George

You are, of course, correct, but I thought that went without saying…so I didn’t say it. If we couldn’t see it, it wouldn’t be part of the visible spectrum. (I’m really tempted to put a “duh!” here, but I don’t want to be insulting…)

“Myself, I often wish the visible range was more than just a tiny little snippet of the whole spectrum (that just happens to coincide with the range in which both water and our atmosphere are transparent).”

If air and water weren’t transparent at these wavelengths, then I doubt that we would have evolved to see them.

- Jack

As the gas in the Sun roils and swirls, the field lines get tangled together. If they connect, bang!

makes it sound the “Ghostbuster crossing their streams”, but what needs to happen is that two sets of field lines with an angle of more than 90° between them (0° would be aligned the same way, 180° is aligned in opposite directions, e.g., one going East and one going West). Such field lines repel each other, so it takes some squeezing for this to happen. And that is where the violent convection in the surface layers (“the gas in the Sun roils and swirls”) comes into play: Every now and then convection will bring field lines so close together that the very small resistance of the plasma will make a kind of “short-circuit” and perform a X-type reconnection. Think of the field lines being parallel at first: || and then being forced together in the middle )(, into an X, reconnect into an upper and a lower part (turn the sequence X )( || onto its side) rushing away from the reconnection point due to magnetic tension. The plasma will largely follow the magnetic field, which means the reconnection event can be a rather efficient plasma slingshot.
Cheers, Regner

Guess I should get out my magnetic umbrella.

Gary 7

Is it a good or bad thing that “Star Trek” is cited as a valid precident for Astronomical Nomenclature?

Not sure of that exactly either!

I’m being practical there in how its likely to be conventionally pronounced by others rather than meaning to imply any approval or disapproval of the sources validity.

As I noted before, I’d say (hah!) the main thing is that people understand which star it is we’re talking about. I’ve discussed this before in past threads mainly on what to call significant exoplanets and I think the catalogue names do impede communication with the public and would be better replaced with real names – not numerical codes.

I’d find that discussion for y’all now but for the fact that I need to get some sleep soon. After 2.30 am in my timezone now.

http://en.wikipedia.org/wiki/Wilhelm_Gliese

& his catalogue :

http://en.wikipedia.org/wiki/Gliese_Catalogue_of_Nearby_Stars

Interestingly, the fact that seems that Gliese 581 is often shortened to GJ 581 would indicate it was from the second later volume of Gliese’s listing co-written by Richard van der Riet Woolley and associates or later still Hartmut Jahreiss.

@#9. Messier Tidy Upper: Or anyone else with that knowledge, for that matter: How would one pronounce ‘Gliese 581′, ‘properly’? ‘Gliese Five Eight One’, ‘Gliese Five-Eightyone’ or something else I can’t come up with? Sorry for the rather random off topic question, but that kinda bugged me for a while now.

No worries – good question.

Honestly, I’m not sure myself & wish I could answer it better for you.

The name comes from it being (I think) the five hundred and eighty-first star in the catalogue of nearby stars produced by Wilhelm Gliese back in 1957 and additional volume in 1969. (source : wikipedia links appearing soon – hopefully.) That would suggest five hundred and eighty one is correct.

That noted, there’s also the precedent set in Star Trek with Wolf 359 that also seems to be commonly heard with spelling out the numerals individual thus three-five-nine / five-eight-one.

I’m really not sure. As long as folks understand which star we’re talking about it probably doesn’t matter overly but the use of numbers in place of proper star names is a pet gripe of mine. At least its only a managable three numbers not a whole string of them like in many other cases.

Behold the Purple-Leaf Plum Tree:
http://treesandshrubs.about.com/od/commontrees/p/PurpleLeafPlum.htm

Now imagine all of your power going off for days, weeks, months….. years? You get the picture.

http://www.youtube.com/watch?v=fOWWIDT910I

Sorry for the rather random off topic question, but that kinda bugged me for a while now

http://www.facebook.com/photo.php?pid=6643552&l=36cec28661&id=598831773
http://www.facebook.com/photo.php?pid=6643554&l=dd100a22f9&id=598831773

Presumably it’s no coincidence that it’s also a local maximum of the sun’s average output and the color of many nutritious-yet-immobile life forms.

Sorry, but if I understand you correctly, you are wrong.
Plants are green because they do NOT use the green part of the spectrum. They absorb and consume all the other light-forms and reflect the green part, hence they look green.

Well actually, aurora australis is occasionally seen as far north as Brisbane (latitude 27 deg 28 min S) and moderately frequently in Melbourne and surrounds (latitude 37 deg 50 min S).

Mind you, the aurora generally only appears in those locations as a suffuse pinkish and sometimes greenish glow, but I have personally witnessed a ‘pink glow’ aurora in Melbourne that was bright enough to have a few thousand people calling in to report a large ‘fire’.

Otherwise, you are quite correct.

Magnetic Field LINES does not exist.
There is no such thing as magnetic reconnection.

Cheers