“Planet in Peril” (9 p.m., CNN): “Planet in Peril” is a two-night news

“Planet in Peril” (9 p.m., CNN): “Planet in Peril” is a two-night news documentary focusing on four key issues that threaten the world’s environment and its inhabitants: climate change, deforestation, species loss and overpopulation. Anderson Cooper reports, along with Dr. Sanjay Gupta and Animal Planet wildlife biologist Jeff Corwin.

“Showdown With Iran” (9 p.m., PBS): PBS’s “Frontline” series looks at the growing threat of Iran, including the troubled history the country has had with the United States.

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Damages” (10 p.m., FX): Rabid fans of this mind-blowing murder mystery will at last get the answers they crave when the show wraps up its remarkable first season. That means the legal grudge match between driven attorney Patty Hewes (Glenn Close) and powerful business tycoon Arthur Frobisher (Ted Danson) will finally culminate and we’ll learn whether Patty is a cold-hearted snake or just misunderstood. The summer gave us plenty of extraordinary cable programming and “Damages,” with its twisty plots, solid writing and brilliant cast, has ranked at or near the top of the list. The finale hints at a Season 2 story line, but as of this writing, “Damages” had yet to be renewed.