David Hathaway, head of the solar physics group at NASA’s Marshall Space Flight Centre reports that solar activity is “the weakest in 200 years”. “There is no scientist alive who has seen a solar cycle as weak as this one,” reports Andrés Munoz-Jaramillo of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. Puzzled scientists are witnessing the sun’s oddest magnetic reversals on record.
Normally, the sun’s magnetic north and south poles change polarity approximately every 11 years. During a magnetic-field reversal, the sun’s polar magnetic fields weaken, drop to zero, and then emerge again with the opposite polarity. Douglas Biesecker at NASA’s Space Environment Center says that “the magnetic shift is notable only because it signals the peak of the solar maximum”. However this cycle the sun’s north magnetic pole reversed polarity more than a year ago, so it has the same polarity as the south pole.
“The delay between the two reversals is unusually long,” said solar physicist Karel Schrijver at the Lockheed Martin Advanced Technology Center in Palo Alto, Calif.
Scientists said they are puzzled, but not concerned, by the unusual delay. They expect the sun’s south pole to change polarity next month, based on current satellite measurements of its shifting magnetic fields.
Recently there has been an unexplained scarcity of sunspots. “It is not just that there are fewer sunspots,” says Dr. Schrijver, “But they are less active sunspots.” However, after months of quiescence, the sun has recently unleashed vast streams of charged particles into space five times in as many days last month, and flared again last week. Even so, these outbursts exhibited a fraction of the force of previous solar maximums.
Here are some photos by our member Bob Evermon, taken from his Skywatch from May 8 and June 23rd.