# Space probe imagery - why not in the visible spectrum?

**URL:** <https://boards.straightdope.com/t/space-probe-imagery-why-not-in-the-visible-spectrum/178200>\
**Category:** Factual Questions\
**Created:** [May 29, 2003, 5:25am UTC](https://boards.straightdope.com/t/space-probe-imagery-why-not-in-the-visible-spectrum/178200 "2003-05-29T05:25:13Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Engywook](https://avatars.discourse-cdn.com/v4/letter/e/bc8723/32.png) [@Engywook](https://boards.straightdope.com/u/Engywook)\
**Post date:** [May 29, 2003, 5:25am UTC](https://boards.straightdope.com/t/space-probe-imagery-why-not-in-the-visible-spectrum/178200/1 "2003-05-29T05:25:13Z")

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There was a very profoundly beautiful photograph of the earth, taken from Mars orbit, shown here:

[http://www.msss.com/mars\_images/moc/2003/05/22/](http://www.msss.com/mars_images/moc/2003/05/22/)

As usual, though, it’s color enhanced. This got me to wondering: why are most (if not all?) images taken from space probe grayscale, infrared, or something other than a color photograph in our visual slice of the EM spectrum?

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**Author:** ![Bob55](https://avatars.discourse-cdn.com/v4/letter/b/e9c0ed/32.png) [@Bob55](https://boards.straightdope.com/u/Bob55)\
**Post date:** [May 29, 2003, 5:36am UTC](https://boards.straightdope.com/t/space-probe-imagery-why-not-in-the-visible-spectrum/178200/2 "2003-05-29T05:36:51Z")

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IIRC light in the visual range is absorbed by interstellar particles. Xrays and infrared are more penetrating. There’s something called the [water hole](http://www.setileague.org/general/waterhol.htm), and this site also says:

> [@](#):
>
> Low frequencies are plagued by galactic noise, primarily due to synchrotron radiation (charged particles spiraling through our Sun’s and our planet’s magnetic fields). High frequencies are subject to quantum-effect emissions

There’s a nice graph at that link, and Google will turn up a lot more.