A new study analyzed Martian glaciers to discover that the planet had numerous ice ages.
Geologists unraveled the mysteries of Martian glaciers, concluding that the planet had up to 20 separate ice ages. The groundbreaking new analysis promises to substantially boost our understanding of the Red Planet.
Mars is covered in glaciers, frozen upon the surface of the Red Planet for over hundreds of millions years. Geologists have debated whether the glaciers were all a result of one long Ice Age or caused by individual ice ages over a long span of time. As ice ages are caused by the changing tilt of a planet's axis (also known as obliquity), the results promise to show scientists the variations in the Martian orbit and climate. Pinpointing the timeline of the ice ages can also help scientists understand what kinds of things may be trapped under the ice, including rocks, fossils, microbes, and gases.
The study was led by geology professor Joe Levy of Colgate University. The team also involved scientists from NASA, the University of Arizona, Fitchburg State University, and the University of Texas–Austin.
"There are really good models for Mars' orbital parameters for the last 20 million years," said Levy in a press release. "After that the models tend to get chaotic."
Levy's team looked at 45 glaciers using high-resolution images from the Mars Reconnaissance Orbiter satellite. It's able to achieve resolution of 25 cm per pixel, which is good enough to "see things the size of a dinner table," explained Levy.
Boulders were found grouped in distinct bands on the surfaces of the Martian glaciers, suggesting multiple ice ages over hundreds of millions of years.
Credit: Levy et al./ PNAS/ Colgate University.
The professor used both artificial intelligence and 10 university students, who over two summers analyzed about 60,000 rocks. They focused on the distribution, clustering, and the sizes of the rocks, looking for signs of erosion. The team's so-called "virtual field work" allowed the scientists to map the boulders across Martian glaciers.
The scientists saw that to their surprise, the rocks moved along the inside of the glaciers, rather than eroding in predicted fashion. The rocks also seemed grouped across the glaciers, suggesting separate flows that took place over time, rather than being caused by one major event.
Using the data, the researchers found that Mars went through from six to 20 distinct ice ages over 300 to 800 million years.
"These glaciers are little time capsules, capturing snapshots of what was blowing around in the Martian atmosphere," shared Levy. "Now we know that we have access to hundreds of millions of years of Martian history without having to drill down deep through the crust — we can just take a hike along the surface."
Levy's team is currently mapping new Martian glaciers, looking to reveal more of the planetary history of Mars.
Check out the paper for yourself, published in PNAS (Proceedings of the National Academy of Sciences).
A new study discovers why whales grew to be the largest animals on our planet.
While we tend to think of dinosaurs as gigantic, they are not the biggest animals ever. In fact, the largest animal to have ever lived is around on our planet right now. It's a blue whale, a giant that can reach up to 100 feet (30m) in length and 200 tons (400,000 pounds) in weight. This huge beast, while endangered, is still roaming our waters, with an estimated 10,000 to 25,000 blue whales alive today. Now scientists figured out why baleen whales like the blue whale got to be so big.
One previous theory explaining the gigantism of whales saw their large size as an adaptation necessary to fight off megasharks and other enormous prehistoric animals. But scientists found out that until about 4.5 million years ago whales stayed moderate in size - about 10 meters long. Then, near the beginning of the first Ice Age, they started growing larger.
What happened? Researchers from the University of Chicago, Stanford University and the Smithsonian's National Museum of Natural History studied fossils of 63 extinct whales to figure it out. They propose that the explanation lies in the dramatically changed diets of the animals.
"We might imagine that whales just gradually got bigger over time, as if by chance, and perhaps that could explain how these whales became so massive," said the study's co-author Graham Slater, who teaches geophysical sciences at the University of Chicago. "But our analyses show that this idea doesn't hold up—the only way that you can explain baleen whales becoming the giants they are today is if something changed in the recent past that created an incentive to be a giant and made it disadvantageous to be small."
As glaciers grew during the Ice Age, their “runoff" or melting periods in the spring and summer dumped nutrients into the ocean, allowing for an explosion in the amount of tiny crustaceans called krill and other small animals whale eat. Before this, food for the whales was available all throughout the year, but the resulting climate change caused much of that supply to disappear.
Instead, food was now available in abundance seasonally and only in certain areas. This encouraged the whales to grow bigger and faster, to be able to find, consume and store food more efficiently. The reason the bigger whales were preferred by evolution is that they could survive the long migrations necessary to get to the next patch of food.
Check out this video from Science Magazine:
The research not only sheds light on the mystery of the whales' size but also provides insight into how oceans sustain life.
"An animal's size determines so much about its ecological role," said Smithsonian's Nicholas Pyenson, the study's co-author. "Our research sheds light on why today's oceans and climate can support Earth's most massive vertebrates. But today's oceans and climate are changing at geological scales in the course of human lifetimes. With these rapid changes, does the ocean have the capacity to sustain several billion people and the world's largest whales? The clues to answer this question lie in our ability to learn from Earth's deep past—the crucible of our present world—embedded in the fossil record."
You can read the study in the Proceedings of the Royal Society B.