Because the CHZ is considered the most likely habitat for intelligent life , METI efforts have also been focused on systems likely to have planets there . The 2001 Teen Age Message and the 2003 Cosmic Call 2 , for example , were sent to the 47 Ursae Majoris system , known to contain three Jupiter-mass planets and possibly with a terrestrial planet in the CHZ . The Teen Age Message was also directed to the 55 Cancri system , which has a gas giant in its CHZ . A Message from Earth in 2008 , and Hello From Earth in 2009 , were directed to the Gliese 581 system , containing three planets in the CHZ — Gliese 581 c , d , and the unconfirmed g
Teen Age Message
Teen Age Message
Circumstellar habitable zone