over 84x the apparent area as Earth, reducing the relative magnitude per unit area of Saturn to... well, I'm not actually sure how to calculate that. In any case, it would look dimmer than Earth because our eyes don't sum to light from the entire field of view.