The zodiacal dust bands were discovered by the Infrared Astronomical 
Satellite (IRAS). They form pairs of bright infrared (IR) emission strips 
that run along the ecliptic. Two of the three identified dust bands, known 
as beta and gamma, were previously linked to the recent asteroid 
breakups that produced groups of asteroid-sized fragments, so-called 
asteroid families, near orbits of (832) Karin and (490) Veritas. The 
origin of the third, near-ecliptic alpha dust band has been unknown 
until now. Here we report a discovery of a recent breakup of a 
>20-km-diameter asteroid near the alpha band's originally suspected 
source location in the Themis family. Numerical modeling and our new 
Spitzer observations of the alpha-band thermal emission allowed us to 
show that the discovered breakup is the source of alpha-band dust 
particles. This result has important implications for our understanding of 
the contribution of asteroid sources to the zodiacal cloud and the origin 
of circumstellar debris disk in general. It may also help to explain the 
observed cometary activity of asteroid (7968) Elst-Pizzaro because this 
object, one of the identified fragments of the recent breakup in the 
Themis family, is probably unusually young.