What do the colours in pictures taken with the Hubble telescope represent?

Question

In pictures such as http://www.spacetelescope.org/images/archive/top100/

There are a lot of amazing colours, I'm wondering if they are natural.

Answer 1

What interests astronomers is a color range wider than what humans can see. There are both infrared and ultraviolet frequencies that are important in determining the composition of gases, the ages of stars, and the temperatures of gases. Some of these pictures have various colors we can't see and the astronomers have changed their colors so that they can be seen. In other words a wider spectrum of colors is compressed so that we can see all the variation, but in so doing, the colors aren't natural.



The above is a collection of general statements but in the website you post, if you click on each individual picture, there is usually an explanation of the colors and a bit about why they are done that way.

Answer 2

The imagers on HST are (essentially) just like the digital camera in your cell phone. They both are based on a charge-coupled device (CCD), which is behind a shutter. The main difference is, between the CCD in HST there is a piece of colored glass (often called a "filter"), which only permits certain wavelengths (or frequencies) of light to pass through. Whereas, your digital camera doesn't have a filter in the same way. So the images from HST (or any other professional telescope) are inherently black-and-white, but we use computer software (and knowledge of which filter was used) to combine a host of B&W images to (through individual filters) to create a false-color image. So, the colors you see there depend on which filters were used and in way they (ie. the digital artist who combined the B&W images to a false-color) used them.



Usually, the artists will put a "blue" image, "green" and "red" image in such a way that things which are intrinsically hotter or higher energy are in the blue "channel" -- but not always. This issue can be seriously confounded by the possibility of "narrow-band" filters which can isolate a very narrow or specific wavelength.



Ultimately, the colors here were chosen and displayed to impress and awe you. It sounds like it worked. Now, if you go to the hubble site you can get more information as to which filters were used and in what way. Unfortunately, these images donot have that information, so there is no real answer.

Answer 3

I work with the Hubble Space Telescope, and there is no short answer to your question.



The imagers on HST are (essentially) just like the digital camera in your cell phone. They both are based on a charge-coupled device (CCD), which is behind a shutter. The main difference is, between the CCD in HST there is a piece of colored glass (often called a "filter"), which only permits certain wavelengths (or frequencies) of light to pass through. Whereas, your digital camera doesn't have a filter in the same way. So the images from HST (or any other professional telescope) are inherently black-and-white, but we use computer software (and knowledge of which filter was used) to combine a host of B&W images to (through individual filters) to create a false-color image. So, the colors you see there depend on which filters were used and in way they (ie. the digital artist who combined the B&W images to a false-color) used them.



Usually, the artists will put a "blue" image, "green" and "red" image in such a way that things which are intrinsically hotter or higher energy are in the blue "channel" -- but not always. This issue can be seriously confounded by the possibility of "narrow-band" filters which can isolate a very narrow or specific wavelength.



Ultimately, the colors here were chosen and displayed to impress and awe you. It sounds like it worked. Now, if you go to the hubble site you can get more information as to which filters were used and in what way. Unfortunately, these images donot have that information, so there is no real answer.



http://hubblesite.org/newscenter/



Best of Luck!!



PS, Click on the "Fast Facts" from the hubblesite.org on an image you like. There, they will list the filters and a few other useful details on how to interpret the colors.

Answer 4

The colors are real. However, it's more color than you would be able to see with your own eyes because our eyes are not sensitive enough to see color in dim objects, such as nebulas. Photos taken by telescopes use time exposures to gather more light in order to bring out the color. In most astro photos the color is further enhanced by taking three exposures using a red, green, and blue filter, and then combining them. But they're not false colors, they're just presented in greater purity by removing the bleeding of one color into another.

Answer 5

Sometimes they're reasonably close to reality, other times they're false colours. Images of nebulae in particular often use the hydrogen alpha wavelength, a very deep red shade humans don't naturally see all that well but, as red.

Answer 6

no color camera is sensitive enough to take color pictures of stars etc so a B/W camera is used with different filters in front , as this also reduces the amount of light getting to the camera all photos of stars, nebulae etc are fake as they are artificially enhanced by combining the different pictures