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?
Collapsing ice shelves on the eastern coast of Antarctica has revealed something never seen before: a landform that might be an island. But this is not the first newly revealed island off the Antarctic coast. A series of islands have appeared as the ice shelves along the continent’s coastline has disintegrated over the past few years.
The two largest reservoirs in the United States are now at their lowest levels since they were first created. After several decades of drought – with the past two years classified as intense drought in the US Southwest — both Lake Powell and Lake Mead are shrinking. Recent satellite images show just how dramatic the changes have been, due to the ongoing the climate crisis..
Science fiction author Frank Herbert is renowned for the richly-detailed worlds he created. None of his work is more well-known than “Dune,” which took him six years to complete. Like his other work, Dune is full of detail, including the description of planet Dune, or as the Fremen call it, Arrakis.
Dune is an unforgiving desert world that suffers powerful dust storms and has no rainfall. Scientists who specialize in modelling climates set out to see how realistic Dune is compared to exoplanets. Their conclusion?
Frank Herbert did a great job, considering he created Dune in the 1960s.
Mars is an arid place, and aside from a tiny amount of water vapour in the atmosphere, all water exists as ice. But it wasn’t always this arid. Evidence of the planet’s past wet chapter dots the surface. Paleolakes like Jezero Crater, soon to be explored by NASA’s Perseverance Rover, provide stark evidence of Mars’ ancient past. But what happened to all that water?
It disappeared into space, of course. But when? And how quickly?
Every 200,000 to 300,000 years Earth’s magnetic poles reverse. What was once the north pole becomes the south, and vice versa. It’s a time of invisible upheaval.
The last reversal was unusual because it was so long ago. For some reason, the poles have remained oriented the way they are now for about three-quarters of a million years. A new study has revealed some of the detail of that reversal.
We can thank NASA’s New Horizons spacecraft for opening our eyes up to Pluto’s complexity. On July 14th, 2015, the spacecraft came within 12,500 km (7,800 mi) of the dwarf planet. During the flyby, New Horizons was able to characterize Pluto’s atmosphere and its surface.
Among the things New Horizons saw was a region of snowcapped mountains.
Comets visit the inner Solar System, and leave without saying goodbye. Maybe they leave a trail of dust behind, and when the Earth passes through it, we get a pretty light show in the night sky, in the form of a meteor shower. Likewise, asteroids frequently go whizzing by, though they don’t leave us with a pyrotechnic display.
Sometimes these rocky interlopers head straight for Earth. And when they do, the results can be cataclysmic, like when an asteroid struck Earth about 66 million years ago, wiping out the dinosaurs and 75% of life on Earth. Other times, it’s not quite as cataclysmic, but still devastating, like in about 2350 BC, when debris from a disintegrating comet may have caused the collapse of an ancient empire.
But regardless of the severity of any of these individual events, the conclusion is crystal clear: Earth’s history is intertwined with the coming and going of space rocks. The evidence is all around us, sort of.
There are a handful of major science institutions around the world that keep track of the Earth’s temperature. They all clearly show that the world’s temperature has risen in the past few decades. One of those institutions is NASA.