---
source: https://iinventedlight.com/library/notes/sunspots-solar-cycle.md
title: "Sunspots and the 11-year solar cycle"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "US government work, public domain; restated in our own words"
attribution: "Summary by iinventedlight (AI-assisted). Sources: NOAA SWPC, Sunspots/Solar Cycle, US government work, public domain; NASA, Sun: Facts, US government work, public domain."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-04
status: published
checked_on: 2026-11-04
as_of: 2026-11-04
confidence: medium
untested: "No observation or experiment was done; only the fetched government pages were read."
category: coverage-gaps
topic_area: "science-explain: space weather"
tags: science, sun, sunspots, space-weather
sources:
  - id: S1
    title: "Sunspots/Solar Cycle"
    publisher: NOAA SWPC
    url: https://www.swpc.noaa.gov/phenomena/sunspotssolar-cycle
    accessed: 2026-11-04
    license: "US government work, public domain"
  - id: S2
    title: "Sun: Facts"
    publisher: NASA
    url: https://science.nasa.gov/sun/facts/
    accessed: 2026-11-04
    license: "US government work, public domain"
---
# Sunspots and the 11-year solar cycle

## Short answer
Sunspots are dark patches on the Sun's visible surface where intense magnetic fields push up from inside. They look dark because they are slightly cooler than their surroundings. Their number rises and falls with the roughly 11-year solar cycle. [S1][S2]

## Key points
- The Sun's visible surface is the photosphere; it is plasma, not solid. [S2]
- About every 11 years the Sun's magnetic poles flip, marking a cycle of high and low activity. [S2]
- Around solar maximum, more sunspots mean more flares and eruptions that can affect Earth. NOAA tracks and predicts sunspot numbers. [S1]

## Claims
- id: C1
  claim: Sunspots result from intense magnetic flux pushing up from the solar interior.
  source: S1
  evidence: "as a result of intense magnetic flux pushing up from further within the solar interior"
- id: C2
  claim: Sunspots are slightly cooler than the surrounding photosphere.
  source: S2
  evidence: "slightly cooler than the surrounding photosphere"
- id: C3
  claim: About every 11 years the Sun's poles change magnetic polarity.
  source: S2
  evidence: "Approximately every 11 years, the Sun’s geographic poles change their magnetic polarity"
- id: C4
  claim: The Sun has no solid surface because it is plasma.
  source: S2
  evidence: "The Sun doesn’t actually have a solid surface because it’s a ball of plasma."

## Sources
- [S1] Sunspots/Solar Cycle. NOAA SWPC. https://www.swpc.noaa.gov/phenomena/sunspotssolar-cycle . License: US government work, public domain. Accessed 2026-11-04.
- [S2] Sun: Facts. NASA. https://science.nasa.gov/sun/facts/ . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).