How do we have the equipment to picture and see cosmos and stars millions of light years away, but can’t just zoom-in to examine and view the surfaces of our interplanetary planets in the solar system?
In: Physics
Keep in mind that some of the things that are very far away (at the edge of what the telescope can see) only show up on a few pixels in the detector.
TL;DR The far away things are super big and super bright (a billion billion atomic bombs going off at the same time) so easy to see from a distance and the detail is lost.
This was asked before and here is the short answer:
The same way you can take a picture of a moving car 500m away and see it clearly but can not take a good picture of a flying fly 10cm away, and it gets worse when you zoom in.
Is all about brightness and relative speed
With stars, often no matter how much you zoom in they actually don’t get bigger in the image. It’s just a dot of light.
A lot of images of nebula are actually not that small in the sky but instead very dim. We open the telescope for minutes to hours to even days to collect enough light to see these images.
So how do we even find these exoplanets? Well we stare at a star and watch its light, and when the light dims consistent to a planet passing in front of it in orbit, we’ve found a planet. We can then study the light and actually even tell what it’s made up of by how it absorbs light.
It’s wild.
Cameras are made up of grids of little light sensitive squares. If light hits anywhere in the square it gets measured and makes that spot in the image lighter.
Stars are much much much much smaller than one square, but they put out so much light that it’s still enough to register as a white spot in the image.
So we know the star is actually somewhere within that square (pixel) but there is no way to know where inside of the square it is. It’s a bit like seeing the lights on in a house miles away. You can see clearly that their light turned on so someone is home, but your eyes can only see a spot of light turn on and off.
Even if you are many miles away you can see a light turn on and off but you can’t actually make out any shapes.
We can make a lot of very useful observations about a house miles away, we can see the light’s color, is it a blue led, is it a warm incandescent light, is it a greenish fluorescent? We can even infer that someone is walking around in front of a window if the light level dips. We can communicate using the window by flicking the switch on and off to send ~~Moore’s~~ Morse code.
But ultimately our understanding has no 2 dimensional resolution. There is lots of ways to study a point of light but the stars are still just points.
The surface of Mars can be studied in a similar fashion as the cosmos are studied inspecting Mars as a single point of colored light, but if you want a picture to hang on the wall you need to get closer or build a far larger telescope.
As to why we get pictures of Nebula from earth but not clear pictures of Mars, the answer is that while they are very far away they are so immensely large that the distance makes them appear bigger. It’s much like how how a billboard across the street can look larger than a stamp in your hand. It’s easier to photograph the billboard because it appears larger.
Many objects that are extremely far away such as galaxies are also large enough (tens of thousands of light years across) that they would actually appear very large in our sky if they were brighter. For example M31: Andromeda Galaxy is over 2 Million Light Years away, but its apparent angular size in our sky is over 3 degrees. By comparison, a full moon is roughly half a degree across, meaning that the full major axis of Andromeda occupies 6 times as much space in our sky as a full moon. The only limiting factor that prevents us from seeing it with our eyes is its dimness, but this can be remedied with high aperture telescopes and cameras that are much more sensitive to light than our own eyes.
Now let’s think about planets. For a large portion of the year, Jupiter has the largest apparent size of any other planet in our sky, it varies between about 30-50 arcseconds. An arcsecond is 1/360 of a degree, much smaller than the moon or Andromeda, but not too small resolve a decent amount of surface detail by powerful telescopes with sufficient focal lengths. Pluto on the other hand varies in apparent size from 0.06-0.11 arcseconds, meaning that the limitation on seeing detail on Pluto is not dimness, but size.
How come you can see someone across the street just fine but can’t zoom in to see the bacteria on your hand?
Stars are very large and very bright, planets are very dark and comparatively small, distortions by our atmosphere mean that picking out details is difficult, but space telescopes are better.
Not answering OP but I’m kinda pissed for like all my life that we don’t have a streaming cam pointed to our own planet.
I mean, it’s not like we don’t have the technology so…. why not have one single 4K cam pointed at Earth spinning, 24/7.
And no, I know we have pictures movies whatever, I WANT A STREAMING CAM, like those you people pay in porn, but pointed AT EARTTHHHHH
Most of our zooming in actually reconstructions of different spectographs (measures specific wavelengths of light), recordings of radio emissions (more random than talk shows, but just as informative if you listen in high def), and filling in the gaps with scientific guesses.
These processes are different for each type of feature of the galaxy, especially planets. Many planets reflect information around them but don’t produce any information about themselves.
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