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What are Sunspots?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

Sunspots are areas on the sun's photosphere, or surface, which appear darker than the rest of the sun. The photosphere of the sun, or any gaseous celestial body, is the layer of gases which makes up the visible surface. On the sun, the photosphere is extremely deep, stretching for hundreds of miles. Beneath the photosphere lies the solar core, the powerhouse of the sun, which produces energy and heat. Primarily this is accomplished by converting hydrogen into helium in a form of nuclear reaction. Sunspots stand out strongly against the bright surface of the sun, and have been observed for thousands of years.

In the 1600s, sunspots were more closely documented and generally accepted. Numerous writings and drawings from previous periods show that observers saw areas of apparent darkness on the surface of the sun. Sunspots appear dark because they are cooler than the rest of the surface of the sun, but they are actually extremely bright. They are irregularly shaped, and tend to appear in clusters or groups, always within five to 35 degrees North and South of the sun's equator.

Sunspots may be seen with telescopes.
Sunspots may be seen with telescopes.

The cause of sun spots is a magnetic storm. The spots serve as a visual indicator of increased magnetic activity on that area of the sun, and they are commonly accompanied by coronal mass ejections, better known as solar flares. Heavy magnetic activity can impact life on Earth by disrupting communications and the weather, and may have led to climate anomalies in the past.

Areas on the sun's surface that appear darker than the rest of the sun are referred to as sunspots.
Areas on the sun's surface that appear darker than the rest of the sun are referred to as sunspots.

The sun is not the only celestial body to have characteristic spots marking magnetic activity. On other stars, the dark marks are known as “starspots.” In all cases, they appear to run in cycles. The sun has an 11 year solar cycle with periods of increased activity at the beginning and the end of the cycle. This cycle has been documented and studied since the 1800s, when astronomers began to probe more deeply into sunspots and the solar system in general.

Sunspots are usually accompanied by coronal mass ejections, or bursts of plasma.
Sunspots are usually accompanied by coronal mass ejections, or bursts of plasma.

Sometimes, sunspots are so large that they can actually be seen with the naked eye, although this would cause retinal damage. However, using filters and a weak telescope can reveal sunspots during periods of high activity. Astronomy observatories use heavy duty telescopes and roving space craft to aid them in their studies of sun spots. Published images of sun spots can be found, often with special filters applied to reveal solar flares and magnetic hot spots associated with the sunspots.

Frequently Asked Questions

What exactly are sunspots and why do they form?

Astronomy observatories use heavy duty telescopes to study sunspots.
Astronomy observatories use heavy duty telescopes to study sunspots.

Sunspots are temporary phenomena on the Sun's photosphere that appear as spots darker than the surrounding areas. They form due to interactions with the Sun's magnetic field, which reduce surface temperature in the affected areas. These magnetic activities inhibit convection, leading to cooler, darker regions. According to NASA, sunspots are cooler by about 1,500 degrees Celsius compared to surrounding areas.

How large can sunspots get?

Sunspots vary greatly in size, with some being just a few Earth diameters across, while others can grow to be much larger. The largest sunspots can span up to 50,000 kilometers in diameter, making them large enough to be seen from Earth without a telescope. However, it's important to never look directly at the sun without proper eye protection.

Are sunspots related to solar activity, and how do they affect Earth?

Yes, sunspots are indicators of solar activity and are often associated with solar phenomena like solar flares and coronal mass ejections. These events can release charged particles into space, which can interact with Earth's magnetosphere, leading to geomagnetic storms. Such storms can disrupt satellite communications and power grids on Earth, as reported by the Space Weather Prediction Center.

How often do sunspots occur?

Sunspots follow an approximately 11-year cycle known as the solar cycle. During the solar maximum, there are more sunspots, and during the solar minimum, there are fewer. The cycle is not perfectly regular, and the number of sunspots can vary from cycle to cycle. The current cycle, Solar Cycle 25, began in December 2019 and is expected to peak around 2025.

Can sunspots be used to predict solar flares?

While sunspots themselves are not a direct predictor of solar flares, regions with complex sunspot groups are more likely to produce significant solar flare activity. Scientists monitor these active regions using satellites like the Solar Dynamics Observatory to assess the potential for flares. The complexity and dynamic nature of sunspot groups can give clues about impending solar events.

Do sunspots have any effect on Earth's climate?

The influence of sunspots on Earth's climate is a subject of ongoing research. While sunspots themselves do not have a significant direct effect on Earth's climate, the solar activity associated with high sunspot counts can slightly increase the solar irradiance received by Earth. Over long periods, this may contribute to natural climate variability, but it is a minor factor compared to human-induced climate change.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AllThingsNature researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AllThingsNature researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

Discussion Comments

hamje32

@miriam98 - I’ve heard the same thing. Actually some scientists have noticed that current sunspot activity is greatly diminished compared to when global warming became a real concern in the late 1990s, and as a result the Earth is getting cooler.

I can understand the need to make that correlation. In my opinion any attempt to rule out the activity of the sun as having some influence (it is, after all, the sun which warms the Earth) would be foolish; however whether it is the primary cause, I don’t know. I’m sure the debates will continue.

miriam98

Years ago when I followed the global warming debate with some enthusiasm, I heard that some scientists were claiming sunspot activity was the prime cause of global warming and not carbon emissions.

They studied climate change over a hundred year period and noticed that global temperatures seemed to rise and fall in conjunction with sunspot cycles.

In short, the more sunspots, the more warming, and vice-versa. I don’t know if that’s really true but it’s interesting to get a different perspective on the topic.

anon155714

This was very helpful, thank you!

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    • Sunspots may be seen with telescopes.
      By: Monika Wisniewska
      Sunspots may be seen with telescopes.
    • Areas on the sun's surface that appear darker than the rest of the sun are referred to as sunspots.
      By: Michael Eaton
      Areas on the sun's surface that appear darker than the rest of the sun are referred to as sunspots.
    • Sunspots are usually accompanied by coronal mass ejections, or bursts of plasma.
      By: James Thew
      Sunspots are usually accompanied by coronal mass ejections, or bursts of plasma.
    • Astronomy observatories use heavy duty telescopes to study sunspots.
      By: skyphoto
      Astronomy observatories use heavy duty telescopes to study sunspots.