quite possibly the most random ever posted by a noob

[RobDevlin]

hi guys and girls

this is my first post and i need a little help. I'm currently rechcing a short story baised around the WOW signal and need to know something about the technical side.

how long would radio waves take to get from Sagittarius to, say the jodrell bank obseritory?

thanks in advance

[Jeff RV]

Sagittarius is a constellation, so the stars & galaxy's etc in it are at various distances from approx 400 to over well over 1000 years away at the speed of light = 186,000 miles per second approx.

I'm sure someone on here will answer this in a more scientific and accurate manner for you.

Hope this helps

Jeff.

[scotastro]

Just beat me to it there

More difficult to answer than you probably realise. The reason is that the stars that make up Sagittarius are just a random collection that the ancients gave a name to. They are not at the same distance. For example the stars that make up the "teapot" part vary between 77 and 306 light years. One star (Mu Sag) is mag +3 but 29,650 light years.

All the constellations are 3 dimentional, not like the representation on a piece of paper.

If you name a particular star I might be able to give its distance.

Mike

[Jeff RV]

That's what i meant to say.

Jeff.

[barkis]

As a closer to home example. It takes just over 8 minutes for the suns light to reach the earth.

Therefore, when you see the last part of the sun dip below the horizon when setting, it actually completed the act 8 minutes earlier.+ a few seconds.

[Doc]

Just took this from another web site hope it helps.

Radio waves, like all forms of electromagnetic waves, travel at the speed of light. Unlike the speed of sound that changes depending on the substance through which the sound wave travels, the speed of light is a constant. The speed of light has been measured to be about 9.836 x 10⁸ ft/s (2.998 x 10⁸ m/s) or 186,200 miles per second. Speed is defined as a change in distance over time.

Given a known distance, we can rearrange this relationship to solve for the time it takes to travel that distance at a certain speed.

The average distance between the Earth and Moon is about 239,000 miles (384,600 km). Plugging this value and the speed of light into the above equation allows us to solve for the time it takes for radio waves to travel between the Moon and Earth, as shown below.

[/td]

Distance from Earth & One-Way Communication Time at 5 PM on 11 December 2005

Object

Distance* [miles]

Distance* [km]

Distance*

Time

Moon	233 thousand	375 thousand	58.8 ER	1.25 seconds
Venus	36.4 million	58.6 million	0.392 AU	3.26 minutes
Mars	57.5 million	92.6 million	0.619 AU	5.15 minutes
Sun	91.6 million	147.4 million	0.985 AU	8.19 minutes
Mercury	92.4 million	149 million	0.994 AU	8.27 minutes
Jupiter	572 million	921 million	6.159 AU	51.22 minutes
Saturn	786 million	1.26 billion	8.454 AU	1.17 hours
Uranus	1.88 billion	3.03 billion	20.266 AU	2.81 hours
Neptune	2.84 billion	4.58 billion	30.603 AU	4.24 hours
Pluto	2.98 billion	4.79 billion	32.017 AU	4.44 hours
Proxima Centauri (closest star to Sun)	24 trillion	40 trillion	4.2 ly	4.2 years
Sirius (brightest star in night sky)	51 trillion	82 trillion	8.7 ly	8.7 years
Aldebaran (brightest star in Taurus)	353 trillion	568 trillion	60 ly	60 years
Regulus (brightest star in Leo)	406 trillion	653 trillion	69 ly	69 years
Spica (brightest star in Virgo)	1.3 quadrillion	2.1 quadrillion	220 ly	220 years
Rigel (brightest star in Orion)	8.2 quadrillion	13 quadrillion	1400 ly	1400 years
Andromeda (closest galaxy to Milky Way)	17 quintillion	27 quintillion	2.9 million ly	2.9 million years

[David Galvin]

I do not need to repeat the previous replies but would recommend watching the film Contact starring Jodie Foster. The film is adapted from the novel by Carl Sagen and appears to be scientifically accurate even giving the R.A and Dec of Vega correctly. :shock:

http://en.wikipedia.org/wiki/Contact_(movie)

Also check out Phil Plait's excellent website at http://www.badastronomy.com/bad/movies/contact.html

for a review of Contact

[RobDevlin]

thjanks to eveyone for the brilliant info, its been utterly invalueable. you guys rock

[legion48]

Just took this from another web site hope it helps.

Radio waves, like all forms of electromagnetic waves, travel at the speed of light. Unlike the speed of sound that changes depending on the substance through which the sound wave travels, the speed of light is a constant. The speed of light has been measured to be about 9.836 x 10⁸ ft/s (2.998 x 10⁸ m/s) or 186,200 miles per second. Speed is defined as a change in distance over time.

The speed of light does change depending on what it's passing through. In water, for instance, it's 140,000 Miles per second.

[barkis]

I have to agree with you David. Contact was a great film, and I enjoyed it immensely.

Carl Sagan to me epitomised the Universe. His Cosmos series was incredibly addictive for me, and I don't believe anyone else but him, could have made it the inspiring series it was.

Ron.

[RobH]

Don't just watch the film 'Contact'....read the book. There's a whole extra layer to it regarding 'Pi' that didn't make it into the film....fabulous book by an amazing human being.

His book systematically taking apart various modern superstitions, 'The demon Haunted World', is also rather good....unless you happen to think you've been kidnapped by ET etc :D

Cheers

Rob

[Jeff RV]

I have to agree with you David. Contact was a great film, and I enjoyed it immensely.

Carl Sagan to me epitomised the Universe. His Cosmos series was incredibly addictive for me, and I don't believe anyone else but him, could have made it the inspiring series it was.

Ron.

I've got to agree with you there Ron, The Cosmos series was mesmerizing, I think it was so successful because of his sheer simplicity in the explanation of things (Even i could understand it) All available on YouTube.

http://www.youtube.com/watch?v=myPSkL_S45E

Jeff.

[Periscope]

I have just received a text from someone on a planet orbiting Aldebaron wishing me a Happy first birthday. :laughing2: :laughing2: :laughing2:

I found Doc's chart quite informative, regarding the times that would be needed to make contact with anyone, should there be life out there.

Geoff

[Psychobilly]

Jeff Thanks for the Cosmos link on you tube...

Soemthing else to pass the time with now...

Billy...