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Questions tagged [sunspots]

Questions regarding the darker areas on the solar disk formed by emerging magnetic fields.

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1 answer
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What is a place to find raw numbers of sunspots from the past, as counted daily by sun observer?

What is a place to find raw numbers of sunspots from the past, as counted by sun observers ? I have already visited 100+ of websites (NOAA, NASA, ESA, Japanese Institute ..) and what is offered is ...
3 votes
1 answer
61 views

Most established length of Gleissberg Cycle

What is the most commonly used length for the Gleissberg Cycle of sunspots? I have reviewed academic literature on the subject and the lengths used are all over the place. Specifically, anywhere in ...
6 votes
3 answers
1k views

What is the meaning or information given by the solar image at 4500Å?

On the latest solar images from NASA, there is one picture lablled "continuum 4500 Å". There are bands diagonally in the picture as well. What is the ...
2 votes
0 answers
134 views

How to build functional sunspot model on the ground with high-power plasma burners in the strong magnetic field as conference paper?

I need to build functional sunspot model on the ground with high-power plasma burners in the strong magnetic field as conference paper. What I get is light-weight plasma, as exactly plasma is. But I ...
1 vote
0 answers
56 views

How does the entropy diffusivity changes with radius in the Sun?

Could you please explain - How does the entropy diffusivity changes with radius in the Sun? As far I know, In the convection zone, the entropy diffusivity increases as the temperature and density ...
3 votes
0 answers
165 views

How a sunspot number is calculated by an individual observer?

How a sunspot number is calculated by an individual observer? I would like to learn how to calculate the daily number of sunspots and where to get daily input images of the Sun. I have read tens of ...
2 votes
0 answers
135 views

Help finding a database or analysis of plage regions on the Sun

Plages are phenomena of stellar activity. A plage is a bright region in the chromosphere of the Sun, typically found in and around active regions. The term itself is poetically taken from the French ...
7 votes
1 answer
702 views

What do "P" and "F" mean in the compass legend of Carrington's sunspot drawing?

In Richard Carrington's drawing of sunspots, he has a compass labeled "N", "P", "S", and "F". If "N" is North and "S" is South, what do &...
6 votes
3 answers
447 views

Can we see evidence of sunspots on other stars? (starspots)

Searching for exoplanets by measuring the change of a stars brightness when an exoplanet transits the star's disk also has the potential to detect exo-sunspots (starspots). Have they ever been ...
2 votes
1 answer
686 views

What are Ellerman bombs and how can we identify them?

Have you ever heard about Ellerman bombs? Spaceweather.com talks about them on their news page. You could see some of them around sunspot AR2835: Ellerman bombs are magnetic explosions about one-...
4 votes
0 answers
90 views

Sun (star) spots (size)

My question is about sunspots size. Does these spots have a 'typical' size for all kinds of stars (dwarves or super giants), or are they dependent on a star size? In another words, is the statement ...
8 votes
1 answer
501 views

Wilson effect: How "deep" are sunspots?

I recently learned about the Wilson effect of the Sun's atmosphere. The 2009 Saas Fee Advanced Course 39 states: Near the solar limb, the umbra [the circular dark region of a sunspot] and the centre-...
12 votes
1 answer
4k views

Why do sunspot rise in number "precisely" every eleven years?

Every eleven years (more or less precisely) sunspots are seen to rise in numbers. The magnetic field of the sun changes polarity over eleven years and this is the reason the number of spots can vary. ...
0 votes
1 answer
143 views

Why is the 11 yr sunspot cycle less predictable recently?

I quoted from a similar question on solar minima and maxima. "...I guess the jury is still out, but this is quite "fringe" material. The solar cycle is certainly thought to be a product ...
14 votes
3 answers
3k views

How are the solar flares from May 23, 2021 extraordinary?

The Space Weather News for May 23, 2021 reads (with some highlighting by me) Yesterday, the sun produced a sequence of solar flares unlike anything we've seen in years movie. Earth-orbiting ...
27 votes
2 answers
24k views

Why do sunspots appear dark?

Sunspots, such as this one, appear dark: Why?
1 vote
0 answers
249 views

Are sunspots named or individually tracked?

This is a follow-up question to How are the solar flares from May 23, 2021 extraordinary? which is about news of spaceweather.org. In the present question, I am curious solely about sun-spots and why ...
26 votes
3 answers
4k views

Why can't stars be multicolored like gas giants?

Gas giants like Jupiter and Saturn have bands of different colors in their atmosphere. These are due to the rotation of the planets. Stars rotate too, so why do most stars have patches/blotches of ...
3 votes
0 answers
142 views

Density of a sunspot compared to the surrounding photosphere?

Is the density of a sunspot different by more than a factor of ten compared to the area surrounding the sunspot?
4 votes
1 answer
93 views

Is there a database of past sunspots?

I would like to plot a butterfly diagram. I've been looking through the SOHO archive for a table that would indicate the date and position of each sunspot, but to no avail. The closest I got was to ...
1 vote
1 answer
107 views

Could Tabby's star be beamed by a neutron star's jet causing irregular star spots?

There have been some other questions here about what might cause the light curve dips of star KIC 8462852 as observed by Kepler Space Telescope. Here's one I haven't heard before: Could it be that a ...
4 votes
1 answer
196 views

Is the longitude assigned to sunspots spherical or projected?

Sunspot maps are created from a projection of the sun, so the coordinates of sunspots (or active regions in general) are assigned according to it. Do these coordinates correspond to actual spherical ...