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Autumn 2016 in the Colorado Rocky Mountains. Photo via Jessi Leigh Photography.  Thanks Jessi!

Why do leaves change color in fall?

In the fall, the leaves of some trees turn yellow, orange or red. The bright colors are wonderful to behold. But do they have some hidden purpose?


Are we in a sixth mass extinction?

This short video puts modern extinctions in context by comparing them with Earth’s 5 previous mass extinctions.

Great white shark and bluefin tuna, at Monterey Bay Aquarium. Courtesy of Niall Kennedy via Flickr.com

Shark and tuna convergent evolution

Lamnid sharks and tuna have similar physical traits that make them top ocean predators. But, a new study says, they took very different evolutionary paths.

A polar bear tests the strength of thin sea ice. Image via Mario Hoppmann/imaggeo.egu.eu

Melting sea ice leaves polar bears hungry

“Sea ice really is their platform for life. They are capable of existing on land for part of the year, but the sea ice is where they obtain their main prey.”


A Chinese perspective on autumn

Autumn is connected in Chinese thought with the direction west, considered to be the direction of dreams and visions.

Image via NASA

Satellite sees 3 California wildfires

There were more than a dozen wildfires burning in California, as of September 20.

Photo via Manish Mamtani Photography

Why Earth has 4 seasons

Some assume our planet’s changing distance from the sun causes the change in the seasons. That’s logical, but not the case, for Earth.

2016's summertime Arctic sea ice minimum, in contrast to the average. Image via NASA/NSIDC.

Arctic sea ice 2nd-lowest on record

Summertime sea ice in the Arctic reached a minimum on September 10 (unless it goes lower still). It’s now tied for the second-lowest minimum in the satellite era.

January 1, 2015 sunset by Helio de Carvalho Vital.  Shot 3 of 6.

Day and night exactly equal at equinoxes?

On the day of the equinox, the center of the sun would set about 12 hours after rising – given a level horizon, as at sea, and no atmospheric refraction.

Composite image of the crack in Larsen C ice shelf in Antarctica, acquired on August 22, 2016 by NASA's Terra satellite. Image via NASA Earth Observatory.

Crack advances across Antarctic ice shelf

Satellite images of the crack in Antarctica’s Larsen C ice shelf. If it breaks off, it’ll make an ice island in the Southern Ocean as large as one of the smallest U.S. states.

Ed Bettina Berg in Las Vegas, Nevada contributed this image of the 2016 Harvest Moon.

Shine on, Harvest Moon!

Photos of 2016’s beautiful Harvest Moon from the EarthSky community.

The feeling isn’t mutual. Image via caruba/Flickr

Lifeform of the week: Rats

The secret life of urban rats.

Image via NASA.

Probably no La Niña in late 2016

An extremely strong El Niño was in progress earlier this year. Historically, some are followed by a La Niña, but ocean temps suggest … not this year.

Image via bikeroar

August 2016 ties July for hottest month

The record-warm August continues a streak of 11 consecutive months that have set new monthly high-temperature records.


What if all of Earth’s ice melted?

What would Earth be like if all of its ice melted? New short video from the guys at AsapSCIENCE, featuring Bill Nye.

European earthworm species Lumbricus terrestris. Image courtesy of Simone Cesarz.

Earthworm invaders alter northern forests

Native plant diversity in forests of northern North America is declining due to an invasion by earthworms introduced hundreds of years ago from Europe.

A Livingston Parish deputy sheriff surveys flood damage from a boat on August 15, 2016.  Image courtesy of Rapides County Sheriff's Office

Climate change’s role in Louisiana floods

After a rapid assessment, scientists have concluded that climate change increased chances of the August record rains in Louisiana by at least 40%.

Adonis, a Bosnian pine, more than 1,075 years old, living in the alpine forests of the Pindos mountains in northern Greece. Image via Dr. Oliver Konter, Mainz

This is Europe’s oldest living tree

The scientists who discovered it in the highlands of northern Greece named it Adonis, for the Greek god of beauty and desire. It’s more than 1,000 years old.

Image Credit: Don DeBold

Lifeform of the week: Skunks

Evolutionary biology can explain skunks’ striking appearance, but only chemistry can get rid of the smell.

Humpback whale, via NOAA

A comeback for humpback whales

The international moratorium on whale-hunting is still in place, but – good news – some whales are coming off the U.S. endangered species list.