The flare flew out into space on Tuesday, unleashing radiation on a level not seen since 2006. It created a large cloud that appeared to cover almost half the surface of the sun, NASA said.
The resulting geomagnetic storm could cause minor disruption in power grids, satellites that run global positioning systems and other devices late Wednesday or early Thursday.
Scientists say it could also force pilots to reroute flights over the polar areas.
"This wasn't really such a big event," said Michael Hesse, chief of the space weather laboratory at NASA's Goddard Space Flight Center in Greenbelt, Md. "It was spectacular to watch, but not big in terms of hazards to the Earth."
A much larger solar flare erupted Saturday, but NASA didn't capture images because it happened on the side of the sun opposite Earth, Hesse said. Scientists have been expecting an increase in solar activity because the sun is moving into a more volatile period of an 11-year cycle in which its magnetic field reverses its orientation.
"The sun has woken up and is becoming more active as we approach the solar maximum," expected in 2013, Hesse said.
The Associated Press contributed to this report.