The concept, widely used as a rule of thumb by astronomers, was codified last year by Dr. Mendez and his colleagues into a more formal Habitable Zone Distance scale.

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Malcolm Turnbull, co-chairman of Goldman Sachs Australia (and founder of OzEmail, one of Australia's largest Internet providers), draws the distinction between north-south distance (same time-zone) and east-west distance (different time-zones).

ECONOMIST: Australian financial markets

Mr. AMOS GITAI (Director, Free Zone): From a distance, this conflict looks exotic or interesting, but once you get your neck into it, it is not easy.

NPR: Israeli Director Deconstructs a Troubled House