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Counting the days since the last solar maximum

The Sun is not as steady as it appears. Roughly every eleven years, its surface churns with sunspots, flares, and coronal mass ejections before calming again. Scientists track this rhythm because the peak, known as the solar maximum, has tangible consequences for power grids, satellites, and the shimmering auroras that occasionally dance above Hobart and the southern coast of Australia.

For many curious skywatchers in Sydney, Perth, and regional Queensland, a natural question follows any major space weather event: how long has it been since the last solar maximum? Counting days from a specific date is a familiar exercise, the same kind of calculation people run for anniversaries, holidays, or the next full moon. The arithmetic is simple, but the story behind the number is rich.

This piece walks through the last solar maximum, the way to count the days that have passed, and what Australians can expect as the Sun climbs toward its next peak. Along the way, it points to a few tools that make the calendar work effortless, so readers can keep their own running tally without dusting off a calculator.

The rhythm of the solar cycle

The Sun cycles through periods of high and low magnetic activity. At the quiet end, the solar minimum, sunspots can vanish for weeks. At the busy end, the solar maximum, dozens of dark blemishes can pepper the photosphere in a single month. Each cycle lasts somewhere between nine and fourteen years, with eleven being a comfortable average.

Astronomers number cycles consecutively. Solar Cycle 1 began in 1755, which means the cycle that peaked in 2014 was officially Solar Cycle 24. Researchers at the Australian Space Agency and institutions like CSIRO follow the same numbering used by NASA and NOAA, so Australian observers can compare notes with colleagues anywhere on the planet.

When the last solar maximum took place

Solar Cycle 24 reached its peak in April 2014, with smoothed sunspot numbers hovering around 116. That made it one of the weaker maxima of the modern era, ranking among the quietest since Cycle 14 in the early 1900s. The months surrounding the peak, from late 2013 through mid-2014, were the most active stretch.

Counting forward from April 2014, the days accumulate steadily through the years, regardless of whether the Southern Hemisphere is basking in January sun or bracing for a July frost in Canberra. The total grows through three leap years, 2016, 2020, and 2024, before the next maximum arrives.

Working out the number of days

To find the days elapsed since 30 April 2014, subtract the earlier date from the later one and account for the leap years in between. 2016, 2020, and 2024 each added an extra day, and several more leap years will pass before the next maximum.

If today is in early 2026, the running total sits at roughly 4,300 days. Anyone who prefers not to do the math by hand can turn to a quick lookup on the calendar dates page, which handles the leap year juggling automatically and returns a clean integer ready for sharing.

What the Sun has been doing recently

Solar Cycle 25 is now well underway. Its activity began climbing in late 2019 and has surprised forecasters by running stronger than the official prediction panel expected. Sunspot counts have repeatedly crossed the levels seen during the previous peak, and several intense X-class flares have rippled through the inner solar system.

For Australia, that has meant more frequent geomagnetic storm warnings issued by the Bureau of Meteorology's space weather services. In May 2024, a series of powerful flares pushed the aurora australis so far north that photographers near Bendigo and even the Mornington Peninsula caught a pinkish glow on the horizon, a rare treat that had not been visible that far north in decades.

Pairing the count with lunar events

For a more focused skywatching session, it helps to coordinate with lunar events too. Bright moonlight can wash out faint auroral displays just as easily in the Kimberley as it does in Cornwall. A useful primer on Corn Moon insights explains how the harvest moons line up with the equinoxes and offers a few date calculations to keep handy.

Many Australians already keep tabs on upcoming astronomical events the way they plan around the AFL Grand Final or a long weekend in the Barossa. A bookmarked calendar page returns the answer in seconds and turns a fiddly subtraction into a one-click task.

Cycles worth comparing

A snapshot of recent solar maxima shows just how variable the Sun can be. Some peaks are sharp and stormy, while others are flat and mild. The figure below compares the smoothed peak sunspot number for the last four solar maxima, the year each peaked, and the approximate cycle length from minimum to minimum.

Solar cycle Peak year Smoothed sunspot number at peak Approximate cycle length (years)
21 1979 164 10.3
22 1989 158 9.7
23 2000 120 12.6
24 2014 116 11.0

The trend across these four cycles is a gradual decline in peak strength, which fits the longer quiet stretch observed during the early Space Age. Solar Cycle 25 looks set to break that pattern, at least modestly.

Looking ahead to the next peak

Forecasts for Solar Cycle 25 have been revised upward as the cycle matures. Current projections suggest the peak will arrive during 2024 or 2025, with a maximum sunspot number somewhere between 115 and 165. That would put the coming peak on par with, or slightly stronger than, the previous one.

For anyone counting days, the practical takeaway is that the next solar maximum is close. A quick check on a space weather bulletin can flag any incoming storms that might light up the night sky over the Bass Strait or the Nullarbor Plain. Once the peak arrives, the running tally resets, and a new count begins toward the cycle that will follow.

Signs that solar activity is climbing

Simple ways to follow the count

If the Sun has been on your mind lately, take a moment to calculate your own running total. A few seconds on a calendar lookup page will give you the exact number of days since 30 April 2014, and you can return any time the figure grows. When the next solar maximum arrives, the countdown simply begins again, ready for another decade of watching the sky.