CME – coronal mass ejection: a burst of solar winds, plasma and magnetic fields released into space. Not the same as a solar flare.

Lightyear (ly) – As defined by the International Astronomical Union: the distance that light travels in a vacuum in one Julian year.

MECO – main-engine cutoff, the point at which a space craft's main engines stop firing.

Stringer – A vertical strip of metal, 108 of which surround the Shuttle's external tank and provide structural support.

SRB – solid rocket booster, one of the twin rockets that flank the space shuttle and provide extra thrust to achieve orbit.