27 Nov, 2020
JERUSALEM WEATHER

Earlier this month, a robotic satellite spotted a rare triple-comet flying past the sun. Scientists are unsure of the rare comet’s origins but it comes at a time when cosmic ray activity is on the increase in a manner that may have serious effects on the Earth’s climate.

Amateur astronomer Worachate Boonplod accessed the  Large Angle Spectrometric Coronagraph (LASCO) instrument of the Solar and Heliospheric Observatory (SOHO), launched by NASA and ESA, to catch sight of the triple comet on August 5. 

“It was a triple comet,” said Karl Battams of the Naval Research Lab in Washington DC. “The two main components are easy to spot, with the third, a very faint, diffuse fragment following alongside the leading piece.”

The triple-comet was unusual in that it was not a member of the Kreutz sungrazers family– fragments of a massive comet that shattered more than 1 000 years ago. Since the observatory launched 25 years ago, the satellite has discovered more than 3 000 members of the family. According to NASA, only about four percent or around 175 comets spotted by the satellite are not part of the sungrazers. Because of this anomaly, Battams said it is not yet clear where the comets came from.

“Unfortunately, the prognosis for small fragmenting comets like this is not good,” he stated. “This was probably this comet’s first and last pass by the sun, as it has likely now crumbled away entirely. But SOHO will continue to keep watching the sun, and waiting for our next special cometary offering to come along.”

The unusual sighting comes during a period of increased cosmic rays and decreased solar activity. Scientists believe the earth is entering just such a period known as a solar minimum

The solar cycle, or solar magnetic activity cycle, is a nearly periodic 11-year change in the sun’s activity measured in terms of variations in the number of observed sunspots on the solar surface. Accompanying the 11-year quasi-periodicity in sunspots, the large-scale dipolar (north-south) magnetic field component of the Sun also flips every 11 years. Solar activity can affect climate fluctuations on scales of centuries and longer.

Their non-linear character makes predictions of solar activity very difficult but it is believed that a solar maximum hit a peak of solar activity in 2014 ending in 2018. Some scientists believe we are now beginning a solar minimum that will reach its maximum in 2025. This is indicated by  2020 being the second consecutive year of a record-setting low number of sunspots.

The current minimum is forecasted to last longer than usual, just as it did in the previous solar cycle. Some researchers believe the upcoming solar minimum cycle could lower temperatures by as much as 0.3 degrees Celsius by 2025.

A recent study suggested that galactic cosmic ray (GCR) dose rates could increase by as much as 75 percent during the upcoming solar minimum. Earth’s magnetic field and atmosphere shields the planet from 99.9 percent of the radiation from space however, for people outside the protection of Earth’s magnetic field, space radiation becomes a serious hazard. No matter how much a spacecraft is shielded, it cannot stop the most energetic particles. This leaves astronauts exposed to danger whenever they leave the Earth-Moon system. This means that the number of time astronauts can safely work in interplanetary space will be limited as GCRs present a hazard for space missions.

Around three decades ago, astronauts could travel through space for as long as 1 000 days before hitting NASA safety limits on radiation exposure.

However, the new study notes that intensifying cosmic rays will limit space trips to only 290 days for male astronauts aged 45, and 204 days for females. Men and women have different limits because cosmic rays pose unequal dangers to reproductive organs.