As it orbits Earth once a month, the moon is up during the day half the time, pale against the blue sky. You can see it this weekend, if you look.

Research involving a non-invasive scan of living human embryos shows that some muscles, thought to have been abandoned by our mammalian ancestors 250 million years ago, are still present before birth. They're among the oldest, albeit fleeting, remnants of evolution yet seen in humans.

Our global human population was estimated to reach 6 billion on today's date in 1999. Eleven years later, in 2011, Earth had gained another billion people. Today - October 12, 2019 - it stands at about 7.7 billion, according to United Nations estimates.

A new study suggests that about 4,000 years ago, a combination of isolation, extreme weather, and the arrival of humans on Wrangel Island in the Arctic Ocean killed off Earth's last population of mammoths.

The legacy of the Harvest and Hunter's Moons are the grand procession of moonlit nights in the season of waning daylight. In 2019, watch for the full, or nearly full moon, around October 11, 12, 13 and maybe even 14.

On average the ocean is 2.3 miles (3.7 km) deep, but many parts are much shallower or deeper. In the deepest zones, life forms have adapted to live in the dark, under crushing water pressure.

The Cassini mission to Saturn is over, but scientists still pore over its data. The newest discovery is of organic compounds - the ingredients of amino acids, the building blocks of life - in water vapor plumes from Saturn's moon Enceladus.

Scientists working with the Curiosity rover have found salt-enriched rock at a place called Sutton Island on Mars. The rocks suggest ponds with briny water on Mars, billions of years ago.

The stars are accessible to everyone, but where can you get the most from the night sky? Here are 10 great dark-sky places - mostly in the U.S. but also in Australia, New Zealand and Chile - for skywatching and stargazing.

Astronomers have found 20 new moons orbiting Saturn, bringing the planet's total number of moons to 82. That surpasses Jupiter, which has 79.