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Last Post 10/20/2008 9:57 AM by Lyndsay Fletcher

sun spots

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Jim Stryder

Basic Member

Posts:105

10/20/2008 8:13 AM
Reuben (Fx) 4th grade How come sunspots come in different sizes, and why are there none right now on the sun?

KD Leka

Basic Member

Posts:115

10/20/2008 9:51 AM
Hi -- good questions! Regarding the different sizes, I have two answers. First, there are some limits on how small and how large sunspots can be which have to do with the balance of the pressure of the gas and plasma surrounding a sunspot, and the pressure of the magnetic fields inside a sunspot. If you think about a balloon, too little (air) pressure inside and it won't inflate properly, too much much air pressure inside and it pops. For sunspots there is a similar balance between the magnetic fields that are in the sunspots and their surroundings: wrong balance and then the spots either don't form or break themselves apart very fast. The second answer is simply, ``we don't know'' why some sunspots become really huge and some stay tiny. We have some ideas about why they never get so big as to take over the entire Sun which have to do with how fast the Sun is rotating and the details of the structure of the solar convection zone (inside the Sun, near where the magnetic fields are stored and re-generated). But we are actively researching why sunspots can be big, little, simple or very complicated. There are few if any sunspots on the sun right now because we are at the minimum part of the 11-year activity cycle. I'd suggest going and reading some of the posts on that topic for additional details. cheers, -KD

Lyndsay Fletcher

New Member

Posts:32

10/20/2008 9:57 AM
Hi Reuben Sunspots come in different sizes because their size depends on how strong the solar magnetic field is, and that varies from place to place on the Sun. It's a bit complicated but basically the stronger and more complicated the magnetic field, the bigger the spot. We get lots of big spots when the Sun's magnetic field is strong, and only a few smaller spots when it is weak. We know that the strength of the Sun's magnetic field changes over time (like the Earth's does, in fact, though that takes a lot longer to change) but we are still not sure exactly why. Right now there are indeed no spots at all on the Sun. The number of spots on the sun increases and then decreases again every 11 years - this has been known for a couple hundred years now. Right now we are in a time called 'solar minimum' when there are no spots. But the slightly strange thing is that this solar minimum has been going on for about a year longer than it did the last couple times, and we are starting to wonder when all the spots are going to come back! thanks for your question Lyndsay