A National Atmospheric and Oceanographic Administration satellite recorded the flare at 3:48 a.m. EDT, a NASA release said.
"It was a big flare," Joe Kunches, a space scientist with NOAA's Space Weather Prediction Center told SPACE.com. "We lucked out because the site of the eruption at the sun was not facing the Earth, so we will probably feel no ill effects."
The flare was rated a class X6.9 on the scale scientists use to compare solar flares, where class X is the strongest, class C the weakest and class M flares are those of medium strength.
X-class solar eruptions release a cloud of plasma called a coronal mass ejection into space.
If aimed at Earth the ejections can bombard the planet with charged particles that can disrupt the atmosphere and interfere with GPS and communications signals.
Radiation from solar flares can be strong enough to affect humans in space if they do not protect themselves, NASA said.