ASTRONOMY PICTURE OF THE DAY
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ASTRONOMY PICTURE OF THE DAY
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 William Rothamel  Send message Joined: 25 Oct 06 Posts: 3756 Credit: 1,999,735 RAC: 4 
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Very nice. As I have ranted before in these forums there just aren't that many main sequence, non binary stars within 100 and even 1000 light years from Earth. Take a look at the zoom-in presentations here and you will see that this is so. Sort of suggests that if we expect to detect ET's by eavesdropping, then we need to concentrate on the Alpha Centauri group and any other stars( especially those who apparently have planets) that are as close as possible to Earth. |
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Jim1348 Send message Joined: 13 Dec 01 Posts: 212 Credit: 520,150 RAC: 0
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Sort of suggests that if we expect to detect ET's by eavesdropping, then we need to concentrate on the Alpha Centauri group and any other stars( especially those who apparently have planets) that are as close as possible to Earth. Very true, except that if evolution has to jump through as many hoops as it did on earth to get to intelligent life (and we don't know of a better way), then there won't be enough planets close by that might have ET. Unless SETI gets access to much better radio-telescopes (e.g., Square Kilometer Array at least), I don't think there is any real hope. |
rob smith    Send message Joined: 7 Mar 03 Posts: 22202 Credit: 416,307,556 RAC: 380 
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Given that SETI@Home is already using two of the most powerful radio telescopes in the world there wouldn't be much of a gain getting data from the SQA when compared to the Southern-sky view gained from Parkes. Bob Smith Member of Seti PIPPS (Pluto is a Planet Protest Society) Somewhere in the (un)known Universe? |
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Jim1348 Send message Joined: 13 Dec 01 Posts: 212 Credit: 520,150 RAC: 0
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With a lot of luck, we might be able to see out 10 light years with the current radio-telescopes, and a cooperative advanced civilization willing to send a powerful radar signal in our direction once in a while. But if there are only a few thousand advanced civilizations in the Milky Way at any given time, their mean distance is something on the order of 1000 light years. Our current stuff is not enough, except for wasting a lot of power. |
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rob smith Send message Joined: 7 Mar 03 Posts: 22202 Credit: 416,307,556 RAC: 380
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The distance you quote is "rather pessimistic" - given that we are currently analyzing data for potential signals that is coming from thousands of light years away. It is highly improbable that we will ever be able to "decode" a signal for many reasons other than "lack of signal strength" unless we can find the RF equivalent of the "Rosetta Stone" to help us on the way. Bob Smith Member of Seti PIPPS (Pluto is a Planet Protest Society) Somewhere in the (un)known Universe? |
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Jim1348 Send message Joined: 13 Dec 01 Posts: 212 Credit: 520,150 RAC: 0
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The distance you quote is "rather pessimistic" - given that we are currently analyzing data for potential signals that is coming from thousands of light years away. It is highly improbable that we will ever be able to "decode" a signal for many reasons other than "lack of signal strength" unless we can find the RF equivalent of the "Rosetta Stone" to help us on the way. I assume you are one of the more knowledgeable people on this forum concerning the subject of radio propagation. But I am not convinced that you have ever heard of "RSL" (received signal level), or "path loss", or "antenna gain". But most importantly, you do not seem to recognize the difference in power levels from an intelligent civilization and from natural phenomena, such as exploding stars, gas clouds, accretion discs, etc. It is the latter that the current generation of radio-telescopes was constructed to find. They have no hope with the former. But you are right there are other reasons. Any advanced civilization will use data compression, encryption, and who knows what else. We have just been doing radio for 100 years; they will have been doing it for thousands, if not millions on average. Who knows what that will look like? |
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William Rothamel Send message Joined: 25 Oct 06 Posts: 3756 Credit: 1,999,735 RAC: 4
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If I may weigh in here. We do not need to fret too much about received power levels of intended --"we are here" type of transmissions.--they would be narrow band, high power and have a non-Gaussian spectrum. The message would most probably contain a "Preamble" to indicate that it is from a sentient society. Probably this could take the form of counting out the first ten numbers, the fist 50 primes and/or the first 50 digits of Pi. This could be as simple as on-off with a marker between digits of time or some other repeated signal. Next I would expect a video raster perhaps itself having a preamble of length by width. The encoding could be simple or more complex--If it could be decoded it might show pictures of the aliens and their cities as well as a primer for numbers and perhaps sounds--maybe a phoneme with the matching alphabetic characters to describe simple objects. Lastly might be a star map to locate the civilization in reference to some celestial formations that we might be able to figure out. If we ever found such a signal I think that we would know that maybe 30,000 years ago there was an advanced civilization at a particular location in the cosmos. We could reply and hope that in 60,000 years we would get an acknowledgement. |
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Jim1348 Send message Joined: 13 Dec 01 Posts: 212 Credit: 520,150 RAC: 0
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We do not need to fret too much about received power levels of intended --"we are here" type of transmissions.--they would be narrow band, high power and have a non-Gaussian spectrum. Are we sending out such a signal? Why would we? We may not make it another 100 years as an advanced society, let alone thousands. And the other advanced civilizations would have to make it that far too, in order to send (or receive) such a signal. |
Pierre A Renaud  Send message Joined: 3 Apr 99 Posts: 998 Credit: 9,101,544 RAC: 65 
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Which is a shame, really: even amidst a government shutdown, unpaid heroes keep feeding the astounding Astronomy Picture of the Day Archive at https://apod.nasa.gov/apod/archivepix.html Haven't popped in here for a while. No Astromomy pictures of the day to be seen much?    Apr 3, 1999 - May 3, 2020
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Gordon Lowe  Send message Joined: 5 Nov 00 Posts: 12094 Credit: 6,317,865 RAC: 0
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I love APOD. It's been my default homepage for many moons.  The mind is a weird and mysterious place
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Pierre A Renaud Send message Joined: 3 Apr 99 Posts: 998 Credit: 9,101,544 RAC: 65
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Bump -- Astronomy Picture of the Day Archive https://apod.nasa.gov/apod/archivepix.html Pictures from Space - Satellite Images - Image of the Day | Space https://www.space.com/34-image-day.html Today's Image | EarthSky https://earthsky.org/todays-image Space in Images - Sets - Space Science image of the week http://www.esa.int/spaceinimages/Sets/Space_Science_image_of_the_week Space Photos Of The Week | Latest News, Photos & Videos | WIRED https://www.wired.com/tag/space-photos-of-the-week/ HiRISE | New Captioned Images https://www.uahirise.org/updates/ -- Amazing Images: The Best Science Photos of the Week | Live Science https://www.livescience.com/50717-amazing-images.html Image of the Day Articles | The Scientist Magazine® https://www.the-scientist.com/image-of-the-day Pictures of the Day - Science360 News Service | National Science Foundation https://news.science360.gov/files/pic-day/ EPOD - Earth Science Picture of the Day - a service of USRA https://epod.usra.edu/blog/ Sci Candy Archives - Science Friday https://www.sciencefriday.com/series/sci-candy/ Photo of the Day Archive https://www.nationalgeographic.com/photography/photo-of-the-day/archive/ Photo of the Day | Smithsonian https://www.smithsonianmag.com/category/photo-of-the-day/ Apr 3, 1999 - May 3, 2020
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ML1 Send message Joined: 25 Nov 01 Posts: 20289 Credit: 7,508,002 RAC: 20
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Making all the live links clickable: Bump Enjoy! Keep searchin' Martin See new freedom: Mageia Linux Take a look for yourself: Linux Format The Future is what We all make IT (GPLv3) |
Misfit  Send message Joined: 21 Jun 01 Posts: 21804 Credit: 2,815,091 RAC: 0
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