Solar Cycles And Parisian Scooters -- June 19, 2019

Enquiring minds want to know: why is this "solar cycle 24?" From wiki:

Solar Cycle 24 is the 24th solar cycle since 1755, when extensive recording of solar sunspot activity began.

It is the current solar cycle, and began in December 2008 with a smoothed minimum of 2.2 (SIDC formula). Activity was minimal until early 2010.

It reached its maximum in April 2014 with a 23 months smoothed sunspot number of only 81.8, comparable to those of cycles 12 through 15. Reversed polarity polar active sunspot regions in December 2016, April 2018, and November 2018 indicate that a transitional phase to solar cycle 25 is in process.

The most recent update, March, 2019:

NOAA reported that the number of sunspots was the lowest since 2009, and that recent activity matched that of the low activity in 2007 and 2008.

Should this prove to be the solar minimum, Solar Cycle 24 would uniquely become a short (10 year) and weak cycle. Sunspots were observed on only 5 days that month.

Uniquely?

1755: famous 18th century astronomers ..  we can start with these --

• William Herschel. 15 November 1738. German, British.
• Pierre-Simon Laplace. 23 March 1749.
• Benjamin Banneker. 09 November 1731.
• Edmond Halley. 08 November 1656.
• Mikhail Lomonosov. 19 November 1711.
• Anders Celsius. 27 November 1701.
• Caroline Herschel. 16 March 1750.
• Charles Messier. 26 June 1730.

Solar cycle 1: 1755 - 1766. From wiki --

Cycle #1 was discovered by Johann Rudolph Wolf who, inspired by the discovery of the solar cycle by Heinrich Schwabe in 1843, collected all available sunspot observations going back to the first telescopic observations by Galileo. He was able to improve Schwabe's estimate of the mean length of the cycle from about a decade to 11.11 years.

However, he could not find enough observations before 1755 to reliably identify cycles, hence the 1755–1766 cycle is conventionally numbered as cycle #1. 

Wolf published his results in 1852.

Samuel Heinrich Schwabe (25 October 1789 – 11 April 1875) was a German astronomer remembered for his work on sunspots.

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Exploring Paris

The granddaughters found the perfect way to explore Paris.

They will never want to return home! Sophia who has just learned how much fun her Razor scooter is will be very envious when she sees these photos.