Space and astronomy news
Does life appear independently on different planets in the galaxy? Or does it spread from world to world? Or does it do both?
New research shows how life could spread via a basic, simple pathway: cosmic dust.
Continue reading “Cosmic Dust Could Spread Life from World to World Across the Galaxy”
It’s almost impossible to comprehend a supernova explosion’s violent, destructive power. An exploding supernova can outshine its host galaxy for a few weeks or even months. That seems almost impossible when considering that a galaxy can contain hundreds of billions of stars. Any planet too close to a supernova would be completely sterilized by all the energy released, its atmosphere would be stripped away, and it may even be shredded into pieces.
But like many things in nature, it all comes down to dose.
A certain amount of supernova activity might be necessary for life to exist.
Continue reading “Nearby Supernovae Were Essential to Life on Earth”
Earth has had a long and complex history since its formation roughly 4.5 billion years ago. Initially, it was a molten ball, but eventually, it cooled and became differentiated. The Moon formed from a collision between Earth and a protoplanet named Theia (probably), the oceans formed, and at some point in time, about 4 billion years ago, simple life appeared.
Those are the broad strokes, and scientists have worked hard to fill in a detailed timeline of Earth’s history. But there are a host of significant and poorly-understood periods in the timeline, lined up like targets for the scientific method. One of them concerns UV radiation and its effects on early life.
A new study probes the effects of UV radiation on Earth’s early life-forms and how it might have shaped our world.
Continue reading “The Early Earth was Really Horrible for Life”
Sometime around 2.4 billion years ago, a nascent planet Earth underwent one of the most dramatic changes in its history. Known as the Great Oxidation Event, this period saw Earth’s atmosphere suddenly bloom with (previously scarce) molecular oxygen. The rapid alteration of the atmosphere’s composition was nothing short of a cataclysm for some early lifeforms (at the time, mostly simple celled prokaryotes). Anaerobic species – those that dwell in oxygen-free environments – experienced a near extinction-level event. But the Great Oxidation was also an opportunity for other forms of life to thrive. Oxygen in the atmosphere tempered the planetary greenhouse effect, turning methane into the less potent carbon dioxide, and ushering in a series of ice ages known as the Huronian Glaciation. But oxygen is an energy-rich molecule, and it also bolstered diversity and activity on the planet, as a powerful new source of fuel for living organisms.
The cause of this dramatic event? The tiniest of creatures: little ocean-dwelling cyanobacteria (sometimes known as blue-green algae) that had developed a new super-power never before seen on planet Earth: photosynthesis. This unique ability – to gain energy from sunlight and release oxygen as a waste product – was a revolutionary step for so small a critter. It quite literally changed the world.
Continue reading “When Did Photosynthesis Begin?”
The Chicxulub impact event was an enormous catastrophe that left a huge imprint on the Earth’s surface. Not only did it cause the mass extinction of the dinosaurs, it left a crater 180 km (112 miles) in diameter, and deposited a worldwide layer of concentrated iridium in the Earth’s crust.
But a new study shows that the impact also left its mark deep underground, in the form of a vast hydrothermal system that modified a massive chunk of the Earth’s crust.
Continue reading “The Meteor Impact that Wiped Out the Dinosaurs Created a Vast Underground Hydrothermal System”
The building blocks of life can, and did, spontaneously assemble under the right conditions. That’s called spontaneous generation, or abiogenesis. Of course, many of the details remain hidden to us, and we just don’t know exactly how it all happened. Or how frequently it could happen.
Continue reading “Life Could be Common Across the Universe, Just Not in Our Region”
The last few years has seen an explosion of exoplanet discoveries. Some of those worlds are in what we deem the “habitable zone,” at least in preliminary observations. But how many of them will have life-supporting, oxygen-rich atmospheres in the same vein as Earth’s?
A new study suggests that breathable atmospheres might not be as rare as we thought on planets as old as Earth.
Continue reading “Science Fiction Might Be Right After All. There Might Be Breathable Atmospheres Across the Universe”
The question of how life first emerged here on Earth is a mystery that continues to
One of the more daunting aspects of the mystery has to do with peptides and enzymes, which fall into something of a “chicken and egg” situation. Addressing this, a team of researchers from the University College London (UCL) recently conducted a study that effectively demonstrated that peptides could have formed in conditions
The Earth wasn’t formed containing the necessary chemicals for life to begin. One well-supported theory, called the “late veneer theory”, suggests that the volatile chemicals needed for life arrived long after the Earth formed, brought here by meteorites. But a new study challenges the late veneer theory.
Evidence shows that the Moon was created when a Mars-sized planet named Theia collided with the Earth. The impact created a debris ring out of which the Moon formed. Now, this new study says that same impact may have delivered the necessary chemicals for life to the young Earth.
The idea of panspermia — that life on Earth originated from comets or asteroids bombarding our planet — is not new. But new research may have given the theory a boost. Scientists from Japan say their experiments show that early comet impacts could have caused amino acids to change into peptides, becoming the first building blocks of life. Not only would this help explain the genesis of life on Earth, but it could also have implications for life on other worlds.
Dr. Haruna Sugahara, from the Japan Agency for Marine-Earth Science and Technology in Yokahama, and Dr. Koichi Mimura, from Nagoya University said they conducted “shock experiments on frozen mixtures of amino acid, water ice and silicate (forsterite) at cryogenic condition (77 K),” according to their paper. “In the experiments, the frozen amino acid mixture was sealed into a capsule … a vertical propellant gun was used to [simulate] impact shock.”
They analyzed the post-impact mixture with gas chromatography, and found that some of the amino acids had joined into short peptides of up to 3 units long (tripeptides).
Based on the experimental data, the researchers were able to estimate that the amount of peptides produced would be around the same as had been thought to be produced by normal terrestrial processes (such as lighting storms or hydration and dehydration cycles).
The earliest known fossils on Earth are from about 3.5 billion years ago and there is evidence that biological activity took place even earlier. But there’s evidence that early Earth had little water and carbon-based molecules on the Earth’s surface, so how could these building blocks of life delivered to the Earth’s surface so quickly? This was also about the time of the Late Heavy Bombardment, and so the obvious answer could be the collision of comets and asteroids with the Earth, since these objects contain abundant supplies of both water and carbon-based molecules.
Space missions to comets are helping to confirm this possibility. The 2004 Stardust mission found the amino acid when it collected particles from Comet Wild 2. When NASA’s Deep Impact spacecraft crashed into Comet Tempel 1 in 2005, it discovered a mixture of organic and clay particles inside the comet. One theory about the origins of life is that clay particles act as a catalyst, allowing simple organic molecules to get arranged into more and more complex structures.
The news from the current Rosetta mission to comet 67P/Churyumov-Gerasimenko also indicates that comets are a rich source of materials, and more discoveries are likely to be forthcoming from that mission.
“Two key parts to this story are how complex molecules are initially generated on comets and then how they survive/evolve when the comet hits a planet like the Earth,” said Professor Mark Burchell from the University of Kent in the UK, commenting on the new research from Japan. “Both of these steps can involve shocks which deliver energy to the icy body… building on earlier work, Dr. Sugahara and Dr. Mimura have shown how amino acids on icy bodies can be turned into short peptide sequences, another key step along the path to life.”
“Comet impacts are normally associated with mass extinction on Earth, but this works shows that they probably helped kick-start the whole process of life in the first place,” said Sugahara. “The production of short peptides is the key step in the chemical evolution of complex molecules. Once the process is kick-started, then much less energy is needed to make longer chain peptides in a terrestrial, aquatic environment.”
The scientists also indicated that similar “kickstarting” could have happened in other places in our Solar System, such as on the icy moons Europa and Enceladus, as they likely underwent a similar comet bombardment.
Sugahara and Mimura presented their findings at the Goldschmidt geochemistry conference in Prague, going on this week.