Re: Ask an Astrophysicist - APOD's Dr. Jerry Bonnell
Posted: Wed Sep 08, 2010 5:05 am
I love the Buffer Brown and Tighe image!
Ann
Ann
APOD and General Astronomy Discussion Forum
https://asterisk.apod.com/
There is probably a difference betweenBobby Woods wrote:How many people do you think, like myself, read the APOD every single day?
The color of stars is mainly determined by their temperatures- they are approximately black body emitters, and the shape of a black body spectrum, combined with the responsivity of our eyes, means that there is no temperature that can produce green. There is a temperature where the peak wavelength is green (in fact, that's pretty close to our own Sun), but when mixed with all the other wavelengths, our eye sees something else. When you heat something up, from cold to hot it goes red-orange-yellow-white, with a hint of blue at the hottest end. Gas in the stellar envelope, or in the intervening space, can result in a shift of color, as can scattering and absorption by dust. But none of these mechanisms can really make a star look green.Curiosity wrote:Why are there no green stars?
They keep all the "green" stars hidden behind cloaks of dust and gas so that the only stars you see are mature stars that have been aged properly and are no longer considered "green".Curiosity wrote:Why are there no green stars?
Now I'm confused. Isn't the Moon made of well-aged green cheese? Are there different rules for stars and planetary satellites?bystander wrote:They keep all the "green" stars hidden behind cloaks of dust and gas so that the only stars you see are mature stars that have been aged properly and are no longer considered "green". :lol:
In that case, are all the really "old" stars grey and hiding in the dust and stuff alsobystander wrote:They keep all the "green" stars hidden behind cloaks of dust and gas so that the only stars you see are mature stars that have been aged properly and are no longer considered "green".Curiosity wrote:Why are there no green stars?
But when separated from all the other wavelengths, our eye sees green:Chris Peterson wrote:There is a temperature where the peak wavelength is green (in fact, that's pretty close to our own Sun),Curiosity wrote:Why are there no green stars?
but when mixed with all the other wavelengths, our eye sees something else.
Of course. For all the images we see on APOD, vastly more astronomical data is collected using spectroscopes, which do show precisely how much green is really there.neufer wrote:But when separated from all the other wavelengths, our eye sees green...
Chris Peterson wrote:Of course.neufer wrote:A horse is a horse...
Same rules apply, the green cheese the moon is made of is ripe (mature) green cheese not "green" green cheese, unless, of course, it's a blue moon, then it's made of ripe bleu cheese (not "green" bleu cheese).Chris Peterson wrote:Now I'm confused. Isn't the Moon made of well-aged green cheese? Are there different rules for stars and planetary satellites?bystander wrote:They keep all the "green" stars hidden behind cloaks of dust and gas so that the only stars you see are mature stars that have been aged properly and are no longer considered "green".![]()
Of course, and no one can talk to a horse, of course.neufer wrote:Chris Peterson wrote:Of course.neufer wrote:A horse is a horse...
Re: Why are there no green stars?Chris Peterson wrote:Now I'm confused. Isn't the Moon made of well-aged green cheese? Are there different rules for stars and planetary satellites?bystander wrote:They keep all the "green" stars hidden behind cloaks of dust and gas so that the only stars you see are mature stars that have been aged properly and are no longer considered "green".
Hey, thanks curiosity. I already knew Space was NUTS!!, but i had no idea that it was also Fruity!!curiosity wrote: Lemon slice nebula,IC3568
Good questions, both. I'll forward them to Dr. Bonnell, but I promise nothing.JeanTate wrote:Well, delaying my decision to register and participate in posting here means I missed the chance to ask questions in this thread!![]()
Just in case, though, here's one:
What do you think of the various citizen science projects that anyone (with a decent internet) connection can now join? Do you have any favorites?
OK, two questions.
How likely do you think it is that a new class of astronomical object will be discovered, from analyses of the data from Fermi? By analogy, RRATs were recently discovered by radio astronomers.