Why a day is 24 hours long, and why it used to be 20 hours

Learn why on Earth a day is 24 hours long, how it used to be closer to 20 hours long, and how a warming atmosphere might extend the length of a day.

Satellite views lightning from space to help predict storms

The European Space Agency has a new satellite that is capturing views of lightning from space. The satellite will help improve forecasts and make air travel safer.

99% of the world’s population in sunlight July 8 … and other dates

Fact-checkers at timeanddate.com discovered 99% of the world's population experiences some sunlight at 11:15 UTC on July 8 ... along with many other dates!

Circumhorizon arc or iridescent cloud?

It's easy to confuse a circumhorizon arc with an iridescent cloud, and vice versa. Circumhorizon arcs are more commonly seen at this time of year.

What is a derecho? A destructive, bow-shaped storm

A derecho tore across the Midwest on June 29, 2023. These dangerous storms pack strong winds and race over large areas of land. Learn more about derechos here.

What is a heat dome? Southern U.S. feeling its effects

What is a heat dome and how does it affect those who are living under one? Learn more about this meteorological phenomenon here.

Canadian smoke crosses the Atlantic and reaches Europe

Canadian smoke from raging wildfires has now crossed the Atlantic to darken skies over Europe. The smoke over Europe is high in the atmosphere.

What is airglow? This glowing light is not an aurora

Airglow is a light that occurs high in Earth's atmosphere. It's usually too dim to see with the eye, but photographers can capture glorious photographs of it.

Hummingbirds, tiny and colorful: Lifeform of the week

Hummingbirds are tiny, fast and colorful. See some gorgeous photos of these birds and learn more about this fantastic lifeform of the week here.

Sea-going search for alien fragments yields odd spherules

Avi Loeb and a team of scientists are combing the ocean floor near Papua New Guinea for alien fragments. They've found some odd tiny metallic spherules.