View Full Version : How would different stars look on different planet

2003-Nov-07, 03:15 PM
Good Day!

I happened upon a topic by Tinaa on Designing Your Own Planet in the Everything Else category (by the way, how did that go?) and it sort of broached something I was wondering about. In responding, Planetwatcher mentioned that the sky on a planet/moon orbiting a planet that was orbiting a blue star would be yellow.

Would this be the case? I thought the reason the sky was blue here was that the shorter wavelengths of light (i.e. blue) are scattered and diffused by the particles in the atmosphere and create a sort of blue "glow". A blue star would presumably give off much more blue light than our star, so the sky would still be blue, but the star on that planet would possibly appear much bluer than our star appears on Earth. Although, I guess the thickness of the atmosphere would affect the color output, since the generally accepted reason that sunsets tend towards yellows and reds is that the sunlight has to travel through much more atmosphere.

Basically, I am trying to find out what a blue star (or other colors of stars) and the sky would look like to people on a planet orbiting that star. What would affect the colors? Would a planet orbiting a blue star possibly have a thicker atmosphere to protect the life from the extra radiation that would be given off? If so, would the planet have to be larger or have a stronger gravitational pull in order to have a thicker atmosphere?

By the way, the reason I am asking is that I am creating a world for an assignment in a class. While the world does not have to be scientifically sound (it could be completely loopy and non-rational), I tend to prefer my creations to have some basis in reality and to be at least scientifically plausible, if not completely realistic! I was hoping to create a world that is slightly askew from Earth, with ad different color sky and such.

My apologies for the rambling! And thank you in advance for any help y'all can offer! :)

2003-Nov-07, 10:32 PM
Light with shorter wavelengths are scattered the most, thats why we see the sjy as being blue. In fact violet is scattered the most, but human eyes cannot detect this color as easily as blue, so thats why the sky is blue instead of violet. The atmosphere and light from the sun look red at sunset because the light has to travel through more atmosphere so the blue/violet, is scattered into longer wavelengths of light.

So I suppose if your atmosphere was thicker, or was very dusty, the sky would be of a color with a longer wavelength.

2003-Nov-07, 10:39 PM
Also, the type of gas the atmosphere is comprised of obviously affects how the light is refracted. Nitrogen is what gives Earth's atmosphere its blue colour (the same reason that electric sparks in our air appear blue). Sounds like an interesting assignment! Good luck with it all.


2003-Nov-07, 11:01 PM
My daughter did just fine on her assignment. I credit Planetwatcher for allowinf her to borrow his ideas. Her planet was actually a moon orbiting a gas giant, which in turn orbited a blue dwarf star. She made a B. For some reason, she insisted on doing her own work. She told me if I wanted to design a planet, I had to do my own! Kids. She had to create a conflict and solve it. Again, thanks to Plnaetwatcher, she decided a couple of nations were having a space race to an inner habitable planet. Unlike Earthlings, the beings on this planet decided to work together and share the rewards. I think she lost points on the landforms. Phryn, good luck on your assignment.

2003-Nov-12, 05:28 PM
Thank you!

I have found some other interesting sources that may help others trying to do the same sort of thing:

World Builder's Web Page - for a course on building worlds:

A book called "World-Building: A writer's guide to constructing star systems and life-supporting planets" by Stephen L. Gillett

2003-Nov-12, 08:56 PM
The main factor of sky color is the elements it is made of.
I don't know which ones would have made a yellow sky, I just thought it would look like a neat change.
But my other thought is that a blue star is much brighter then a yellow, and therefore make the sky brighter, hence a brighter color.

As for the complaments and other mentions, Thank you guys. You just made my day. Now I got to go to work. Bye.