October birthstone: opal or tourmaline

Take your pick: the October birthstone is either the striking iridescent opal or the many-colored tourmaline. Learn the lore of these gemstones here.

Artificial intelligence’s racial and gender bias problem

Artificial intelligence sometimes discriminates by race and sex. Rights-based regulations are needed to ensure that AI will not exacerbate inequalities.

Fossil footprints are oldest found in Americas

Fossil footprints discovered in White Sands National Park, New Mexico, are the oldest known in the Americas. These footprints date back 23,000 years.

Satellites versus stars: Which will dominate the sky?

In the battle of satellites versus stars, the motion of constellations of satellites will draw the eye and drown out the quiet background stars.

How many stars can you see?

Have you ever wondered how many stars are visible on a given night? It all depends on how dark your sky is, what your age is, and other limiting factors.

Einstein’s most famous equation: E=mc2

Einstein's most famous equation describing the relationship of energy and mass, E=mc2, first appeared in a scientific journal on September 27, 1905.

Futuristic space concrete uses astronauts’ blood

Scientists in the U.K. have developed a kind of "space concrete" using dust and human blood that could be used for future human habitats on Mars or the moon.

Pablo Neruda, a poet who embraced cosmic beauty

Pablo Neruda was a famous Chilean poet who wrote: "Every day you play with the light of the universe." Neruda died on this date, September 23, in 1973.

Bible story of Sodom revisited. Was it a meteor strike?

The Bible story of Sodom and Gomorrah describes ancient cities destroyed for their wickedness. New research suggests a meteor impact instead.

La Palma volcano lava headed to sea

The La Palma volcano has forced thousands to evaculate. Its lava is flowing through streets, filling swimming pools, headed to the sea.