THE USM SOUTHWORTH PLANETARIUM

207-780-4249     www.usm.maine.edu/planet

70 Falmouth Street     Portland, Maine  04103

43.6667° N                   70.2667° W 
Altitude:   10 feet below sea level

Founded January 1970

Julian date:  2458639.5

                   "From the world of waking dreams."

THE DAILY ASTRONOMER

Wednesday, June 5, 2019

Quiescent Sun

Greetings!

We invite you to look below:

See them?  The Sun spots?

Well, perhaps not, as there are no Sun spots currently visible on the section of the solar surface.   Today is the 17th consecutive "spotless" day.    So far this year, we've experienced 91 spotless days.   No sunspots were visible on 221 days in 2018; 104 in 2017 and only 32 in 2016.      This apparent increase in spotless days has induced solar scientists to conclude that we are currently passing through a quiescent phase, known less pretentiously as a 'solar minimum.'

Every eleven years the Sun moves through a somewhat regular cycle of solar maximum to solar minimum.  The Sun shows an abundance of spots around maximum and a dearth around minimum.     See graphic below

For reasons that solar scientists haven't yet fathomed, the Sun has proceeded through these alterations of minima and maxima since record keeping began.  What is also uncertain is the effect this cycle has on our weather cycle.  It is possible that this impending minimum might reduce the solar constant (the measure of the solar energy reaching Earth) enough to cool our weather.  

We know that the solar constant at solar maximum is about 1,362 Watts per square meter.  At solar minimum, this constant measures about 1,361 Watts per square meter.   This variation is comparable to that we experience due to Earth's varying distance from the Sun.  The Solar constant varies by about 3 percent between our closest approach (perihelion, around Jan 3) and greatest distance (aphelion, around July 4th)  For this reason, many astronomers remain doubtful about the solar cycle's impact on our weather. 

On the other hand, between 1645 - 1715, the Sun experienced a protracted minimum,  called the "Maunder Minimum."   During those seventy years, the Sun exhibited a few dozen sunspots in a span of time it should have shown us about 50,000.     This time period happened to coincide with an unusually cool time span dubbed  "Europe's Little Ice Age."        Whether or not this was a correlation or causation is an issue that we have yet to have resolved.    It might well have been coincidental or, in fact, that long solar minimum did give the third world an unusual chill.      

Will our weather become a bit cooler now?  

Well, here along New England's upper rafters, we feel the urge to blame something for the winter chill that has insinuated itself into the many hours we called our "warm season."  Is it all related to a quiescent Sun?      If so, we can finally assign blame, even if we'd find it more problematic to exact revenge.