The Solar Minimum is Here
The sun is coming to the end of its current cycle. It’s experiencing something called the “solar minimum” when there are fewer sunspots present on the surface of the sun — even zero some days. But what does the end of a solar cycle mean for those of us on earth? (1)
According to NASA, the sun goes through regular 11-year cycles. During those years, the sun’s energy output changes. Scientists can measure these changes through the number of sunspots on its surface. The time when the sunspots are highest is called a “solar maximum”. When the sunspots decrease the most is called the “solar minimum”. (1, 2)
Sunspots are highly magnetized areas on the sun. They look like dark spots (although you should never look directly at the sun). Scientists have counted them every day since 1838. Keeping track of the number of sunspots allowed them to notice the pattern that makes up the solar cycle. (1, 3)
The most recent solar maximum occurred in 2014. Since then, the number of sunspots has been decreasing, and scientists have expected the solar minimum to happen in 2019 or 2020. (1)
No Cause for Alarm
Some have been concerned that this means that a mini ice age is coming. But NASA quickly put that fear to bed, saying that it’s just not happening. (2)
Sometimes there are prolonged periods of low solar energy, called “Grand Solar Minimums”, such as the “Little Ice Age” that occurred from 1650 to 1715 AD. A longer period of low solar activity happened at the same time as cooling from volcanic aerosols. This resulted in lower surface temperatures for those 65 years. (2)
The solar maximum that happened in 2014 has been considered relatively weak. Because of this, some scientists have predicted another Grand Solar Minimum in the coming decades. (2, 3)
It’s unclear whether or not this will happen, but if it does, NASA argues that global warming would essentially cancel it out. According to the agency’s website, “The warming caused by the greenhouse gas emissions from the human burning of fossil fuels is six times greater than the possible decades-long cooling from a prolonged Grand Solar Minimum.” (2)
So even if a Grand Solar Minimum lasted for 100 years, global temperatures would continue to rise. The sun’s energy output isn’t the only thing that determines the temperature on earth. The Grand Solar Minimum in the 17th and 18th centuries coincided with another factor (cooling from volcanic aerosols) to cause the Little Ice Age. Basically, this isn’t our greatest concern. (2)
Effects of Solar Minimum
So what does happen during a period of decreased solar energy? The effects are mostly seen in space. For instance, changes in space weather effects cause the number of galactic cosmic rays that reach Earth’s upper atmosphere to increase. (1)
Dean Pesnell of NASA’s Goddard Space Flight Center says that “During solar minimum, the sun’s magnetic field weakens and provides less shielding from these cosmic rays. This can pose an increased threat to astronauts traveling through space.” (1)
We may not observe the immediate effects of a solar minimum here on earth. But the impacts on space and the sun itself are fascinating.
