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What you can see on fee-free days at U.S. national parks this year

Listen to this pug and you'll understand why the makers of 'Halo' hired him for voice-overs

What you need to know about that mysterious Chinese virus

Our moon is more colorful than you think

Mysterious blind 'ghost fish' reveals Congo to be the deepest river in the world

What lies beneath the Antarctic ice sheet?

Do black holes have friends?

Diego the giant tortoise has dedicated himself to the survival of his species

Teen interning at NASA discovers new planet

Australian wildlife officials air-drop carrots, sweet potatoes to help struggling wallabies

What does 'Medicare for All' actually look like?

What is moral grandstanding and are you guilty of it?