Updated September 1, 2019: See the BOLD print below for the latest.
Has anyone noticed anything different about the Sun? Anything unusual? Well, there’s nothing different, nothing unusual. The Sun is just going through its normal cycle. So, if you’ve looked lately, you’ve probably noticed that Sunspots are becoming rarer. The Sun goes through cycles. These cycles are measured by the number of Sunspots seen on the Sun’s surface, that is, the Earth-facing side. Each cycle lasts for about 11 years, with slight variations of time in each cycle.
The solar cycle was discovered in 1843 by Samuel Heinrich Schwabe, and using other observations, reconstructed the cycle back to 1745. Prior cycles were reconstructed from observations going back as far as Galileo and others in the early 1600’s. We are presently in cycle 24. Right now, the Sunspot number is decreasing, and it has been for some time. Let’s look at the numbers.
Cycle 24 peaked in April, 2014 with 101 Sunspots, the weakest in a hundred years. There was only 1 day in 2014 with no Sunspots. 2015 had 0 spotless days. 2016 had 32 spotless days. 2017 had 104 spotless days.
At the end of 2018, there were 221 total spotless days, yielding a yearly percentage of 61%. The Sun produced a small group of Sunspots on the first day of 2019, and they rotated all the way around the Western limb of the Sun. All of February was spotless. We have now had 169 total spotless days, yielding a 2019 yearly percentage of 69% so far. A 24 day spotless stretch ended today with a small group of 11 small spots.
Sunspots have a magnetic North and South Pole. The poles align with the Sun’s equator. Every solar cycle, the Sun’s poles reverse, as do the sunspot’s poles. On March 5, a small magnetic disturbance started to appear and was oriented perpendicular to the Sun’s equator. The pole of one sunspot in January was oriented opposite to the Sun’s poles. This wasn’t the first, so does this mean that the poles are about to reverse and usher in a new solar cycle (cycle 25)? Maybe. But these latest to appear have the cycle 24 polarity.
But even with this minimum, there is still activity to be observed. There is still the frequent small prominence, flare or CME (Coronal Mass Ejection). And then there are the “holes” in the Sun’s atmosphere (coronal holes) that let stronger than normal streams of solar wind (charged particles), target the Earth’s atmosphere and produce those awesome auroras in the high latitudes. Lately, auroras have been seen in the upper US states. So if you have a solar telescope, keep watching, it’s not hopeless.
Keep checking back, we’ll keep you updated.