TULSA, Oklahoma - Keep your eyes open for the northern lights tonight, if the weather cooperates.

Astronomers say a sunspot erupted on Thursday, sending a coronal mass ejection toward Earth.  

Originally the experts at spaceweather.com expected the cloud of energy to arrive here Saturday, January 21, 2012.  But now they say it's begun arriving on Sunday and appears to be getting stronger.

People in the northern latitudes are reporting a spectacular demonstration of the aurora borealis, also known as the northern lights, but there's a chance people living farther south could see the phenomenon, too.

Auroras form when the sun sends charged particles into Earth's magnetic field.  

The solar wind as it's called accelerates electrically-charged particles trapped in the magnetic field and then crashes into Earth's upper atmosphere over the poles, causing the atmosphere to glow in vibrant colors.

The northern lights are rarely visible as far south as Oklahoma, but they were visible in the state last October.

There's no guarantee they'll be visible in Oklahoma this time around, but as of late Sunday afternoon the northern hemisphere was aglow with a very active aurora borealis.  

Keep an eye on the northern sky just above the horizon any time after sunset Sunday.  Try not to be disappointed if they're not visible this far south.