Joined: Dec 22 2001 Posts: 31966 Location: The Corridor of Uncertainty
Someone told me all the Hubble pictures are in black and white and the colour is added later by NASA using their interpretations of what is being viewed. Is that right?
"If you start listening to the fans it won't be long before you're sitting with them," - Wayne Bennett.
Joined: Feb 17 2002 Posts: 28357 Location: MACS0647-JD
Bullseye wrote:Someone told me all the Hubble pictures are in black and white and the colour is added later by NASA using their interpretations of what is being viewed. Is that right?
Yes and no. Hubble doesn't have a "colour camera", all images are taken in grayscale.
Many images are published showing either false, or partly false colours (compared to what you might see with your own peepers if you could) but never without explaining what has been done, and usually to illustrate specific things.
However, Hubble can and does produce amazing "natural colour" images. The basic way to do this is to take images through red, green and blue filters. Then combine the results. So the shot through the red filter only lets through the red part of the visible light spectrum; so you know that that image is actually just the shades of red; same for green, same for blue. Combine them and hey presto, full colour! http://hubblesite.org/gallery/behind_th ... /index.php
As for "interpretation", it's all a question of degree. For example, a picture of the Crab nebula may look lovely and colourful, and the light and colours recorded are genuine and "real". Yet you would never experience it like that, as the image is compressed light that actually may have taken a powerful telescope hours to gather. If you were in space looking at it, it would be extremely faint and not very colourful at all.
To qualify the basic answer, Hubble has various cameras including the Wide Field Camera 3 (WFC3) which sees near-ultraviolet, visible and near-infrared; the Cosmic Origins Spectrograph (COS), a spectrograph that sees exclusively in ultraviolet light; the Space Telescope Imaging Spectrograph (STIS), a spectrograph that sees ultraviolet, visible and near-infrared light; and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) which essentially sees heat not light, if I can put it that way (it's all just different parts of the spectrum). As you can see, an infrared image HAS to be given "false colours" since we can't see infrared, or much UV, and so they have to interpret these images into visible light images so we have an impression of what Hubble sees. Same for images from X-ray telescopes, or Radio telescopes.
Bullseye wrote:Someone told me all the Hubble pictures are in black and white and the colour is added later by NASA using their interpretations of what is being viewed. Is that right?
Yes and no. Hubble doesn't have a "colour camera", all images are taken in grayscale.
Many images are published showing either false, or partly false colours (compared to what you might see with your own peepers if you could) but never without explaining what has been done, and usually to illustrate specific things.
However, Hubble can and does produce amazing "natural colour" images. The basic way to do this is to take images through red, green and blue filters. Then combine the results. So the shot through the red filter only lets through the red part of the visible light spectrum; so you know that that image is actually just the shades of red; same for green, same for blue. Combine them and hey presto, full colour! http://hubblesite.org/gallery/behind_th ... /index.php
As for "interpretation", it's all a question of degree. For example, a picture of the Crab nebula may look lovely and colourful, and the light and colours recorded are genuine and "real". Yet you would never experience it like that, as the image is compressed light that actually may have taken a powerful telescope hours to gather. If you were in space looking at it, it would be extremely faint and not very colourful at all.
To qualify the basic answer, Hubble has various cameras including the Wide Field Camera 3 (WFC3) which sees near-ultraviolet, visible and near-infrared; the Cosmic Origins Spectrograph (COS), a spectrograph that sees exclusively in ultraviolet light; the Space Telescope Imaging Spectrograph (STIS), a spectrograph that sees ultraviolet, visible and near-infrared light; and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) which essentially sees heat not light, if I can put it that way (it's all just different parts of the spectrum). As you can see, an infrared image HAS to be given "false colours" since we can't see infrared, or much UV, and so they have to interpret these images into visible light images so we have an impression of what Hubble sees. Same for images from X-ray telescopes, or Radio telescopes.
Last edited by Ferocious Aardvark on stardate Jun 26, 3013 11:27 am, edited 48,562,867,458,300,023 times in total
Joined: Dec 22 2001 Posts: 9721 Location: Cougarville
Just to keep the daily wail supporters on the edge of their paranoia.
The optics, sensors, resolution of Hubble are now , in digital terms, obsolete. Think about what Google earth can show you, and that is pretty low grade stuff to what the current satellites looking at the earth can see.
Just imagine what you thought was fun when looking at your house and then think about what can actually be seen.
Sleep tight.
regards
and ENJOY your sport
Leaguefan
"The Public wants what the Public gets" - Paul Weller
Joined: Feb 17 2002 Posts: 28357 Location: MACS0647-JD
Leaguefan wrote:The optics, sensors, resolution of Hubble are now , in digital terms, obsolete. Think about what Google earth can show you, and that is pretty low grade stuff to what the current satellites looking at the earth can see.
Hubble has some equipment 20 years old although a couple of cameras were installed just a few years back, but yes, obsolete in terms of what equivalent stuff could be built in two decades on, certainly NO in terms of what Hubble can do and see. Which is why it remains heavily oversubscribed.
Plus, Hubble doesn't suffer from atmospheric interference so apart from turbulence (which corrective optics can improve, but only for narrow fields of view) it has truly dark skies, compared with anywhere on Earth.
Plus, Much of the spectrum simply doesn't make it through the atmosphere so space-based cameras will always remain the only option for that task.
Oh - and there's no comparison at all with Earth mapping satellites - They are seeing objects at 500 miles or so. Hubble is seeing 13+ billion light years.
Finally can I assure Wail readers that if the authorities wanted to spy on your house, they would probably get better resolution images from a nearby parked van. They don't actually want to see your roof. They are after YOU and the views through your windows.
Last edited by Ferocious Aardvark on stardate Jun 26, 3013 11:27 am, edited 48,562,867,458,300,023 times in total
Joined: Feb 17 2002 Posts: 28357 Location: MACS0647-JD
Roundabout now, the Dawn spacecraft should just be entering an orbit around the asteroid, or dwarf planet, Ceres. Dawn was launched in 2007 and has an ion drive propulsion system. Over the next few months they will get the orbit down to a height of only a couple of hundred miles, but here is a view it took recently from around 29,000 miles. Incidentally they have no idea what the bright spots are, I am assuming it is the portal to the aliens' underground city.
Last edited by Ferocious Aardvark on stardate Jun 26, 3013 11:27 am, edited 48,562,867,458,300,023 times in total
Joined: Dec 22 2001 Posts: 27757 Location: In rocket surgery
More pics of Ceres
"Dawn scientists can now conclude that the intense brightness of the mysterious spots on #ceres is due to the reflection of sunlight by highly reflective material on the surface, possibly ice," Christopher Russell, principal investigator for the Dawn mission, said recently.
"Dawn scientists can now conclude that the intense brightness of the mysterious spots on #ceres is due to the reflection of sunlight by highly reflective material on the surface, possibly ice," Christopher Russell, principal investigator for the Dawn mission, said recently.
Joined: Feb 17 2002 Posts: 28357 Location: MACS0647-JD
It's as I thought. There is no such thing as reality. If you have a bit of spare time to digest a thought-provoking proof, then get your thinking gear around this analysis of what happens to you if you fall into a massive black hole
It's as I thought. There is no such thing as reality. If you have a bit of spare time to digest a thought-provoking proof, then get your thinking gear around this analysis of what happens to you if you fall into a massive black hole
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