# How do we get other pictures of far away galaxies that we can not see?

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How do we get other pictures of far away galaxies that we can not see?

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Long exposures with cameras using powerful telescopes.

Many galaxies and other celestial objects are too faint to see with the eye, or with a regular camera. But if you let a camera have a long enough exposure these faint objects reveal themselves in the picture taken by the camera.

Often they use radio telescopes using wavelengths other than visible light, but we can “see” them just with additional assistance.

Big telescope capable of detecting faint light with long exposures and accurate direction. Launched up in space so the atmosphere doesn’t distort the view. Probably a bit of image processing to remove the last bit of distortion.

You end up with this, most of the blobs are separate galaxies billions of stars in each.

There are also some nifty physics tricks that can be used, such as gravitational lensing . Basically a massive object, like a galaxy, bend the light of an object behind it around it. This results in a magnification/amplification affect. Using some fancy math, astronomers can used this warped and distorted image to reconstruct the object.

Imagine that you eat a big burger. Will eating just one make you feel full? Probably yes.

Imagine that you eat popcorn. Will eating just one make you feel full? Probably not. However, if you keep eating more and more and more popcorn, at some point it will end up getting you full.

Replace the food with light and your stomach with a camera. Will opening your aperture for like ½ a second make the camera absorb enough light to get a clear picture of the moon? Probably yes.

Will doing the same with a far away galaxy be enough? Probably not. However, if you expose your camera to the galaxy’s light for a sufficiently long period of time, at some point enough light from it will gather up to give you a clear picture of it.

Edits – spelling and typos

>How do we get other pictures of far away galaxies that we can not see?

We don’t. If we cannot see them, we cannot take pictures of them. We only have pictures of galaxies we can see. Now, granted, by “see” I mean detect using the entire electromagnetic spectrum from radio waves through IR, visible light, UV, X-Rays, and Gamma waves.

What makes you think we can take pictures of galaxies we can’t see?

We (the human race) can see them. You can’t, because your eyes aren’t good at seeing tiny points in space, but telescopes equipped with cameras that can focus on a point in space and track it while taking a long exposure picture of that point can pick up enough light over time to be able to create a full picture of a galaxy that’s far away.

Light is made of photons. Think of photons like golf balls being fired in every direction by stars very far away. Light works much like the golf balls, spreading out as they travel. This is why light gets dimmer the further away the source is, as the photons spread out and less hit your eyes. Eventually, there are so few photons hitting your eye that your retina can no longer detect them.

Telescopes work by gathering up a larger area of photons and then focusing them down so they’re concentrated enough to see. Think of this like a big funnel gathering up the golf balls and funneling them into a more narrow stream. To get images of far away galaxies, we have many telescopes gathering many, many photons and gathering them over an extended period. This is called “long exposure,” and it allows us to get much clearer pictures of objects that would otherwise be too dim to see clearly.