Scientists say they found the earliest and most detailed signs of solar jet streams that will produce sunspots by about 1997, bolstering a theory that upsets traditional notions about the sunspot cycle.
"We're seeing the very earliest stage of the next sunspot cycle, not the one that is producing sunspots now, but that one that will produce them when this cycle is over," said astronomer Roger Ulrich of the University of California, Los Angeles.Ulrich and his colleagues were able to see the jet streams "at higher latitudes (on the sun) and earlier than we were ever able to before," said astrophysicist Herschel Snodgrass of Lewis and Clark College in Portland, Ore.
Snodgrass said understanding the sunspot cycle is important because the spots and related explosions called solar flares disrupt radar and radio and other communications on Earth and, in extreme cases, are believed to help spur ice ages and major droughts.
Ulrich said solar flares make Earth's outer atmosphere expand, so learning more about sunspots is important in deciding when to launch satellites, since atmospheric expansion produces orbit-altering drag on spacecraft.
Snodgrass said Ulrich's observation of the jet streams, which are east-west currents of gas parallel to the sun's equator, supports a theory developed independently by Snodgrass, Air Force astrophysicist Richard Altrock and California Institute of Technology astronomer Peter Wilson.
Last year, they proposed that the 11-year sunspot cycle during which the number of sunspots reaches a maximum, then a minimum and then another maximum is merely part of a previously unknown 18-to-22-year cycle that produces visible sunspots only during its last 11 years.
The theory says that during the earliest stages of this longer cycle, jet-stream-like gas currents appear near the sun's poles like smoke rings, which then "grow in size and roll down the outside of the sun toward the equator," Altrock said.
Only when the jet streams reach a solar latitude of 30 or 35 degrees about equivalent to Southern California do they produce sunspots, Ulrich said Tuesday by telephone from Tucson, Ariz., where he presented his findings Wednesday at a solar physics meetings.
He said he detected the jet streams at a latitude of 70 degrees on the sun, equivalent to northernmost Alaska.
"These jet streams eventually will migrate into the region where sunspots form," probably about 1997, Ulrich said.
"He's talking about the same phenomenon we have been talking about the outbreak of activity near the poles of the sun that takes 18 to 22 years to reach the equator," Altrock said by phone from Sunspot, N.M.