Conditions on Earth for the first 500 million years after it formed may have been surprisingly similar to the present day, complete with oceans, continents and active crustal plates. This alternate view of Earth’s first geologic eon, called the Hadean, has gained substantial new support from the first detailed comparison of zircon crystals that formed more than 4 billion years ago with those formed contemporaneously in Iceland, which has been proposed as a possible geological analog for early Earth.
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“If the Sun were less intense, Mercury would be within the habitable zone, and therefore life would have to adapt to strange light cycles,” said Sarah Brown, an astrobiologist at the United Kingdom Center for Astrobiology in Edinburgh, Scotland. Mercury has an oddball orbit — it takes longer for it to rotate on its axis and complete a day than it takes to orbit the sun and complete a year. Researchers suggest photosynthesis could take place on an alien planet with a similarly bizarre orbit, potentially helping support complex life.
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There is an ongoing drama in the Saturnian ring system that causes small moons to be born and then destroyed on time scales that are but an eyeblink in the history of the solar system. SETI Institute scientists Robert French and Mark Showalter have examined photos made by NASA’s Cassini spacecraft and compared them to 30 year-old pictures made by the Voyager mission. They find that there is a marked difference in the appearance of one of the rings, even over this cosmologically short interval, a difference that can be explained by the brief strut and fret of small moons.
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Over the history of the Earth, billions of football-sized rocks have landed on its surface, some only slightly heated by the launch, reaching Earth in a matter of a few months. Recent research on lunar rocks discovered in Antarctica has shown that rocks greater than 10 kilograms in mass could be ejected from terrestrial planets -rocks capable of carrying living microbes- and survive the searing violence of the launch.
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At a public lecture Einstein gave in Pittsburgh in 1934, four hundred students were present when Einstein mathematically derived his famous mass-energy equivalence equation: E=mc2. This is thought to be the only surviving photo that shows Einstein working on that derivation, pulled from a halftone newspaper clipping by David Topper and Dwight Vincent of the University of Winnipeg, who discovered it in 2007.
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Around 12,800 years ago, a sudden, catastrophic event plunged much of the Earth into a period of cold climatic conditions and drought. This drastic climate change—the Younger Dryas—coincided with the extinction of Pleistocene megafauna, such as the saber-tooth cats and the mastodon, and resulted in major declines in prehistoric human populations, including the termination of the Clovis culture. A new study published in The Journal of Geology provides support for the theory that a cosmic impact event over North America some 13,000 years ago caused a major period of climate change known as the Younger Dryas stadial, or “Big Freeze.”
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Planet Venus, with its thick atmosphere made of carbon dioxide, its parched surface, and pressures so high that landers are crushed within a few hours, offers scientists a chance to study a planet very foreign to our own. Mysterious holes in the planet's ionosphere provide additional clues to understanding Venus's atmosphere, how the planet interacts with the constant onslaught of solar wind from the sun, and perhaps even what's lurking deep in its core.
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Astronomers searching the atmospheres of alien worlds for gases that might be produced by life can't rely on the detection of just one type, such as oxygen, ozone, or methane, because in some cases these gases can be produced non-biologically, according to extensive simulations by researchers in the NASA Astrobiology Institute’s Virtual Planetary Laboratory.
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Kepler researchers want to understand how terrestrial planets like Venus, Earth and Mars and gas giant planets like Jupiter are distributed in planetary systems around other stars. Understanding how planetary systems form and where different types of planets form can shed light on whether our solar system is unique, or more likely, is a "standard" form of planetary system formation.
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Quasars are supermassive black holes that live at the center of distant massive galaxies. They shine as the most luminous beacons in the sky across the entire electromagnetic spectrum by rapidly accreting matter into their gravitationally inescapable centers. New work from Carnegie’s Hubble Fellow Yue Shen and Luis Ho of the Kavli Institute for Astronomy and Astrophysics (KIAA) at Peking University solves a quasar mystery that astronomers have been puzzling over for 20 years. Their work, published in the September 11 issue of Nature, shows that most observed quasar phenomena can be unified with two simple quantities: one that describes how efficiently the hole is being fed, and the other that reflects the viewing orientation of the astronomer.
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