New Mexico's largest electric provider — the coal-fired San Juan Generating Station near Farmington — has been defending a plan to replace part of an aging coal-fired power plant with a mix of more coal, natural gas, nuclear and solar power. Susan Montoya Bryan/AP hide caption

toggle caption Susan Montoya Bryan/AP

The moon is one of the most obvious natural indicators that the passing of time follows a pattern and can be tracked in a useful way. Bill McKelvie/ hide caption

toggle caption Bill McKelvie/

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