Planck Mission Releases Images of Galactic Dust 40
davecl writes "The Planck satellite has released its first new science images, showing the large scale filamentary structure of cold dust in our own galaxy. This release coincides with the completion of its first survey of the entire sky a couple of weeks ago. There's lots more work to be done, and more observations to be made, before results are ready on the Big Bang, but these images demonstrate Planck's performance and capability. More information is available on the Planck mission blog (which I maintain)."
Re:Size? (Score:5, Informative)
When talking about things at the galaxy scale, what is considered dust? Is this actual real "dust" of the size that collects on my shelves, grains of sand sized bits, gravel, or something larger?
The phrase to google for is "cosmic dust"
You'll be displeased with the answer, it seems to be a very wide range of stuff from two molecules having a public display of affection all the way up to the low end of vaguely sand-like.
I don't really know what collects on your shelves, but "cosmic dust" is probably vaguely similar.
This sand and gravel stuff you talk about, is by definition a "meteor".
http://en.wikipedia.org/wiki/Cosmic_dust [wikipedia.org]
http://en.wikipedia.org/wiki/Meteor [wikipedia.org]
Re:Size? (Score:4, Informative)
Re:High-Res? (Score:4, Informative)
They consider 1000x892 pixels high resolution? Last I checked, that was high res circa 1995..
For marketing / PR / Journalist folks that is high-enough res... it'll look OK on a HDTV, a web page, or in a 100 dpi B/W newspaper. They call it a "press" release for a reason, not a science release or a data release.
If you want 2000x1500 or whatever, I think you're asking for the science data, which is not released yet. Usually the way it works with space probes is the folks whom ran it keep the data to themselves for "awhile" before its released to the public. Usually "about a year". No idea how it works with Planck, couldn't even google it.
Since the public doesn't really care (just being honest here) I think the main purpose of early press releases is to intimidate the researchers whom aren't in the inner circle whom have actual data.
I did find a nice description of the HFI "imager" device... Its resolution is about 5 arc minutes depending on frequency, etc.
Your eyes resolution is about 1 arc minute. So, the output of the HFI would be a slightly blurry version of what your eyes see, sort of. Just drink a few beers and drop some acid and look at the stars and you'll be pretty much on your way.
I did not bother researching the other instruments on Planck. Someone with more motivation can do that and gain the karma.
http://xxx.lanl.gov/ftp/astro-ph/papers/0308/0308075.pdf [lanl.gov]
http://en.wikipedia.org/wiki/Visual_acuity [wikipedia.org]
Nice try (Score:4, Informative)
Re:Size? (Score:5, Informative)
APOD has a good description and picture (well, computer-generated visualization) of dust:
By studying how dust absorbs, emits, and reflects light, astronomers do know that interstellar dust is much different than the cell and lint based dust found around a typical house. Interstellar dust grains are composed mostly of carbon, silicon, and oxygen and are usually less than about 1/1000 of a millimeter across. Recent work indicates that most dust grains are not spherical. The above picture shows the result of a fractal adhesion model for dust grains involving random conglomerates of spherical compounds of different properties, here artificially highlighted by different colors.
(from http://apod.nasa.gov/apod/ap961119.html [nasa.gov])
Re:Size? (Score:4, Informative)
So, umm... with all that dust out there, is it possible that light could be attenuating between here and the perceived "edge" of the universe? Couldn't the presence of large amounts of dust mean that our universe is larger than current estimates?
Think of it like your headlights on a dark night... the further away you get the more light disperses. Since there's less stuff in space to disperse light, we can see for X billion light years, but the presence of dust could be masking a large portion of visible space in this manner. I would assume this would have to happen, otherwise space would be white with light instead of black, right?
It's well known that there's a lot of dust, that doesn't hurt our understanding of the size of the observable universe. It might increase our error bars a little in the first few steps of the distance ladder (http://en.wikipedia.org/wiki/Distance_ladder), but probably not significantly. Dust isn't an effective absorber of every wavelength of light, so we can see through it if we want.
If you really want to get a good handle on this rather complex and fascinating topic, read the above article and the less awesome but still useful article on the size of the observable universe (http://en.wikipedia.org/wiki/Size_of_the_universe).
Re:Size? (Score:2, Informative)
"Couldn't the presence of large amounts of dust mean that our universe is larger than current estimates?"
No, because current measurement of the size of the observable universe is not based on brightness but is based on redshift.
Re:Size? (Score:2, Informative)
It's also pretty thinned out, often where it takes light years' worth of a "cloud" of it to finally provide enough coverage to 100% block out the stars behind it.