May 02, 2018
from SpaceWeather Website
Sunspots are becoming scarce. Very scarce...
So far in 2018 the sun
has been blank almost 60% of the time, with whole weeks going by
without sunspots. Today's sun, shown here above in an image from NASA's
Solar Dynamics Observatory, is typical of the featureless solar
disk (above image).
The surprise is how fast.
This below plot shows observed sunspot numbers in blue vs. the official forecast in red:
"Official" forecasts of the solar cycle come from NOAA's Solar Cycle Prediction Panel - a group of experts from NOAA, NASA, the US Air Force, universities and other research organizations.
They have been convening at intervals since 1989 to predict the timing and intensity of Solar Max.
The problem is, no one really knows how to predict the solar cycle. The most recent iteration of the panel in 2006-2008 compared 54 different methods ranging from empirical extrapolations of historical data to cutting-edge supercomputer models of the sun's magnetic dynamo.
None fully described what
is happening now.
Sometimes they go away for decades, as happened during the Maunder Minimum of the 17th century.
We've seen it all before.
Or have we….?
The solar minimum of 2008-2009 was unusually deep. The sun set Space Age records for low sunspot number, weak solar wind, and depressed solar irradiance.
When the sun finally woke up a few years later, it seemed to have "solar minimum hangover."
The bounce-back Solar Max of 2012-2015 was the weakest solar maximum of the Space Age, prompting some to wonder if solar activity is entering a phase of sustained quiet.
decline of the sunspot cycle now may support that idea.
NASA recently launched a new sensor (TSIS-1) to the International Space Station to monitor this effect.
With less extreme UV
radiation coming from the sun, Earth's upper atmosphere cools and
shrinks. This allows space junk to accumulate in low Earth orbit.
A neutron bubble chamber in an airplane
35,000 feet above Greenland.
Spaceweather.com and Earth to Sky Calculus
are flying these sensors to measure
aviation radiation during solar minimum.
Flagging solar wind pressure during solar minimum allows cosmic rays from deep space to penetrate the inner solar system. Right now, space weather balloons and NASA spacecraft are measuring an uptick in radiation due to this effect.
Cosmic rays may alter
the chemistry of Earth's upper atmosphere, trigger lightning,
and seed clouds.
Passengers on long commercial flights receive doses similar to dental X-rays during a single trip, while pilots have been classified as occupational radiation workers by the International Commission on Radiological Protection (ICRP).
Ongoing measurements by
Earth to Sky Calculus show that
dose rates at cruising altitudes of 35,000 feet are currently ~40
times greater than on the ground below, values which could increase
as the solar cycle wanes.