Enjoying EarthSky? Subscribe.

248,158 subscribers and counting ...

A Chinese perspective on spring

In Chinese thought, spring is associated with the direction east, the sunrise direction as Earth spins us toward the beginning of each new day.

When is the next leap year?

If there were no leap years, eventually February would be a summer month for the Northern Hemisphere. 2017 isn’t a leap year, but 2020 will be.

How many eclipses in 1 calendar year?

Every calendar year has at least 4, but 5, 6 or even 7 eclipses are also possible. Why don’t we see them all?

What is retrograde motion?

Retrograde motion of Jupiter or Mars or Saturn in our sky is an illusion, caused by Earth’s passing these slower-moving outer worlds. But there’s a real retrograde motion, too.

Today in science: Quasar mystery solved

In 1963, Maarten Schmidt suddenly realized that quasars are exceedingly distant and unimaginably luminous. His revelation changed our notion of what the universe is like.

Chinese New Year this weekend

The 2017 Chinese New Year – which coincides with the January new moon – starts this weekend and rings in the Year of the Rooster.

2017 has 2 Friday the 13ths

When a common year of 365 days starts on a Sunday, as it does this year, 2 Friday the 13ths are inevitable. The 1st one is in January.

No double moon in 2017, or ever

Can Mars ever appear as large as the moon in Earth’s sky? Heck no.

Leap second to be added December 31

Delay those New Year’s plans. World timekeepers will add a leap second just before midnight on December 31, 2016.

Solstice tale of two cities

December solstice sunrise comes at the same time for St. Augustine, Florida and New York City. But St. Augustine has an hour more of daylight than New York. Here’s why.

Geminid meteor shower 2016 ahead

Peak night for the Geminids in 2016 is December 13 (morning of December 14). Best around 2 a.m. Moonlight interferes but these meteors are bright. Maybe you’ll catch a cool photo!

A front view of Lucy, based on a reconstruction by paleoartist John Gurche. Image credit: Smithsonian Institution Human Origins Initiative. http://humanorigins.si.edu/australopithecus-afarensis-lucy-adult-female-reconstruction-base-al-288-1-artist-john-gurche-front

Human ancestor Lucy a tree climber

Lucy lived 3.18 million years ago in what’s now Ethiopia. An analysis of high-resolution CT scans of her fossilized skeleton shows she was equipped for climbing trees.

Last quarter moon 3rd of 4 this season

Usually there are only 3 last quarter moons in a season. The November 21, 2016 last quarter moon, though, counts as the 3rd of four.

Today in science: An island is born

On November 14 1963, crew aboard a trawler sailing near Iceland spotted a column of smoke rising from the sea surface. A new island, Surtsey, was being born.

Seeing things that aren’t there

Seeing animals in clouds, or a face in the moon, are examples of pareidolia. Look here for photos to test your own ability to see things that aren’t there.

Mount Hekla was called Gateway to Hell

Mount Hekla is Iceland’s 3rd most active volcano. A large eruption in 1104 earned it the moniker Gateway to Hell. Is Mount Hekla overdue for another eruption?

Can you see lights of Diwali from space?

The Hindu festival of Diwali was October 30, 2016. It’s a festival of light! But can you see the light of Diwali from space?

2016’s longest lunar month starts October 30

Lunar months vary in part because the moon’s orbit around Earth isn’t a perfect circle. Longest (and shortest) lunar months in 2016, here.

The general flow of global ocean circulation, with warm surface currents in red, and cold deep ocean currents in blue.Warm salty surface water from the Caribbean moves to the northern Atlantic Ocean, releasing heat to the atmosphere in those far nothern latitudes, then sinks to continue its journey as a cold south-moving current. Image via USGS.

Warm ocean currents are slowing down

Satellite data and ocean sensors show a definite slowdown since 2004 in ocean currents that warm eastern North America and western Europe.

Canela (left) and Blanquita (right) don’t need symbols to express their opinions. Image credit: Dominique Brand.

How to ask a horse what it wants

Do you want a blanket? Norwegian researchers recently described how they trained horses to use symbols to answer that question.