What set the stage for the emergence of life on early Earth? There will never be a single answer to that question, but there are many partial answers related to the global forces at play during that period. Two of those globe-shaping dynamics are the rise of the magnetic fields that protected Earth from hazardous …
Continue reading "Clues About Conditions on Early Earth As Life Was Emerging"
The presence of life brings many unexpected consequences. On Earth, for instance, when cyanobacteria spread widely in ancient oceans more than two billion years ago, their production of increasingly large amounts of oxygen killed off much of the other anaerobic life present at the day because oxygen is a toxin, unless an organism finds ways …
As scientists work to understand what might make a distant planet habitable, one factor that is getting attention is the shape of the planet's orbit, how "eccentric" it might be. It might seem that a perfect circular orbit would be ideal for habitability because it would provide stability, but a new model suggests that it …
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All of life, from simplest to most complex, contains five information-passing compounds that allow the genetic code to work. These nitrogen-based compounds, called nucleobases, are found in all the the DNA and RNA that provide the instructions to build and operate every living thing on Earth. How these compounds are formed, or where they come …
The Hayabusa2 sample return capsule returning to Earth. The bright streak in the sky is the capsule, shock heated as it enters the Earth's atmosphere. The bright lights on the ground are buildings. (JAXA) In the early hours of December 6, 2020, what appeared to be a shooting star blazed across the sky above the …
An oblique radar view of the largest "pack ice" block in the Venus lowlands identified by Byrne et al. (Paul Byrne, based on original NASA/JPL imagery). The two Earth-sized planets in our solar system have taken wildly different evolutionary routes. The surface of the Earth became a temperate utopia for a liquid water and a …
Continue reading "The Surface of Venus Was Thought to Be Stagnant. But This May Not Be True"
Scientists have long held that many of the important compounds and elements that make life possible on Earth arrived here after the planet was formed and was orbiting the sun. These molecules came via meteorites and comets, it was thought, from the colder regions beyond Jupiter. But in a challenge to that long-accepted view, a …
Continue reading "New Insights Into How Earth Got Its Nitrogen"
When our sun was young, it was significantly less luminous and sent out significantly less warming energy than it does now. Scientists estimate that 4 million years ago, when the sun and our solar system were 500 million years old, the energy that the sun produced and dispersed was about 75 percent of what it …
One of the enduring puzzles of our planet is why it is so wet. Since Earth formed relatively close to the sun, planetary scientists have generally held that any of the water in the building blocks of early-forming Earth was baked out and so was unavailable to make oceans or our atmosphere. That led to …
Continue reading "An “Elegant” New Theory on How Earth Became a Wet Planet"
Deep inside the rocky planets of our solar system, as well as some solar system moons, is an iron-based core. Some, such as Earth's core, have an inner solid phase and outer molten phase, but the solar system cores studied so far are of significantly varied sizes and contain a pretty wide variety of elements …
Many Worlds 