A recent peak in solar weather has helped a scientist discover cannibalistic tendencies among huge clouds of electrified gas ejected from the Sun.

Fast-moving clouds, known as coronal mass ejections (CME), have been found to collide with, overtake and devour slower-moving CME clouds in at least 21 instances recently identified by Catholic University of America researcher Natchimuthuk Gopalswamy. 

With the Sun in the midst of a period of intense activity that peaks every 11 years -- called the solar maximum -- scientists are poised to learn more about solar weather, including such phenomena as CMEs.

"Coronal Mass Ejection cannibalism is the most violent form of interaction between CMEs," said Gopalswamy, lead author of a research paper presented Tuesday during a meeting of the European Geophysical Society in Nice, France.

"This happens when a slow CME is expelled before a fast one from the same general region on the Sun. The fast CME simply gobbles up the slow CME, resulting in a single CME beyond the region of interaction."

The cosmic collisions also seem to create strange radio fireworks that Gopalswamy and his colleagues were able to link to images of the CMEs using the Solar and Heliospheric Observatory (SOHO) spacecraft. Along with the 21 collisions, dating back to April 1997, Gopalswamy and his colleagues suspect even more events that aren't detected because they are less energetic and do not produce a radio outburst.

"Collisions between CMEs may be more common than previously thought and may play a key role in determining the interplanetary traffic of CMEs," Gopalswamy said.

Solar eruptions directed toward Earth are potentially harmful to communications and power systems, and this cannibalistic behavior may result in longer magnetic storms. These collisions change the speed of the eruption, which is important for space weather prediction because it alters estimated arrival time of Earth-bound coronal ejections.

Gopalswamy, stationed at NASA's Goddard Space Flight Center in Maryland, presented the research with his colleagues from Goddard, Catholic University and the Naval Research Laboratory.

Coronal mass ejections are ejected from the Sun and hurled into space at speeds of 12 to 1,250 miles (20 to 2,010 kilometers) per second. Depending on the orientation of magnetic fields carried by the ejection cloud, Earth-directed eruptions cause magnetic storms by interacting with Earth's magnetic field, distorting its shape and accelerating electrically charged particles trapped within.

The researchers believe cannibal eruptions may be the source of "complex ejecta" CME clouds, larger and more complex in structure than typical eruptions. These traits cause complex ejecta CMEs to trigger protracted magnetic storms when they envelop Earth.

Severe solar weather is often heralded by dramatic auroral displays (northern and southern lights), but magnetic storms are occasionally harmful, potentially affecting satellites, radio communications and power systems. Understanding what happens to ejection clouds on their way to Earth is important in assessing their impact on the near-Earth space environment.

Observations from SOHO's Radio and Plasma Wave experiment revealed occasional intense bursts of emission originating far away from the Sun. When Gopalswamy and his colleagues were searching for the source of these radio outbursts, they discovered the ejection interaction, which produces high-energy electrons and causes the radio outbursts.

The astronomers expect an increased rate of ejection interaction during the solar maximum, because more ejections are expelled in quick succession at these times. During solar minimum, only one ejection per every other day is common; during maximum, several ejections occur in a day.

The cooperative SOHO project is part of NASA's and ESA's Solar Terrestrial Science Program (STSP), comprising of SOHO and CLUSTER. SOHO was launched Dec. 2, 1995. The SOHO spacecraft was built in Europe and instruments were provided by European and American scientists.

Kinks in the Sun's magnetic field have puzzled scientists since they first started studying the solar wind -- the extremely fast stream of particles that races constantly from the Sun. Now researchers at NASA's Jet Propulsion Laboratory in Pasadena, California have found the reason: They are caused by the evolution of a type of magnetic wave called Alfven waves.

Scientists measured sudden changes in the Sun's magnetic field with a magnetometer on the Ulysses spacecraft, which is orbiting the Sun's poles at a distance between Jupiter and Mars. Ulysses has been studying the Sun since 1990 and has just finished studying the south pole of the Sun at solar maximum.

"Over the poles of the Sun, we saw abrupt decreases in the magnetic field," said JPL's Bruce Tsurutani, a co-investigator on the magnetometer instrument on Ulysses. "We did not know what they were, because we had never seen anything like it before. Now we know that the disturbance is caused by Alfven waves."

Scientists expected to find that either the field magnitude remained the same, though the angle changed, or that the magnitude changed, with no fields threading across the structure, said Tsurutani. Instead, they found that the ends of Alfven waves always have both rotational and tangential characteristics.

Like the movements of a plucked guitar string, Alfven waves travel down the magnetic fields that emanate from the Sun. Disturbances in the Sun's magnetic field, which is embedded in the solar wind, travel through space to eventually cause auroras on Earth. The high-energy particles from the solar wind become trapped in Earth's magnetic field and come down into the atmosphere near Earth's north and south magnetic poles. The highly charged particles then collide with oxygen and nitrogen in Earth's atmosphere and emit light, forming the aurora.