light pollution

tclifford · Post by **tclifford** » Thu Apr 19, 2007 7:58 am

If you lived in the middle of a star cluster would it be daytime, all the time? so would you even be aware of 'the universe'...

craterchains · Post by **craterchains** » Thu Apr 19, 2007 11:59 am

Now THAT would be light polution.

NoelC · Post by **NoelC** » Thu Apr 19, 2007 4:39 pm

I read something somewhere once that described what the night sky inside a globular cluster, such as M13, would be like... They stated that the sky would be full of bright stars, like a whole bunch of Siriuss and Vegas, as the stars are still light-years apart.

It sure seems like it would be pretty spectacular, though.

-Noel

AZJames · Post by **AZJames** » Sun Apr 22, 2007 5:52 am

It is likely that the night sky on a planet orbiting a star in a globular cluster would be pretty spectacular because of the clarity. There would be very little interstellar dust and gas to impede your view. But as to the light pollution question; don't forget that stars would be separated by vast distances. So you can probably forget about reading your newspaper from just starlight.

The most extraordinary sight, however, would be the 'nearby' galaxy. It would be like that scene near the end of the movie, Star Wars, where a spiral galaxy takes up much of night sky.

astro_uk · Post by **astro_uk** » Sun Apr 22, 2007 9:58 am

The most extraordinary sight, however, would be the 'nearby' galaxy. It would be like that scene near the end of the movie, Star Wars, where a spiral galaxy takes up much of night sky.

It really wouldn't be that impressive, your eyes aren't able to add up flux like a telescope CCD does, so the low surface brightness features would still remain invisible. You might see a bright blob in the centre and maybe a few knots of star formation but that would be about it without the aid of a telescope to increase the amount of light you see.

NoelC · Post by **NoelC** » Wed Apr 25, 2007 3:46 pm

Who's to say whether spacefarers won't evolve hugely sensitive eyes? Let's say thousands of generations of lives pass on a cosmic ark, and astronomy is somehow an important field to the inhabitants. Perhaps those who thrive will be those who see very well in near darkness.

Or there could be directed breeding.

-Noel

daedalus · Post by **daedalus** » Sun Sep 21, 2008 7:18 am

AZJames wrote:The most extraordinary sight, however, would be the 'nearby' galaxy. It would be like that scene near the end of the movie, Star Wars, where a spiral galaxy takes up much of night sky.

Umm... isn't that what our Milky Way does, and we can barely see it?

harry · Post by **harry** » Sun Sep 21, 2008 1:04 pm

G'day from the land of ozzzz

If your lucky you maybe part of a solar system of stars.

Imagine the chaos

makc · Post by **makc** » Sun Sep 21, 2008 4:40 pm

daedalus wrote:isn't that what our Milky Way does, and we can barely see it?

can be argued that it's because of dust in the disk obscuring the light of stars; should have less impact from outside.

BMAONE23 · Post by **BMAONE23** » Sun Sep 21, 2008 5:23 pm

I think it is more likely a matter of candlepower. Stars emit photons, the light we see, and the closer you are to the star the greater the apparent candlepower.

The sun gives out somewhere around 1.575 octillion candlepower at the surface

To someone on the Earth, at latitude 40 degrees or so, sunlight is about 250 Watts per square meter. A standard candle, at a distance of 1 meter, gives out 1/670 Watts per square meter.

So the sun is 250 x 670 = about 168,000 times brighter at earth.

A standard candle gives out about 1/53.3 = 0.01876 Watts.

By the time you get to Pluto, the sun is like a 40watt lightbulb.(photonic spread at work)

One foot-candle of light is the amount of light that a candle generates one foot away from the object receiving the photons.

A lumen is a way of measuring how much light gets to what you want to light! A LUMEN is equal to one foot-candle falling on one square foot of area.(photonic spread)

Light measured on an object is INVERSELY PROPORTIONAL to the distance the object is from the light source.

So the farther away from the light source you are, the dimmer it appears until, in the case of light traveling from tens of thousands of light years away, the photons have spread out so much that your eyes can't register the light before the image is refreshed in your mind. approx 1/30th of a second is all the time your eyes give you to gather light.

harry · Post by **harry** » Mon Sep 22, 2008 6:23 am

G'day BMAone23

So that means we need to take our own light when we go to Pluto and make our own moonshine.

I could not think of anything else, brain dead, I have the flu.

neufer · Post by **neufer** » Mon Sep 22, 2008 4:41 pm

tclifford wrote:If you lived in the middle of a star cluster would it be daytime, all the time? so would you even be aware of 'the universe'...

It would probably be equivalent to full moon light all of the time.

Doum · Post by **Doum** » Mon Sep 22, 2008 5:03 pm

Look at this. It's a polemic but it might help to visualise.

http://antwrp.gsfc.nasa.gov/apod/ap080906.html

Nahh it aint mean, the joke to put it there was to big a temptation to try to resist it and it is in someway a pertinent apod picture.

Starship Asterisk*

light pollution

light pollution

Re: light pollution