The 11-year solar cycle continues during prolonged sunspot minima

November 13, 2012
Image of sun courtesy of NASA.

Streaming into the solar system at nearly the speed of light, galactic cosmic rays (GCRs) are a high-energy mix of protons, electrons, and atomic nuclei. As they pass into reach of the outflowing solar wind, the propagation of GCRs is inhibited. Galactic cosmic rays that make it to Earth interact with the atmosphere, creating a shower of heavy isotopes including beryllium-10. Beryllium-10 isotope concentrations recorded in ice cores provide a long-term, high temporal resolution record of galactic cosmic ray flux.

The rate of GCRs flowing into the solar system is thought to be relatively stable, so researchers suspect that shifts in these long-term isotope records must be driven by a change in the rate at which GCRs reach Earth. The propagation of GCRs to Earth, in turn, depends on the open solar flux, the fraction of the total that is carried out into the solar system by the solar wind. Open solar flux increases with sunspot number and shifts with the orientation of the heliospheric current sheet, the wavy surface where the Sun's the magnetic field switches polarity from northward to southward. Thus isotope concentration records can serve as a long-scale record of solar activity.

Drawing on two independent ice core records, Owens et al. modeled the open solar flux back to 1610, a period that includes the , a 65-year stretch starting in 1650 when astronomers observed hardly any sunspots. They find that during this period, beryllium-10 isotope concentrations continued to oscillate following the roughly 11-year solar cycle, despite the dearth of sunspots. They suggest that the heliospheric current sheet's cyclical behavior didn't change during the period, and hence the regular cycling of the open , and the changing penetration of , continued.

Explore further: How Strongly Does the Sun Influence the Global Climate?

More information: Heliospheric modulation of galactic cosmic rays during grand solar minima: Past and future variations, Geophysical Research Letters, doi:10.1029/2012GL053151 , 2012

Related Stories

How Strongly Does the Sun Influence the Global Climate?

August 2, 2004

Studies at the Max Planck Institute for Solar System Research reveal: solar activity affects the climate but plays only a minor role in the current global warming Since the middle of the last century, the Sun is in a phase ...

Cosmic Rays Hit Space Age High

September 29, 2009

( -- Planning a trip to Mars? Take plenty of shielding. According to sensors on NASA's ACE (Advanced Composition Explorer) spacecraft, galactic cosmic rays have just hit a Space Age high.

Explaining the mystery of the missing sunspots

April 5, 2011

Sunspots have been observed for about four centuries, since they were first reported by Galileo. Appearing in roughly eleven-year cycles of activity, sunspots are regions of strong and complex magnetic fields which are also ...

Cosmic rays alter chemistry of lunar ice

March 19, 2012

Space scientists from the University of New Hampshire and multi-institutional colleagues report they have quantified levels of radiation on the moon's surface from galactic cosmic ray (GCR) bombardment that over time causes ...

Solar 'climate change' could cause rougher space weather

April 2, 2012

( -- Recent research shows that the space age has coincided with a period of unusually high solar activity, called a grand maximum. Isotopes in ice sheets and tree rings tell us that this grand solar maximum is ...

Recommended for you

Earth might have hairy dark matter

November 23, 2015

The solar system might be a lot hairier than we thought. A new study publishing this week in the Astrophysical Journal by Gary Prézeau of NASA's Jet Propulsion Laboratory, Pasadena, California, proposes the existence of ...

The hottest white dwarf in the Galaxy

November 25, 2015

Astronomers at the Universities of Tübingen and Potsdam have identified the hottest white dwarf ever discovered in our Galaxy. With a temperature of 250,000 degrees Celsius, this dying star at the outskirts of the Milky ...

Scientists detect stellar streams around Magellanic Clouds

November 23, 2015

(—Astronomers from the University of Cambridge, U.K., have detected a number of narrow streams and diffuse debris clouds around two nearby irregular dwarf galaxies called the Magellanic Clouds. The research also ...


Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (3) Nov 14, 2012
"the fraction of the total solar magnetic field that is carried out into the solar system by the solar wind."

I'm curious how they propose that the solar wind "carries" magnetic fields.
1 / 5 (4) Nov 14, 2012
So, if the particles are charged, and by definition, an electric current is a flow of electric charge through a conductive medium, wouldn't the electric current create it's own magnetic field?

Much confusion is induced among many with their skewed analogies of how these processes take place.

"Students using astrophysical textbooks remain essentially ignorant of even the existence of plasma concepts, despite the fact that some of them have been known for half a century. The conclusion is that astrophysics is too important to be left in the hands of astrophysicists who have gotten their main knowledge from these textbooks. Earthbound and space telescope data must be treated by scientists who are familiar with laboratory and magnetospheric physics and circuit theory, and of course with modern plasma theory." — Hannes Alfvén

The solar wind is itself an electric current within the Sun's radial electric field. Such a realization can explain the unexpected accelerating solar wind.
not rated yet Nov 14, 2012
Wow Nat! Watts site posted something of use...too bad he tried to use it the way he did at the end of the article. Planetary position effects all stars, this is our primary mode of planetary detection. It would be rediculous to assume that the only effect is a visible oscillation. CD85, you know what their intended meaning was.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.