The rocket carrying the Solar Terrestrial Relations Observatory, or Stereo - a pair of solar probes - lifted off from Cape Canaveral Air Force Station in Florida on Wednesday.
Stereo will take pictures of the solar outbursts so that scientists can, for the first time, pinpoint where the storms are heading.
The eruptions, called coronal mass ejections, can shut down communications and navigational satellites, affect aircraft and disrupt electricity supplies as billions of tonnes of charged particles are sent streaming into space.
"Right now we can only see the Sun, essentially, in just two dimensions," said Terry Kucera, Stereo's deputy project scientist. "We can't tell in some cases whether coronal mass ejections are moving towards us or away from us. That's pretty fundamental.
Part of one of the solar probes
during assembly (Nasa)
"With 3-D, we'll be able to tell basic things like how fast is it going, is it speeding up or slowing down?
"These are important things that we need to know if we're going to be able to predict what the impact of a particular event is going to be."
The satellites were launched on a Boeing-built Delta rocket, which lifted off at 8:52pm local time (0052 GMT).
They were placed in a temporary, looping orbit around the Earth. On December 15, lunar gravity will slingshot the first spacecraft into a solar orbit just ahead of Earth's path.
The second satellite will be flung into an orbit lagging Earth on January 21. From the perspective of the Sun, the spacecraft will orbit 45 degrees apart, providing enough distance to work like a pair of human eyes that can see in three dimensions.
The transport cannister will carry
both probes into orbit (Nasa)
A massive solar storm in 1989 damaged a power grid in Canada, shutting off electricity for six million residents. Three years ago, Japan lost contact with a satellite after a series of solar eruptions.
"In terms of space-weather forecasting, we're where weather forecasters were in the 1950s," said Michael Kaiser, a Stereo project scientist. "They didn't see hurricanes until the rain clouds were right above them."
Stereo: The Sun in 3D - Nasa official mission site