This story is a reminder that our sun is a variable star whose dynamic production of magnetism, activity and winds have implications for our planet.
Solar magnetic fields power solar activity, including sunspots, explosive events known as solar flares and coronal mass ejections, and an outward-flowing solar wind.
The sun’s activity and wind bathes Earth in a changing space environment of high-energy radiation and fast-moving particles called “space weather”. This gives us both the beauty of the aurorae and disruptive effects on communications and other technology.
Solar activity varies over time, with the 11-year sunspot cycle being the most familiar example. Solar activity also varies more widely over longer timescales, producing “grand maxima” and “grand minima”.
The current rate and extent at which solar activity is falling has been interpreted as the beginning of another grand minimum, and raises the issue of what it means for Earth’s climate.
Variations in solar activity have long been linked to climate variability on Earth, with the most familiar historical example being the Maunder minimum. This corresponded to relatively cold climatic conditions described as the “Little Ice Age” when rivers that were normally ice-free froze and snow fields remained year-round at lower altitudes.
Question of how solar activity influences the Earth’s climate remains the subject of ongoing research. What is becoming clearer is that variations in solar ultraviolet radiation resulting from solar activity can provide a physical mechanism for the Sun to influence the Earth’s atmosphere.
However, it is important to understand that research also indicates that these solar effects are minor compared to modern-day anthropogenic effects. Even if there is measurable cooling, a grand minimum should not be relied upon to slow global warming.
Climatic effects aside, a grand minimum in solar activity would mean reduced auroral displays, and some lessening of the hazards caused by space weather for spacecraft, and any occupants.
Why the fluctuations?
The answer lies in how the sun generates its magnetic field.
As a typical star our sun is a ball of hot gas, more than a hundred times the diameter and hundreds of thousands of times more massive than the Earth.
Inside the sun, the effects of heat, pressure and motion produce electrical currents that in turn generate magnetic fields. This solar dynamo results in magnetic fields emerging from the sun’s visible surface to power its activity and winds and the space weather experienced by Earth.
Explaining the variable nature of solar activity comes down to understanding the physics of the solar dynamo. At present there is a general theoretical picture of how the dynamo can produce magnetic fields and even cycles.
What is less certain is how the dynamo changes into the special state that corresponds to grand minimum, and whether such occurrences are to some extent predictable or purely random.
One way to learn more about the sun and its dynamo is to study other stars. Dynamos occur in many other stars, so observations of stars of different ages can offer clues regarding the past and future of solar magnetism and its effects. These magnetic studies of stars and their activity and winds can be used to better test the predictions of dynamo theory.
An improved understanding of stellar dynamos may then help us know more about what is happening to the sun today, and perhaps provide a useful tool to forecast future changes in our variable sun.
Are Antibiotics Leading To An Increased Risk Of Miscarriage?
According to a new study published in the CMAJ (Canadian Medical Association Journal), many classes of antibiotics are associated with an...May 1, 2017
Could a Carbon Tax Work?
Over the past couple of years, several suggestions for limiting the amount of greenhouse gases that are produced by the burning...May 1, 2017
Genes Might Be Helping the Tasmanian Devil Fight Off Face Cancer
Getty Images The Tasmanian devil is famous for two things. One, it’s ornery as all hell. And two, it’s the unfortunate...August 30, 2016
How to Use Physics to Paddle Board Like a Pro
Getty Images Question: How do you make a stand up paddle board go straight if you only paddle on one side?...August 29, 2016
Cluster of Big Earthquakes Rattles Iceland’s Katla Volcano
Alamy Last night, a brief earthquake swarm rattled the caldera at Katla in southern Iceland. The largest earthquakes were over M4,...August 29, 2016
Six Scientists Lived in a Tiny Pod for a Year Pretending They Were on Mars
Arguably one of the most Mars-like environments on Earth, the north side of Mauna Loa has been home sweet home to...August 29, 2016
Forget the Pool. This Guy Chased Tornadoes All Summer
This May, a massive supercell storm ripped through the countryside just outside of Dodge City, Kansas. It produced more than a...August 29, 2016
This Aquanaut Is Defining the Next Era of Spaceflight
NASA Megan McArthur has spent her life messing with microgravity. She was on the team that got the first commercial cargo...August 29, 2016
What Gives With Insects Pretending to Be Sticks and Leaves?
Imagine that you had one outfit and one outfit only: a jumpsuit that made you look like a leaf. You’d blend...August 29, 2016