Shark Planet

Healing the Ozone Hole

Ozone makes up a tiny portion of Earth’s atmosphere, but it allows for life on Earth. The oxygen we breathe is what’s called molecular oxygen, O2—two atoms of oxygen bonded together. High above Earth’s surface, in the stratosphere, the Sun’s intense radiation splits those oxygen molecules, and a tiny fraction reform as ozone, or O3—three oxygen atoms, with a very important property. Ozone absorbs UV-C, a form of ultraviolet light so dangerous, it can destroy microbes and alter DNA in larger lifeforms. If Earth weren’t protected by its ozone layer, scientists think UV-C would sterilize its surface, perhaps wiping out surface life. But ozone is vulnerable. In the 1930s, aiming to replace more dangerous refrigerants, scientists developed chlorofluorocarbons, or CFCs. They proliferated in cooling systems around the world. But the chlorine in CFCs, when it entered the atmosphere, bonded with free oxygen and disrupted ozone formation. Deeply worried about UV-C damage, scientists convinced politicians of the threat, and in 1987, the Montreal Protocol was signed by every nation on Earth. Since then, countries have phased out CFCs, and the ozone layer is rebounding. It should return to pre-CFC levels in 30 years. A positive example of how humans can unite to solve environmental problems.

Solar Flares vs Coronal Mass Ejections

Solar flares and coronal mass ejections are the most powerful explosions in our solar system—too large, heavy and fast-moving to imagine. But they’re not the same thing. They occur mostly when the Sun’s magnetic poles prepare to flip, every 11 years or so, in an event called a “solar maximum.” Magnetic fields deep within the Sun punch up to create two very different anomalies on the surface: Solar flares are enormous flashes of broad-spectrum electromagnetic radiation, from radio waves to gamma waves, released with the force of billions of hydrogen bombs. They stay largely within the Sun’s atmosphere, but when their energy does reach Earth, traveling at nearly 700 million miles an hour, it can degrade radio communications and black out navigation. Coronal mass ejections are made up of matter, not radiation, and instead can contain a billion tons of superheated solar plasma. Some collapse back into the Sun, but others leave the Sun’s atmosphere and enter space. There they could expand to a million miles wide. Traveling at speeds of only a few million miles an hour, they can reach Earth in around 15 hours … where they can cause amazing auroras—northern and southern lights—as well as interfere with power grids, as we’ve discussed on prior episodes. Fortunately, NASA has built a satellite early warning system so we can prepare our critical infrastructure for this powerful solar weather.

Dino Diseases

Dinosaurs, like most large animals today, had long lives. Therapods like T. rex lived to about 30 years, while giant sauropods could live to 60. And over those long lifespans, like all of us, they got sick. Soft tissues don’t fossilize as well as bone, but scientists have documented diseases, from the mundane to the mortal, in all types of dinosaurs. Feathered dinosaurs had dandruff. Others showed, through preserved skin fragments, dermatitis or sores from healing wounds.; Some dino joints exhibited inflammation and malformation, likely the product of years of achy arthritis. Others contained uric acid crystals similar to gout today. A Diplodocus showed evidence of an upper respiratory infection that could have spanned its entire long neck—that’s a lot of sniffles! Others showed illnesses in their jaws and throats similar to those in modern raptors. Paleontologists have found telltale signs of bone infection causing changes in bone growth, size and density. And aggressive bone cancers that could have spread to other parts of the body. They even suspect that dinosaurs had an early version of malaria, transmitted by a now-extinct insect. Most dino diseases have gone extinct, too, though many are still around. But don’t worry about catching them. Since crocodiles and birds are more closely related to dinosaurs, they’re the ones who are more susceptible.

The Changing Tides

It may appear that tides come in and out. But that’s not really what happens. In fact, the Moon pulls the ocean toward it, creating what’s called a “tidal bulge” of higher water surface. The tidal bulge happens on the side of Earth facing the Moon, with a balancing but slightly lower bulge on the other side of Earth. As Earth rotates, land masses come into contact with these higher water levels and the tide appears to “come in.” When land rotates past the tidal bulge, the tide “goes out.” The Sun also pulls on Earth’s oceans, but since it’s so much farther away, its gravitational pull is weaker than the Moon’s. However, twice a month, the Sun, the Moon and the Earth line up, amplifying the gravitational pull on oceans, causing the highest “spring” tides. A week later, the Sun is perpendicular to the Moon, pulling the oceans slightly toward it and reducing the tidal bulge, producing the lowest “neap” tides. The distances of Earth and Moon from the Sun vary through time, impacting gravitational forces that influence tide heights. And that’s not all. The shape and slope of the shoreline can also affect tides. Long, narrow inlets experience much more dramatic tidal changes than wide, flat shorelines. And high winds from storms can also push high tides further inland than normal. The Moon remains by far the strongest driver of tides, but the Sun, geography and weather also play a role.

Opposable Thumbs Up!

Many evolutionary advances, like big brains, have given humans an advantage over other animals. Perhaps one of the least appreciated is the thumb. Specifically, the opposable thumb--meaning opposite our fingers--with the ability to touch each finger across the palm, enabling our hands to manipulate small objects. Around 400,000 years ago, Neanderthals had opposable thumbs, but they were much less dexterous than those of modern humans, who evolved later, around 300,000 years ago. Our stronger, longer, more nimble thumbs allowed us the fine motor skills to more easily make and maneuver stone tools, which in turn allowed us to more effectively butcher animals and process grains and other food sources to broaden our diet. They also helped build our textile culture, spinning fiber into yarn, to sew using needles or weave into fabric, to make clothes to protect ourselves from the elements. They helped us communicate and create art that built stronger social connections. To pick berries, use fishhooks, and tend livestock. In short, our opposable thumbs may have made early human technology and sophisticated cultural practices possible. This helped humans to outcompete Neanderthals, and other large predators, and survive difficult conditions—to make it into the modern world. We take them for granted, but next time you look at your hands, give your two thumbs … two thumbs up.