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Sun's low magnetic activity may portend an ice age


Frost fair on the Thames, 1683

The Canadian Space Agency's radio telescope has been reporting Flux Density Values so low they will mean a mini ice age if they continue, according to CSA project director Ken Tapping with whom we just spoke.

Like the number of sunspots, the Flux Density Values reflect the Sun's magnetic activity, which affects the rate at which the Sun radiates energy and warmth. Tapping calls the radio telescope that supplies NASA and the rest of the world with daily values of the Sun's magnetic activity a "stethoscope on the Sun". In this case, however, it is the "doctor" whose health is directly affected by the readings.

According to NASA, "early, well-documented records indicate that the Sun went through a period of inactivity in the late 17th century" from about 1645 to 1715, during the Maunder Minimum.

"This period of solar inactivity also corresponds to a climatic period called the Little Ice Age when rivers that are normally ice-free froze and snow fields remained year-round at lower altitudes." It was called the Maunder Minimum, after Edward Maunder, a British accountant who saw a sunspot "like a tack in the Sun" while he was walking home, and subsequently made counting and analyzing sunspots, rather than money, his life's work. There have been other Minimums. The Dalton Minimum of 1800 to 1810 was that period when Napoleon had his unfortunate encounter with the Russian winter.

This is because when the magnetic activity is low, the Sun is dimmer, and puts out less radiant warmth. If the Sun goes into dim mode, as it has in the past, the Earth gets much colder.

Tapping, who was originally from Kent, says that "Typically as you go through the ten or eleven year solar activity cycle you see the numbers go up or down. The lowest number is 64 or 68. The numbers 71 or 72 are very low, but they usually start to go up. We are at the end of a cycle, but the numbers still haven't gone up. We have been joking around coffee that we may be seeing the Sun about to shut down." (To date Tapping has been far more concerned about global warming.)

These were the values released yesterday -

Density Values in sfu for 22:00 on 2008:01:30

Julian Day Number : 2454496.406

Carrington Rotation Number : 2066.207

Observed Flux Density : 0073.6

Flux Density Adjusted for 1 A.U. : 0071.4

URSI Series D Flux, Adj. x 0.9 : 0064.3

Daily updated values are here.

If the Sun's magnetic activity does not increase, and it goes dim for an extended period, it will get quite chilly. In the meantime the Canada Space Agency, the Royal Observatory Greenwich and the US Air Force Solar Optical Observing Network are all keeping an eye on the Sun.