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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.

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.

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.

Animal shapes in clouds, and other pareidolia

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?