Astronomy pictures?

Question

I am really into astronomy but i always wondered how they get the pictures they have. Some are infered and are horrible pixilated pictures that are just dull then they have some blurry pictures of stuff in our solar system. Then they have amazing pictures that are just crazy! Like star clusters, nubulas, galaxies.... but then we d
on't have very many images of pluto...

-How do they get pictures of galaxies and thousands of stars?
-Why can't they get a great picture of neptune or pluto if they can of galaxies?
-Are most pictures just digitaly made
-Are they pieced together?

Please write somewhere in your answer if you have any prior knowlege about astronomy or are educated in it. I don't mind input i just don't want to be told something thats completely off and an un-educated guess

I understand hubble can take pictures, i just don't no what else does.....and again why can't the hubble get pictures of close up like pluto! and how do we have a picture of ourselves????!!?!? (milky way)

Answer 1

No, most pictures aren´t digitally made. They may be composited out of several images taken of several parts of the spectrum, their colors enhanced and so on but most pictures are real.

Galaxies are huge. Planets are tiny. The Andromeda galaxy takes up about twice as much sky as the moon. So do many nebulae while Pluto is incredibly tiny. It (and Neptune) remains a tiny speck of light even through the Hubble.
http://antwrp.gsfc.nasa.gov/apod/ap960507.html
http://antwrp.gsfc.nasa.gov/apod/ap971228.html
The only reason you cant see most nebulae and galaxies is because of your eyes poor light gathering abilities. Our eyes are set to see motion so evey image is "washed away" so we can see changes in our surroundings. Cameras, however, can be set to "see" for very long periods of time. You simply open the shutter for a very long time and leave it (which is why astrophotogrphy can be very boring). The cameras CCD (usually) then gathers light over all that time, "concentrating" it. And the huge yet faint objects in the night sky begin to appear. And also thousands upon thousands of stars (you would be amazed by what would suddenly become visible with just a $10 pair of binoculars). We can´t really do the same with Pluto as it is so tiny and emits so little light. It doesn´t matter how long you leave the shutter open. Pluto doesn´t get bigger. Too long exposure time and background stars will instead overload the cameras CCD. And you get no picture at all. To see Pluto well we really need to go there. And there is a probe on its way as we speak.


As for the Milky Way we can only see a small part of it. From our vantage point most of it is obscured by dust. But as the Milky Way covers the entire sky all we need to do is take a series of wide angle photos of the entire night sky throughout the whole year. The images are then stitched together digitally. The shape of our galaxy then becomes apparent. Like so:
http://antwrp.gsfc.nasa.gov/apod/ap051004.html
We can get a similar estimate of what a forest looks like even when we are inside it as we can compare it with other forests.
Compare with this:
http://antwrp.gsfc.nasa.gov/apod/ap040409.html

Answer 2

Most images that you see of deep space or nebulas are very long exposure photographs. As a result the pictures will show the nebula quite differently from how it appears to your eye if you are looking through a telescope.

In addition to this, most of the really good ones you see are actually several pictures "stacked" on top of each other to bring out greater detail.

The reason people don't get very good pictures of Pluto is simply because of its distance from the Earth (along with its small size). It is just too far away to be able to resolve any detail.

Answer 3

>>How do they get pictures of galaxies and thousands of stars?<<

Basically with standard photographic equipment, either film or digital. Long exposure allows images of faint objects like stars and galaxies that are not visible to the unaided eye.

>>Why can't they get a great picture of neptune or pluto if they can of galaxies?<<

Neptune and Pluto are close but tiny, while galaxies are much more distant but also much MUCH larger. If you do the relevant trigonometry, you find that even the most distant galaxy appears bigger than pluto does from here. In fact, many galaxies and nebulae actually appear larger than the full Moon from here, but are too faint to be visible to the naked eye.

>>Are most pictures just digitaly made<<

These days quite often they are, but many images were captured on simple photographic film.

>>Are they pieced together?<<

Some of them are, but not all.

Answer 4

Rewording your main question as I understand it:
We have many nice pictures of distant nebulae and galaxies - why is it that we do not have detailed and nice looking pictures of Neptune and Pluto? They are much closer to us. Are the pictures the more distant objects artificially constructed with digital models?

I like to answer it in an illustrative way. Think of Neptune and Pluto as the screw holding the strobe light on top of the antenna tower three miles from you. Then think of a nebula within our milky way as a row of peaks on a mountain range 50 miles away as seen on an exceptionally clear day.
Now you come as an amateur photographer with a nice digital SLR camera and telephoto lenses you bought for 2000 USD. You are told to take two pictures of distant objects to prove two things - first you are a good photographer - and secondly your equipment is worth its money. You are told to take a picture of the distant mountain range and also a picture of that screw holding the strobe light on top of the TV transmission tower in your vicinity.

You can surely impress people with the picture of the mountain range where the individual peaks can be identified and show detail of light and shade in snow and gravel. But your picture of that screw will be so disappointing - because with the longest telephoto lens you get the upper half of the tower filling the span of our picture. The strobe light has probably a dimension of less than a dozen pixels. Looking for the screw will show you a size of less than one pixel.

The answer to your question lies in the "apparent angle". A nebula in the night sky can have an angular size of half a degree up to several degrees (like the distant mountain range). While a planet that is much less distant has an angular size of a few seconds of arc or even less. (1 thousandth of a degree to 1 ten thousandth of a degree)
Your mountain range or nebula is painted across thousands of pixels in your camera - while the screw on the tower or Pluto is shown on one pixel or smaller.

I hope this helps to understand the basics.
I did some astrophotography with a simple (non-SLR) 4megapixel camera: http://www.pbase.com/es839145/canon_g2_astro

Answer 5

Nowadays most astrophotos are digital. Some are pieced together, if it's a wide field (like a large nebula), but most are single frame. That also explains why some astrophotos look pixellated: they are. With large fields, this is no big deal, but if you're looking at something quite small, the pixels become noticeable. So if you're photographing something very small, chemical film is still the best choice.

Most astronomical objects are quite dim, and require exposures of long times, occasionally very long exposure times (like hours). That's why it's hard to get really good photos of planets: they move.

Answer 6

For good pictures, you need a huge, expensive telescope on a mountain top or satellite, and hours of exposure time. If you haven't got $millions to spend on it, don't expect to get spectacular pix.

Also, many of the pictures that you see on the internet are computer generated from data, and they don't look anything like the actual images seen in telescopes.

Answer 7

The dwindled Blue Dot is fantastic, i assume. yet Carl Sagan tried to steer us through our sentiments to the incorrect end. He pronounced: "The Earth is the only international commonly used so a the thank you to harbor existence. there is nowhere else, a minimum of interior the close to destiny, to which our species ought to migrate. bypass to, definite. Settle, not yet. like it or not, for the 2nd the Earth is the place we make our stand. it is been pronounced that astronomy is a humbling and character-development journey. there is possibly no extra desirable demonstration of the folly of human conceits than this distant image of our tiny international. To me, it underscores our accountability to deal extra kindly with one yet another, and to maintain and cherish the dwindled blue dot, the only living house we've ever commonly used." incorrect. the image would not illustrate our unimportance. extremely, it underscores our planet's loss of ingredients, the urgency of turning out to be use of what right here as a bridge to gaining the ingredients of the entire image voltaic equipment, and the corollary crucial of combating any competing objective from shifting into our way. First conflict, to do away with rival breeds, to trim down and purify our race as a results of fact the device of cosmic ambition that it would be, and then use the terrestrial grant of fossil fuels to unencumber the sky and carry the seed of Earth's existence to everywhere else it could take root. Carl Sagan listened to leftist propaganda too long. Or he listened to that Coca Cola track some circumstances too many. Or he substitute right into a cunning fellow who knew extra desirable and had unstated reasons for enjoying on our humanitarian sentiments.

Answer 8

The amazing pics u r talking about can only come from one thing, the Hubble Telescope. This telescope takes amazing pics. Go to google and type in Hubble Telescope and you can learn more about it!

Answer 9

Try a search for "astrophotography". Check out some of the introductory books, especially where they talk about resolution and optics.