Making mirrors

Making mirrors

Tucson, Ariz. – A recipe for how to make an 8.4-meter telescope mirror: Ingredient: About 44,000 pounds of glass chunks. Instructions: Load glass chunks into 27-foot diameter mold. Place mold in giant spinning oven and set for five revolutions-per-minute. Cook...
The disappearing night sky

The disappearing night sky

Ian Cheney remembers when he first became interested in dark skies. He’d just moved from rural Maine to New York City and was amazed at how little of the night sky was visible. He could see celestial details in Maine, such as stars, planets, and the vast Milky...

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