New research from the U.S. National Aeronautics and Space Administration (NASA) predicts that the next decade will be a favorable period for human exploration due to lower risks of inclement "space weather"—a term that refers to radiation conditions in Earth's vicinity, determined mostly by solar activity. Similar to terrestrial weather, space weather is variable, thanks to the Sun's inconstant state. Our star naturally goes through a roughly 11-year cycle of waxing and waning activity, marked by observable numbers of sunspots. These dark blots on the Sun's surface serve as indicators of localized magnetic field strength. Sunspots are associated with bursts of energy known as solar flares, as well as eruptions of solar plasma into space called coronal mass ejections. Such outbursts hurl radiation toward our planet that, on the one hand, can benignly trigger brilliant auroral displays in the atmosphere. On the other hand, extreme space weather can wreak havoc by damaging satellites and posing health hazards to astronauts by increasing their lifetime risk of cancer. Thus, the new research results bode well for NASA’s ongoing effort to return humans to the Moon for the first time since 1972. See also: Astronautics; Astronomy; Aurora; Cancer; Electromagnetic radiation; Plasma (physics); Radiation; Radiation damage to materials; Radiation injury to plants and animals; Satellite (spacecraft); Solar corona; Space flight
The Sun's next solar cycle is expected to begin this year or in 2020 with a solar minimum, or lowest sunspot count. According to the new research, even this next cycle's solar maximum—when sunspot counts will peak, circa 2025—should be mild compared to historical standards, with sunspot totals running about 30 to 50% lower than the last cycle's maximum. Overall, the research points to the next solar cycle being the weakest in approximately two centuries, almost back to when recordkeeping of sunspots began in earnest in the mid-18th century. See also: Sun
To arrive at these estimates, the new research from NASA’s Ames Research Center in California started with data from two space telescopes dedicated to monitoring the Sun: the Solar and Heliospheric Observatory (SOHO) and the Solar Dynamics Observatory (SDO). The spacecraft launched in 1995 and 2010, respectively. Those instruments' logs of observations were paired with the records of the New Mexico–based National Solar Observatory, which has kept watch over the Sun since 1976. See also: Solar and Heliospheric Observatory; Solar Dynamics Observatory
Most solar weather forecasting has relied on anticipated sunspot numbers to indirectly account for solar magnetic activity. The new research instead took the approach of using observations of magnetic fields emanating from the Sun's surface—a kind of measurement only available since the National Solar Observatory's debut more than four decades ago. Researchers first started combining these data streams in 2008 and fed them into the latest models of the Sun's interior workings and their relation to external solar manifestations. The resulting prediction of solar activity aligned closely with the previous solar cycle's output. The accuracy of that prediction has thus instilled confidence in the newest prognostication of an attenuated solar cycle lasting through the 2020s. Nevertheless, space weather forecasting remains a challenging endeavor with high degrees of variability and unpredictability, similar to terrestrial weather forecasting, and researchers will continue to hone their models further with each passing solar cycle. See also: Solar magnetic field
