Enjoying EarthSky? Subscribe.

103,824 subscribers and counting ...


When can you see Earth’s shadow?

Night falls when the part of Earth you’re standing on enters Earth’s shadow. Click here to expand this image. Image via NASA

Just like you or me, Earth casts a shadow. Earth’s shadow extends millions of miles into space, in the direction opposite the sun. There are several good times to think about and be aware of Earth’s shadow.

What’s the birthstone for January?

Image Credit: USGS

Image Credit: USGS

January’s birthstone, the garnet, symbolizes a light heart, loyalty and enduring affections.

The name “garnet” is derived from the Latin “granatum” meaning “pomegranate” because the crystals resemble the red color and seed-like form of this fruit. Most people think of the garnet as a red gemstone, but in fact, it exists in all kinds of colors, such as black, many shades of red and green, or even colorless.

Why does the new year begin on January 1?

Photo credit: Daniel Moile

The date of New Year’s Day seems so fundamental that it’s almost as though nature ordained it. But New Year’s Day is a civil event. Its date is not precisely fixed by a seasonal marker.

Earth is closest to the sun for 2012 on January 5

Why are some foods considered lucky for New Year’s?

Black-eyed peas form the base of the New Year’s Day triumvirate – along with greens and cornbread – for many U.S. southerners. Recipe via foodnetwork.com.

I’ve already invited the kids for black-eyed peas, greens and cornbread on New Year’s Day. As a born-and-raised U.S. southerner, I wouldn’t dream of passing a New Year’s Day without eating at least a few black-eyed peas. This year, it occurred to me to wonder why this food – plus the greens and the cornbread – are considered lucky for New Year’s. I found out that this deep tradition of the U.S. South dates back to the Civil War.

What’s the birthstone for December?


Happy birthday to all our December friends! December has two birthstones, turquoise and zircon.

New record for the coldest place on Earth

NASA scientists have discovered the coldest place on our planet. It’s a high ridge in Antarctica on the East Antarctic Plateau. On a clear winter night, temperatures can dip below minus 133.6 degrees F (minus 92 degrees C)

The new record is several degrees colder than the previous low of minus 128.6 F (minus 89.2 C), set in 1983 at the Russian Vostok Research Station in East Antarctica.

Why aren’t the earliest sunsets on the shortest day?

In early December, the Southern Hemisphere is approaching its summer solstice.  Sunset in that hemisphere will continue coming later until early July.  Photo of sunset with crepuscular rays by Phil Rettke Photography in Ipswich QLD Australia.  Visit Phil Rettke on Facebook.

Photo of sunset with crepuscular rays by Phil Rettke Photography in Ipswich QLD Australia. Visit Phil Rettke on Facebook.

The winter solstice is the shortest day, but the earliest sunsets come a couple of weeks before the solstice. That’s true for both hemispheres. If you’re in the Northern Hemisphere your earliest sunsets will be in early to mid-December. If you’re in the Southern Hemisphere, your earliest sunrises are coming now.

Why do we scream?

Despite our fascination with screams, science knows relatively little about them.

Harold Gouzoules is one of the few scientists researching human screams. He collects them and analyzes their tone, pitch, and frequency to try and uncover the hidden patterns and complexities carried in one of the most intense human sounds.

What’s the birthstone for November?

Happy birthday to all you November babies! Your birthstone is the topaz.

The word “topaz” comes from a Sanskrit word meaning “fire.” And in ancient lore, the topaz could be used to control heat. It was said to have the power to cool boiling water, as well as excessive anger. As medication, topaz was used to cure fever.

Why does the moon look so big on the horizon? It’s called the moon illusion

We’ve all seen a full moon looming large shortly after it rises, when it’s still hugging the horizon. It’s not caused by any physical effect. Instead, it’s an illusion, a trick your brain is playing. Astronomers call it the moon illusion.