Celestia Forums

1. I have a large flashlight that is 1 million candle power, and when i turn it on and point it at my other hand at the greatist distance my arms can allow, my hand warms up even though it's quite a bit away from the actual heat, thus begging the question, does the amount of light hitting an object affect it's tempurature, and would the same thing happen if I did it in a vacuum (ie, space)?

2. About one or 2 years ago, I wanted to see the surface of my Belle Hades planet in Terragen, so I did a little math with a calculator. Deneb is 260,000 times brighter than Sol. I divided that by the orbit of Belle hades in AU, which is 415 AU, meaning it is 415 times farther from the center of the star system than earth is from the center of the Solar system. The number i got was 626.5, meaning at that distance, Deneb is still 626 times brighter than the sun. Is that correct? (note: i gave belle hades an albedo of 0.55 because the clouds on that planet are pretty extensive and {especially the storm/hurricane clouds} are twice as thick {tall} as those on Earth.)

Yes and yes for the first one.

Lemme do the math for the other...

No. It comes out to like 1.5. You divide by the square of the distance in AU. Note, however, that a larger proportion of the planet's radiation is in UV and such nasties... not sure but I'm not thinking it's habitable worth a damn no matter what you do with the atmosphere...?

Thanks.




Umm... Any math experts here? I completely forgot how to do square roots.

To put a habitable planet around a bright star which emits lots of UV radiation I suggest you use a lagrange sunshade;

this device blocks all the direct radiation from the star and can be tuned to emit radiation at a lower frequency to provide light and heat for a trraformed planet.

I haven't made one yet, but the design would be fairly simple; a rotating opaque disk orbiting the L1 point,several hundred kilometers wider than the planet; on the side facing the planet a glowing disk emitting a beam of light at a suitable range of frequencies toward the planet (you could make this a stellar object defined by an .stc)

When I get round to it I'll make a range of such sunshades for the Orion's Arm project- the sunshade and mirror for the planet Kirch is one design to consider
http://www.nada.kth.se/~asa/bilder/terratech.gif

And another design is the Lagrange Magshield, a device used to protect planets from solar wind
http://www.orionsarm.com/tech/magshield_bowshock.jpg

I found this:
http://en.wikipedia.org/wiki/Photometry_%28optics%29

PlutonianEmpire wrote:2. About one or 2 years ago, I wanted to see the surface of my Belle Hades planet in Terragen, so I did a little math with a calculator. Deneb is 260,000 times brighter than Sol. I divided that by the orbit of Belle hades in AU, which is 415 AU, meaning it is 415 times farther from the center of the star system than earth is from the center of the Solar system. The number i got was 626.5, meaning at that distance, Deneb is still 626 times brighter than the sun. Is that correct? (note: i gave belle hades an albedo of 0.55 because the clouds on that planet are pretty extensive and {especially the storm/hurricane clouds} are twice as thick {tall} as those on Earth.)

If you go four times from the sun as earth, you receive 1/16 (1/(4 squared)) the sunlight. Go 10 times further, you get 1/100th the sunlight. If you go 415 times further away, you get 1/172225th the sunlight.

However, your sun here is 260,000 times brighter than the sun. So you'd get that multiplied by the fraction above, which is 1.51 times the sunlight that earth gets.

But you need to think aboutwhat wavelength that is etc too.