A Canadian lake defines the moment humans changed the planet forever

By Katie Hunt, CNN

(CNN) — Rocks, cliffs, muddy sediment. These natural features may not be that exciting to look at for some of us, but for geologists they bristle with meaning.

The story they tell is our planet’s history, chronicling how continents, mountain ranges and oceans formed and glaciers spread and receded. Fossils embedded in rock reveal intriguing details about animals, plants and other life-forms that once called Earth home.

If humans went extinct, what trace would we leave in the geological record? An announcement this week suggests that humanity has already made an indelible impact and one that warrants a new chapter in Earth’s history.

Consequences

Scientists say they’ve identified a site that marks the birthplace of the Anthropocene — a new geological epoch that captures how profoundly humans have altered the world.

The Anthropocene Working Group determined in 2016 that the epoch began around 1950 — the start of the era of nuclear testing.

The international research group says that Crawford Lake in Ontario best charts humanity’s impact on Earth. Sediment cored from the lake bed showed geochemical traces of nuclear bomb tests, specifically radioactive plutonium.

However, not everyone agrees the Anthropocene is a geological reality — or that researchers have enough evidence to formally declare it a new epoch.

Solar update

Over the course of an 11-year solar cycle, the sun transitions from a calm period to one that is very intense and active. Cool, dark sunspots on the sun’s surface increase in number, causing solar flares and mass ejections of plasma.

The peak of the current solar cycle was forecast to take place in July 2025. However, our star is growing increasingly active. Scientists now think the solar maximum, or the peak of solar activity, is more likely to occur in mid-to-late 2024.

What does that mean for us on Earth? On the upside, it means that the auroras that dance around Earth’s poles will be visible in more places.

However, more intense solar storms can affect electric power grids, GPS and aviation, and satellites in low-Earth orbit. These events also cause radio blackouts and can even pose risks for crewed space missions.

A long time ago

Ancient Egyptians used highly formalized workflows to execute their paintings. But these exacting artists didn’t always get everything right the first time.

A cutting-edge technique is uncovering hidden details about paintings in two tombs that date back more than 3,000 years. Egyptologist Philippe Martinez of Sorbonne University said one of the tombs was “a little bit like the Mona Lisa of Egypt.”

The discoveries were made by using portable chemical imaging technology, which allows researchers to analyze the artwork while inside the tomb rather than waiting to look at it inside a museum or lab.

Other worlds

The NASA Mariner 4 mission captured the first photos of another planet taken from space in 1965. The spacecraft flew 6,118 miles (9,846 kilometers) above the surface of Mars, but the first image made public wasn’t quite what the space agency intended.

Back then, it took 10 hours to relay a single image to Earth — incredibly slow by today’s standards. As anxiety built during the wait, some members of the Mariner 4 team took matters into their own hands and assembled a “color by numbers” image based on representations of data to make sure the equipment was working properly.

Despite the best efforts of NASA Jet Propulsion Laboratory’s communications team, the press glimpsed the hand-colored image, and the artwork became the first close-up shot of Mars from space to be seen on TV.

The actual photo was released the next day. In total, Mariner 4 took 22 ground-breaking images, and they revealed craters on the Martian surface, which surprised scientists.

Dig this

Humans not only lived in South America at the same time as giant sloths — they also handcrafted pendants from bony material in the ice age creature’s skin, according to a new study.

The maker or makers of the recently discovered three artifacts perforated a hole in the sloth bone and polished them, according to an analysis of microscopic marks. The species of giant sloth the bones belonged to would have weighed more than 1,300 pounds (about 600 kilograms), bigger than most current-day brown bears.

The discovery is exciting on two fronts: It puts humans in the Americas several thousand years earlier than many archaeologists thought, and the three pendants are the oldest known personal adornments unearthed on the landmass.

Explorations

Check out these three captivating stories.

— The Webb space telescope has been observing the universe for one year, and a stunning new image marks the milestone.

— The climate crisis is altering the color of the world’s oceans, although the change isn’t yet visible to the naked eye.

— A scorching hot planet that zips around its host star every 19 hours is the shiniest exoplanet ever discovered.

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