Heading to Solar Minimum

Sunspot numbers continue to decline as 2017 begins.


One of the biggest sunspot groups of cycle 24 added extra interest to the October 23, 2014, partial solar eclipse. Courtesy Gary Seronik

In June 2016, the solar disc was completely free of sunspots for more than two days in a row for the first time since 2011. That 2016 spotless stretch lasted twelve days from the end of June to early July before a sunspot finally appeared. In all, the face of the Sun was blank for 32 days 2016. And yet, before the first month of 2017 was half over, there had already been 10 days without sunspots. Clearly, we’re well on our way to solar minimum.

Blank Sun - June 27, 2016

A spotless Sun, as imaged on June 27, 2016, by Gary Seronik.

The Sun undergoes an 11-year cycle, during which the number of sunspots climbs to a maximum before settling down for solar minimum. Not all cycles are alike, and the current one (cycle 24) has been very odd. Not only was the maximum unusually weak, the cycle exhibited a rare double peak—something that hasn’t happened since 1906.

Sunspot numbers

Courtesy Sunspot Index and Long-term Solar Observations/Royal Observatory, Belgium

Sunspot numbers have been gradually declining since cycle 24 reached its second, largest peak in April 2014. And because sunspots are a good indicator of general solar activity, the low numbers mean displays of northern lights are also becoming less and less frequent.

Ian Barredo-Aurora

This spectacular “selfie” was taken by Ian Barredo on the hills of Pasqua Lake in Saskatchewan in July 2015 when the aurora was peaking almost every night.

Of course, there will be many peaks and valleys within in the overall trend before solar minimum occurs in roughly four years. So if you’re a solar observer or aurora watcher, don’t give up hope just yet—there’ll be plenty of interesting days (and nights) ahead. They’ll just happen less often.

Categories: Observing the Sky
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