| Solar cycle 15 | |
|---|---|
 Sunspots recorded during solar cycle 15 (23 January 1923). | |
| Sunspot data | |
| Start date | July 1913 |
| End date | August 1923 |
| Duration (years) | 10.1 |
| Max count | 175.7 |
| Max count month | August 1917 |
| Min count | 2.5 |
| Spotless days | 534 |
| Cycle chronology | |
| Previous cycle | Solar cycle 14 (1902–1913) |
| Next cycle | Solar cycle 16 (1923–1933) |
Solar cycle 15 was the fifteenth solar cycle since 1755, when extensive recording of solar sunspot activity began.[1][2] The solar cycle lasted 10.1 years, beginning in July 1913 and ending in August 1923. The maximum smoothed sunspot number observed during the solar cycle was 175.7 (August 1917), and the starting minimum was 2.5.[3] During the minimum transit from solar cycle 15 to 16, there were a total of 534 days with no sunspots.[4][5][6]
- ^ Kane, R.P. (2002), "Some Implications Using the Group Sunspot Number Reconstruction", Solar Physics, 205 (2): 383–401, Bibcode:2002SoPh..205..383K, doi:10.1023/A:1014296529097, S2CID 118144552
- ^ "The Sun: Did You Say the Sun Has Spots?". Space Today Online. Retrieved 12 August 2010.
- ^ SIDC Monthly Smoothed Sunspot Number. "[1]"
- ^ Spotless Days. "[2]"
- ^ Dr. Tony Phillips (11 July 2008). "What's Wrong with the Sun? (Nothing)". NASA. Archived from the original on 14 July 2008.
- ^ Solaemon's Spotless Days Page. "[3]"