A scanner darkly.(Letter to the editor)

Dr. Weaver,

In your March 2007 column, you state: "It is actually two clusters of galaxies, gasses and plasma found about four billion light years from Earth that collided around 100 million years ago."

Isn't there a typing error in this sentence? It seems to not make sense to see an event that happened 100 million years ago if the two clusters in question are four billion light years away from the Earth. I appreciate your kind response.

VICTORIO

ANALYTICAL TECHNOLOGIES S.A.

Hi Victorio,

I wrestled with this as w