Billions of years ago, Mars was a much different place than it is today. Its atmosphere was thicker and warmer, liquid water flowed on its surface, and the planet was geologically active. Due to its lower gravity, this activity led to the largest volcanoes in the Solar System (Olympus Mons and the Thetis Mons region) and the longest, deepest canyon in the world (Valles Marineris). Unfortunately, Mars’ interior began to cool rapidly, its inner core solidified, and geological activity largely stopped. For some time, geologists have believed that Mars was essentially “dead” in the geological sense.
However, recent studies have provided seismic and geophysical evidence that Mars may still be “slightly alive.” In a recent study, scientists from the University of Arizona (ASU) challenged conventional views of Martian geodynamic evolution by discovering evidence of an active mantle plume pushing its way through the crust, causing earthquakes and volcanic eruptions. Combined with some serious marsquakes recorded by NASA’s InSight lander, these finding suggests that there is still some powerful volcanic action beneath the surface of Mars.
For decades, scientists have theorized that a massive impact caused the Cretaceous-Paleogene extinction event. This event occurred about 66 million years ago and caused the mass extinction of about 75% of all plant and animal species on Earth (including the non-avian dinosaurs). With the discovery of the massive Chicxulub crater in the Yucatan Peninsula (southern Mexico) in the 1970s, scientists concluded that they’d found the impact responsible. Based on all the available data, the Chicxulub Impact event is believed to have been as powerful as 100,000 billion metric tons (110,231 U.S tons) of TNT.
This blast was more powerful than all the nuclear devices in the world combined and sent an estimated 25 trillion metric tons (~27.5 US tons) of hot dust, ash, and steam into the atmosphere, creating a global winter. But according to new research led by the University of Michigan, an international team of geologists has determined that the impact also created a global tsunami. According to their findings, this tsunami was 30,000 times more powerful than the 2004 Indian Ocean tsunami, one of the largest and most devastating tsunamis on record.
Today, the Earth’s seven continents are distributed across the surface, with North and South America occupying one hemisphere, Africa, Europe, Asia, and Australia occupying the other, and Antarctica sitting alone around the South Pole. However, these continents were arranged in entirely different configurations throughout Earth’s history. On occasion, they formed supercontinents like Gondwana (ca. 550 to 180 million) and Pangaea (ca. 335 to 200 million years ago) that were surrounded by “superoceans.”
Eventually, the Earth’s tectonic plates will come together again to form the world’s next supercontinent. According to new research led by Curtin University in Bentley, Australia, this will happen roughly 200 to 300 million years from now. As they determined through a series of simulations, this will involve the Americas drifting westward until they collide with Australia and Asia (eliminating the Pacific Ocean) and Antarctica moving north to join them. This will give rise to the new supercontinent they have named “Amasia,” which will also have profound implications for life on Earth.
Ancient impacts played a powerful role in Earth’s complex history. On other Solar System bodies like the Moon or Mercury, the impact history is preserved on their surfaces because there’s nothing to erase it. But Earth’s geologic activity has erased the evidence of impact craters over time, with some help from erosion.
Earth’s complex history has elevated its status among its Solar System siblings and created a world that’s rippling with life. Ancient giant impacts have played a role in that history, bringing catastrophe and disruption and irrevocably changing the course of events. Deciphering the role these giant impacts played is difficult since the evidence is missing or severely degraded. So how do scientists approach this problem?
On Earth, shifts in our climate have caused glaciers to advance and recede throughout our geological history (known as glacial and inter-glacial periods). The movement of these glaciers has carved features on the surface, including U-shaped valleys, hanging valleys, and fjords. These features are missing on Mars, leading scientists to conclude that any glaciers on its surface in the distant past were stationary. However, new research by a team of U.S. and French planetary scientists suggests that Martian glaciers did move more slowly than those on Earth.
Early Earth was a wild and wooly place. In its first billion years, during a period called the Archean, our planet was still hot from its formation. Essentially, the surface was lava for millions of years. Asteroids bombarded the planet, and the place was still recovering from the impact that formed the Moon. Oceans were beginning to form as the surface solidified and water outgassed from the rock. The earliest atmosphere was actually rock vapor, followed quickly by the growth of a largely hot carbon dioxide and water vapor blanket. Earth was just starting land masses that later became continents. For decades, geologists have asked: what started continental formation?
More than half a billion years ago, Earth experienced an almost-complete collapse of its magnetic field. It began in the early Cambrian period. Then, after a period of about 15 million years, the field began to grow again. The cause of that collapse and the bounceback of the field was a mystery. Then, a group of geologists studied rocks from Oklahoma that were created during that time. Magnetic markers in the rocks’ minerals pointed toward an event that began some 550 million years ago. That was before the introduction of multicellular life on our planet.
If we think untangling Earth’s complex geological history is difficult, think of the challenge involved in doing the same for Mars. At such a great distance, we rely on a few orbiters, a handful of rovers and landers, and our powerful telescopes to gather evidence. But unlike Earth, Mars is, for the most part, geologically inactive. Much of the evidence for Mars’ long history is still visible on the surface.
That helped scientists identify the source of one of our most well-known meteorites.
With the development of modern telescopes and robotic explorers, scientists have learned a great deal more about these polar deposits. In 2011, they learned that unlike the northermost ice sheet, the southern cap is largely composed of frozen carbon dioxide (aka. “dry ice”). According to new research led by the Planetary Science Institute (PSI), glaciers of carbon dioxide ice have been moving and carving features in the southern polar region for more than 600,000 years – and are on the move right now!
Within Jupiter’s massive system of satellites, four large moons really stand out. They’re known as the “Galilean Moons” in honor of Galileo Galilee, who made the first recorded observations of them in 1610. The innermost of these moons is the rocky moon Io, which is slightly larger than Earth’s Moon and slightly denser. With more than 400 active volcanoes on its surface, it is the most geologically active body in the Solar System.
Add to that the intense radiation it gets from Jupiter’s magnetic field, and it’s arguably one of the most hellish environments in the Solar System! Nevertheless, scientists have long been puzzled by the meandering ridges visible on the surface, which are as large as any seen here on Earth. Thanks to a recent study led by Rutgers University, there’s now an explanation for how these formations can exist on a surface as icy and volcanic as Io’s.