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Category: asteroid/comet impacts

How worried should you be about an asteroid smashing into Earth?

Somewhere, out in the cold depths of space, there is a space rock that could destroy a large chunk of life on Earth. Is this fate inevitable? Could we find a way to stop it, or will we eventually suffer the same fate as the dinosaurs? And should this existential threat be keeping you up at night? Here’s what we know.

The asteroid that killed the dinosaurs 66 million years ago was at least 10 kilometres across, big enough to cause megatsunamis, ignite enormous forest fires and darken the skies the world over. Asteroids of that size are estimated to hit Earth about every 60 million years, based on the planet’s crater record. For the next size class down, asteroids about 1 kilometre across, estimates suggest they hit Earth about every million years, and the most recent one was about 900,000 years ago. Those numbers are enough to make you nervous.

But one of the things that sets humanity apart from the dinosaurs is our ability to look out into space and interpret what we see there. Naturally, researchers around the world have used this ability to attempt to learn how many asteroids are out there and what proportion of them are on trajectories that could be dangerous.

Image: angel_nt/Getty Images.

The dinosaurs were wiped out by an asteroid, but does that mean we risk suffering the same fate — and should you be worried about the possibility? Leah Crane sets the matter straight.

By Leah Crane

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From deer to chickadees: How fewer social encounters could raise extinction risk

Imagine an asteroid striking Earth and wiping out most of the human population. Even if some lucky people survived the impact, Homo sapiens might still face extinction, because the social networks humans rely on would collapse.

This dynamic also plays out in the wild.

Social interactions are essential for many animals, helping them to locate food, spot predators and raise offspring. Without such connections, individuals can struggle to survive.

Evidence of ‘lightning-fast’ evolution found after Chicxulub impact

The asteroid that struck the Earth 66 million years ago devastated life across the planet, wiping out the dinosaurs and other organisms in a hail of fire and catastrophic climate change. But new research shows that it also set the stage for life to rebound astonishingly quickly.

New species of plankton appeared fewer than 2,000 years after the world-altering event, according to research led by scientists at The University of Texas at Austin and published in Geology.

Lead author Chris Lowery, a research associate professor at the University of Texas Institute for Geophysics (UTIG) at the Jackson School of Geosciences, said that it’s a remarkably quick evolutionary feat that has never been seen before in the fossil record. Typically, new species appear on roughly million-year time frames.

NASA supercomputer just predicted Earth’s hard limit for life

Scientists have used a NASA-grade supercomputer to push our planet to its limits, virtually fast‑forwarding the clock until complex organisms can no longer survive. The result is a hard upper bound on how long Earth can sustain breathable air and liquid oceans, and it is far less about sudden catastrophe than a slow suffocation driven by the Sun itself. The work turns a hazy, far‑future question into a specific timeline for the end of life as we know it.

Instead of fireballs or rogue asteroids, the simulations point to a world that quietly runs out of oxygen, with only hardy microbes clinging on before even they disappear. It is a stark reminder that Earth’s habitability is not permanent, yet it also stretches over such vast spans of time that our immediate crises still depend on choices made this century, not on the Sun’s distant evolution.

The new modeling effort starts from a simple premise: if I know how the Sun brightens over time and how Earth’s atmosphere responds, I can calculate when conditions for complex life finally fail. Researchers fed a high‑performance system with detailed physics of the atmosphere, oceans and carbon cycle, then let it run through hundreds of thousands of scenarios until the planet’s chemistry tipped past a critical point. One study describes a supercomputer simulation that projects life on Earth ending in roughly 1 billion years, once rising solar heat strips away most atmospheric oxygen.

Supernova immersion model suggests Earth-like planets are more common in the universe

Rocky planets like our Earth may be far more common than previously thought, according to new research published in the journal Science Advances. It suggests that when our solar system formed, a nearby supernova (the massive explosion of a star near the end of its life) bathed it in cosmic rays containing the radioactive ingredients to make rocky, dry worlds. This mechanism could be ubiquitous across the galaxy.

Earth-like planets are thought to form from planetesimals (objects made of rock and ice) that were dried out early in the solar system’s history. This process required a lot of heat, which came primarily from the radioactive decay of short-lived radionuclides (SLRs), such as aluminum-26. Previous analysis of meteorites, which are ancient records of the early solar system, confirmed the abundance of SLRs at this time.

Flaws in previous models However, models that explain supernovae as the sole source of these SLRs cannot accurately match the quantity of the nucleotides found in meteorites. To deliver enough radioactive material, the supernova would have to be so close to the early solar system that it would have destroyed the disk of dust and gas where the planets were forming.

Hubble captures rare collision in nearby planetary system

In an unprecedented celestial event, NASA’s Hubble Space Telescope (HST) captured the dramatic aftermath of colliding space rocks within a nearby planetary system.

When astronomers initially spotted a bright object in the sky, they assumed it was a dust-covered exoplanet, reflecting starlight. But when the “exoplanet” disappeared and a new bright object appeared, the international team of astrophysicists—including Northwestern University’s Jason Wang—realized these were not planets at all. Instead, they were the illuminated remains of a cosmic fender bender.

Two distinct, violent collisions generated two luminous clouds of debris in the same planetary system. The discovery offers a unique real-time glimpse into the mechanisms of planet formation and the composition of materials that coalesce to form new worlds.

A volcano or a meteorite? New evidence sheds light on puzzling discovery in Greenland’s ice sheet

Buried deep in Greenland’s ice sheet lies a puzzling chemical signature that has sparked intense scientific debate. A sharp spike in platinum concentrations, discovered in an ice core (a cylinder of ice drilled out of ice sheets and glaciers) and dated to around 12,800 years ago, has provided support for a hypothesis that Earth was struck by an exotic meteorite or comet at that time.

Our new research published in PLOS One offers a much more mundane explanation: this mystery signature may have originated from a volcanic fissure eruption in Iceland, not space.

The timing matters. The platinum spike occurs near the beginning of our planet’s last great cold period, the Younger Dryas Event. This lasted from about 12,870 to 11,700 years ago and saw temperatures plummet across the northern hemisphere.

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