Sunspots Return 276
We're emerging from the longest, deepest sunspot drought since 1913 (we discussed its depths here) with the appearance of a robust group of sunspots over the weekend. Recently we discussed a possible explanation for the prolonged minimum. The Fox News article quotes observer Michael Buxton of Ocean Beach, Calif.: "This is the best sunspot I've seen in two years." jamie found a NASA site where you can generate a movie of the recent sunspot's movement — try selecting the first image type and bumping the resolution to 1024. The magnetic field lines are clearly visible.
Re:"The magnetic field lines are clearly visible. (Score:5, Informative)
No, the magnetic field is real but invisible. Magnetic field lines, on the other hand, are simply a mechanism for representing (e.g., on paper) magnetic field orientation and strength. The lines themselves are not real. (Compare with, for example, a topographical map. The height of the earth's surface is real, but the lines on a topographical map are a representation of height; they're not real.)
It's actually not much of a sunspot group. (Score:5, Informative)
Go check it out at http://www.solarcycle24.com/ [solarcycle24.com]
This guy's everything about the sun that one can track. In particular, he has an image of the sun on the upper left hand corner that shows how pathetic this sunspot group.
I wouldn't say the sunspot drought is over, until there is sustained progress.
Re:Well, now we'll know. (Score:3, Informative)
Re:Well, now we'll know. (Score:2, Informative)
Could you back this up with some data. If anything, the inverse is true. The last 50 years have seen a large increase in the number of sunspots per solar cycle.
Re:"The magnetic field lines are clearly visible. (Score:1, Informative)
"The iron filings in the photo appear to be aligning themselves with discrete field lines, but in actuality, they are creating the field lines by concentrating the magnetic field along a random topographic path, and not along any line that actually exists in the field. In other words, the lines formed by the iron filings would not exist without the iron filings, and so the magnetic field lines you see are a not a demonstration of a lines in the magnetic field. Magnetic fields are continuous, and do not have discrete lines."
Wikipedia [wikipedia.org]
Re:"The magnetic field lines are clearly visible. (Score:5, Informative)
Magnetic field lines are not really like the lines on a topographic map. The lines of a magnetic field represent paths from high potential to low potential, rather than delineations of equal-potential regions.
It's more like a river. The river flows perpendicular to the lines on the topographic map, from high to low, and its "line" is quite real, while the lines on the topographic map are not. Thus it is an unfair comparison to say magnetic field lines are "imaginary" in the same sense that contour lines on a map are. You cannot physically demonstrate the contour lines on a map, whereas you can demonstrate (with water or iron filings, as the case may be) a path from high potential to low potential.
IOW, inasmuch as there is a very real path that a drop of water will take when placed at any specific point on a 3-D surface, there is also a very real path that an electron will follow from a specific starting point in a 3-D electromagnetic field.
The lines themselves are imaginary, but they are real paths. Of course, there are infinitely many of the paths, densely packed, and so we pick only a few representative paths and call them the "magnetic field lines".
Re:"The magnetic field lines are clearly visible. (Score:3, Informative)
That they are discrete, perhaps, is a misconception. You won't hear me claiming they're discrete.
A continuous field contains infinitely many paths from high to low potential, all of which are "lines". A representative few are used to approximate the field when we're drawing it, which leads to the misunderstanding about them being discrete.
Re:Well, now we'll know. (Score:5, Informative)
I saw the tag but haven't seen this explicitly mentioned yet: one theory is that lack of sunspots causes Earth to warm up. (There is a very strong negative correlation between sunspot activity and temperature on Earth.
Nope. People have been looking for correlations between sunspots and weather for years, but never found much. If there's a correlation, it's weak. http://www.crh.noaa.gov/fsd/astro/sunspots.php [noaa.gov]
To the extent that there's any correlation, however, it tends to the the opposite of what you said-- positive correlation between sunspots and temperature, not negative. The "Maunder Minimum" period of very few or no sunspots occurred about the same time as the "Little Ice Age" of cold temperatures. (But note that a single period of low temperatures ocurring during a period of low sunspots, however extended, does not mean statistically significance).
If that correlation were indeed true, then the recent solar minimum would have been correlated with low temperatures, and hence would have been masking some of the effect of global warming-- in other words, that greenhouse-effect warming is actually occurring to a greater extent than the data shows.
Re:Man saved Earth? (Score:2, Informative)
IIRC, the last time sunspots were at a minimum like this, earth was in the little ice age
No; during the little ice age there was ~50 years of almost no sunspots; we've only had ~2. There was a solar minimum earlier this century deeper than this one (unless this one goes on for a while yet).
Re:Is it just me ? (Score:5, Informative)
Because local climate suddenly equates to global mean temperature? Huh... go figure...
Re:"The magnetic field lines are clearly visible. (Score:2, Informative)
That is one way to think about it but that isn't entirely correct. A line is a discrete mathematical construct. A field is a continuous function but a "line" is not. Think about it this way: let's say you have a piece of paper and some "string". You place several piece of string on the paper. There is "space" in between the pieces of string. You then proceed to add pieces of string in between the others. You can continue to do this ad infinitum (assuming smaller and smaller pieces of string) but they will never match the piece of paper, i.e. the continuous field. They can approximate it but it will never be the same.
In this way, the magnetic field "line" is a mathematical construct used to determine topology. Electric field lines and gravity field lines are much the same thing. There is nothing wrong with saying "magnetic field line" save that iron filings or plasma or whatever is not on a line but in a field. They can be used to visualize the field, so to speak.
Re:Well, now we'll know. (Score:4, Informative)
I'll see your YouTube video, and raise you one:
video [youtube.com]
video [youtube.com]
And a whole bunch of articles:
article [typepad.com]
article [wordpress.com]
article [bbc.co.uk]
article [examiner.com]
article [mlive.com]
article [wordpress.com]
Re:wow. (Score:0, Informative)
Re:"The magnetic field lines are clearly visible. (Score:1, Informative)
> there is also a very real path that an electron will follow from a specific starting point in a 3-D electromagnetic field.
Yes, there is such a path. And that path is most certainly *not* a magnetic field line. An electron in a magnetic field is acted on by a force perpendicular to the field lines. Your error is just as bad (in much the same way) as the error you seek to correct.
Electrons may follow paths that spiral *around* and along magnetic field lines. It's these paths that give rise to the loops we see in the sun's corona when we look in the frequency band.
Re:"The magnetic field lines are clearly visible. (Score:2, Informative)
No. Think of each integral as "stretching" to the next dimension. The path become a surface, etc.
I think there is a bit of difference in thinking here. Most people are thinking of a line as a discrete thing that iron filings or plasma or whatever exist on, making the "lines" real. That was what I was trying to show with my example. You have the correct thought that the "line" is just a mathematical construct - your integration shows this.