Starship Asterisk*

Thanks for your contributions, Art - particularly contributions like these! :wink:

It's good to have you back again.

Ann

[quote="Chris Peterson"][quote="FLPhotoCatcher"]

Does a single atom moving through a perfect vacuum radiate more photons the faster it is traveling?[/quote]
No[/quote]
A [b][u]relativistic[/u][/b] atom moving through a perfect vacuum radiates [b][u]fewer[/u][/b] photons the faster it is traveling thanks to time dilation.

[float=right][img3="[b]Comparison of [color=#FF0000]Gaussian (red)[/color] & [color=#0000FF]Lorentzian (blue)[/color] standardized line shapes.[/b]"]https://upload.wikimedia.org/wikipedia/commons/d/d1/Gauss_and_Lorentz_lineshapes.png[/img3][/float][quote="Chris Peterson"][quote="FLPhotoCatcher"]

Does an atom in motion need to hit another atom to radiate photons?[/quote]
No. Normally an atom is hit by a photon- a quantum of energy.[/quote]
An atom in motion needs to hit another atom in order to radiate photons of a significantly different frequency:

The broad spectral wings of a [b][color=#0000FF]Lorentzian line shape[/color][/b]
are primarily due to collisions. :arrow:

The density (and/or temperature) of astronomical gases can often be determined simply by the shape of the spectral lines.

[quote="FLPhotoCatcher"]I was wondering about how atoms in space radiate photons. Do atoms radiate more photons the faster they are traveling?[/quote]
Only to the extent that they are emitting photons because of some interaction with other matter. That happens, but isn't generally what we're seeing in astronomical images, where photons are emitted by simple ionization processes. An atom absorbs a photon (which either results in ionization, or an electron in an temporarily high energy level), and then drops out of that state, producing a new photon with a characteristic wavelength. That process is the same whether the atom is stationary or moving.

[quote]Does a single atom moving through a perfect vacuum radiate more photons the faster it is traveling?[/quote]
No

[quote]Does an atom in motion need to hit another atom to radiate photons?[/quote]
No. Normally an atom is hit by a photon- a quantum of energy.

A rather intriguing picture. I like the stars twinkling through the pinkish swirls.

Great photo!

This comment section needs more comments, so...

I was wondering about how atoms in space radiate photons. Do atoms radiate more photons the faster they are traveling? Does a single atom moving through a perfect vacuum radiate more photons the faster it is traveling? If so, how does the idea of "motion is relative" NOT apply? Does an atom in motion need to hit another atom to radiate photons?

Thank you APOD and Adam Block for gifting us this combination of art and science.

The wispy figure looks like the Creature from the Pink Lagoon but I'd hate to see this [url=http://www.imdb.com/title/tt0436200/]linked[/url] to a bad movie. :wink:

I think the stars are hotter in Adam's version though "[url=http://www.star.ucl.ac.uk/~pac/obafgkmrns.html]Oh be a fine guy - kiss me now[/url]" might be relevant in both. :lol2:

That is just INCREDIBLE.... :clap: :clap: :clap:

:---[===] *

I'm very glad to see Adam Block, one of the most tireless cartographers of the heavens, get an APOD again. His portrait of the Lagoon Nebula is beautifully detailed as well chromatically "correct", and I'm very grateful for the latter.

I'm so grateful to Adam for all the stunning RGB images he has made, not least his fantastic collection of galaxy pictures.

Ann

[url=http://apod.nasa.gov/apod/ap150729.html][img]http://apod.nasa.gov/apod/calendar/S_150729.jpg[/img] [size=150]The Deep Lagoon[/size][/url]

[b] Explanation: [/b] Ridges of glowing interstellar gas and dark dust clouds inhabit the [url=http://hubblesite.org/newscenter/archive/releases/1996/38/image/b/]turbulent, cosmic depths[/url] of the Lagoon Nebula. Also known as M8, The bright star forming region is about 5,000 light-years distant. But it still makes for a popular stop on [url=http://apod.nasa.gov/apod/ap141125.html]telescopic tours[/url] of the constellation Sagittarius, toward the center of our Milky Way Galaxy. Dominated by the telltale red emission of ionized hydrogen atoms recombining with stripped electrons, [url=https://www.adamblockphotos.com/m8-the-lagoon-nebula.html]this stunning, deep view[/url] of the Lagoon's central reaches is about 40 light-years across. Near the center of the frame, the bright hourglass shape is gas ionized and sculpted by energetic radiation and extreme stellar winds from a [url=http://apod.nasa.gov/apod/ap140820.html]massive young star[/url].

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