Something interesting is happening on the sun. On June 3rd, the sunspot number dropped to 0, and the solar disk is still blank three days later. Latest images from NASA's Solar Dynamics Observatory reveal no significant dark cores:
What does this mean? The solar cycle is like a pendulum, swinging back and forth between periods of high and low sunspot number every 11 years. Today's blank sun is a sign that the pendulum is swinging toward low sunspot numbers. In other words, Solar Minimum is coming.
The spotless state of today's sun is just temporary. Underneath the visible surface of the sun, the solar dynamo is still churning out knots of magnetism that will soon bob to the surface to make new sunspots. The current solar cycle is not finished. It is, however, rapidly waning.
Forecasters expect the next Solar Minimum to arrive in 2019-2020. Between now and then, there will be lots of spotless suns. At first, the blank stretches will be measured in days; later in weeks and months. Don't expect space weather to grow quiet, however. Solar Minimum brings many interesting changes. For instance, as the extreme ultraviolet output of the sun decreases, the upper atmosphere of Earth cools and collapses. This allows space junk to accumulate around our planet. Also, the heliosphere shrinks, bringing interstellar space closer to Earth. Galactic cosmic rays penetrate the inner solar system with relative ease. Indeed, a cosmic ray surge is already underway. Goodbye sunspots, hello deep-space radiation!
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