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Solon
2011-Mar-09, 03:48 AM
Hi, new user, and not an astronomer, so maybe a silly question.:lol:
I was discussing with a friend as to whether the stars would get brighter the higher you went in a balloon. He thought with less atmosphere to block the light, they would do. I thought the atmosphere probably is what makes the stars visible, as the atmosphere would diffuse the light, otherwise the stars would be too small to see.
I can not find any pictures of the stars taken from a balloon, and can not see a simple answer on the 'Net, so time to contact the experts, I thought.
I did come across an old item from 1961 that explained the advantages of balloon astronomy:
http://books.google.ca/books?id=1wkAAAAAMBAJ&pg=PA191&lpg=PA191&dq=balloon+astronomy+visible+stars&source=bl&ots=DQdhUybDIV&sig=G7KU-sWSZa56tprHg9DCgX63tvM&hl=en&ei=CCd1TfSYOYG0sAPY_PG2Cw&sa=X&oi=book_result&ct=result&resnum=7&ved=0CC4Q6AEwBjgK#v=onepage&q=balloon%20astronomy%20visible%20stars&f=false

danscope
2011-Mar-09, 04:43 AM
Hi, The apparent size of the stars will not change. It is the properties of the atmosphere which become less as you go higher in altitude. But ...... you want a stable platform in order to do any serious astronomy. There are more than a few reasons why using a balloon may not be helpfull.

StupendousMan
2011-Mar-09, 01:19 PM
And there are more than a few reasons why using a balloon IS a good idea, for certain types of observations:


http://cmb.phys.cwru.edu/boomerang/
http://www.time.com/time/magazine/article/0,9171,810000,00.html
http://www.astronomy2009.org/globalprojects/specialprojects/blast/
http://www.nsf.gov/news/news_summ.jsp?cntn_id=103063

djellison
2011-Mar-09, 01:57 PM
I thought the atmosphere probably is what makes the stars visible, as the atmosphere would diffuse the light, otherwise the stars would be too small to see.

Think about that.... why do we send telescopes into space? Like Hubble, Spitzer, Kepler, WISE etc

It's because the atmosphere can wobble the image, and also block large parts of the EM Spectrum

Solon
2011-Mar-10, 12:28 AM
Think about that.... why do we send telescopes into space? Like Hubble, Spitzer, Kepler, WISE etc

It's because the atmosphere can wobble the image, and also block large parts of the EM Spectrum

Hi and thanks. I realise a lot of the EM spectrum is blocked by the atmosphere, so it helps to be above the atmosphere, but can the stars be seen by eye or with a camera from up there? I just can't find any images or mention of visible light astronomy from a balloon. As far as the space 'telescopes' go, they are filled with instruments, gratings, filters, I don't think they 'see' like a regular telescope, do they?

Hornblower
2011-Mar-10, 03:05 AM
Hi and thanks. I realise a lot of the EM spectrum is blocked by the atmosphere, so it helps to be above the atmosphere, but can the stars be seen by eye or with a camera from up there?
Yes indeed. Our astronauts can see them anytime they are not overpowered by solar glare. They are somewhat brighter than at sea level, because of the absence of dimming by the atmosphere.


I just can't find any images or mention of visible light astronomy from a balloon.
Perhaps few if any serious astronomers are bothering with observations from balloons.


As far as the space 'telescopes' go, they are filled with instruments, gratings, filters, I don't think they 'see' like a regular telescope, do they?They "see" much as we do with our eyes. The focused light excites electronic receptors in a way which is analogous to the action of light on the cones and rods in our retinas. What the modern imaging devices have that we do not are "brains" that can store incoming signals and build up the image intensity during a time exposure, which our brains cannot do. This is the case in telescopes on the ground as well as in space.

ngc3314
2011-Mar-10, 03:41 AM
Hi and thanks. I realise a lot of the EM spectrum is blocked by the atmosphere, so it helps to be above the atmosphere, but can the stars be seen by eye or with a camera from up there? I just can't find any images or mention of visible light astronomy from a balloon.

The Stratoscope II project in the 1960s used a 0.9m telescope beneath a high-altitude balloon to get extremely sharp images of Uranus and a few other things (I think the nucleus of the Seyfert galaxy NGC 4151 was observed more sharply than possible from the ground. IIRC, much later analysis of the scanned film showed that the rings of Uranus might just have been detected in front of the planet, though not well enough to be definitive if one didn't otherwise know they existed).

However, the ballooning niches have mostly been in far-IR/submillimeter (such as BLAST and many microwave-background experiments) and to some extent UV. Unlike optical work, for these there is no choice at all to getting above (most of) the atmosphere, so balloons have been important as a cheap alternative to orbit which will often do the job. There have been interesting adventures in chasing down and recovering instruments from some of these (one X-ray payload was found by a New Zealand fisherman months later).



As far as the space 'telescopes' go, they are filled with instruments, gratings, filters, I don't think they 'see' like a regular telescope, do they?

Just like a well-equipped telescope on the ground. In fact, for visible light, the instruments used on, for example, Hubble, are very similar in layout and detectors to those on the ground (albeit a lot lighter and with better backups).