A monster flare has exploded from the sun, triggering a high-speed space storm that could play havoc with satellites, radio communication and power grids, scientists said yesterday.

The off-the-charts eruption was the most intense in more than a quarter-century, a spectacular volcano that rocketed a massive bubble of high-energy plasma into the solar system.

“The storm right now is extreme, but its location may save us,” said Larry Combs, a space-weather forecaster for the National Oceanic and Atmospheric Administration.

The sun belched out the super-flare from its northwest edge on Monday. If it had happened two days earlier, the cloud of electrified gas would have been aimed directly at Earth.

Satellites are the most vulnerable targets of solar flares. Atmospheric drag can slow or pull them down, and highly charged electrons can bombard and degrade their solar panels.

Radio signals also are at risk for scrambling. The practical effects include static on high-frequency radios used by boats and planes, glitches in cell-phone and pager service, commercial TV and radio disruptions and inaccuracies in global-positioning systems.