Carbon from a Cosmic Collision?
Scientists have long wondered how carbon-based life developed on Earth since most of the carbon on our planet should have either vaporized into space during the early molten days of Earth or have become locked in the Earth’s core. Now, research by scientists at Rice University suggests a cosmic explanation: that almost all of the carbon on our planet could have come from a collision between Earth and an embryonic planet some 4.4 billion years ago. One popular theory was that volatile elements such as carbon, sulfur, nitrogen, and hydrogen were added after Earth finished forming, and that any of these elements that fell to Earth in meteorites and comets could have then avoided the intense heat in previous eras of the planet. But while that theory could account for the abundance of volatile elements, there are no known meteorites that would produce the ratio of these elements in the silicate portion of Earth. The researchers turned their attention to our planetary neighbors and conducted experiments to determine how sulfur or silicon might change the affinity of iron for carbon. They began examining alloys rich in sulfur and silicon, in part because Mars is thought to be sulfur-rich and the core of Mercury is believed to be abundant in silicon. Their investigation revealed that carbon could be excluded from the core and relegated to the silicate mantle if the iron alloys within the core were rich in either silicon or sulfur. Thus, if an embryonic planet resembling Mercury that had already formed a silicon-rich core had collided with Earth and had been absorbed by our planet, the interaction could have led to the core of that planet going directly into the core of Earth, and the carbon-rich mantle mixing with the mantle of Earth. Researchers will continue to explore the sources of all the volatile elements, but this theory is a strong explanation for the abundance of Earth’s carbon and sulfur.
Credit: ESO/F. Ferraro
A Rare Relic of Early Milky Way Found
The discovery of a fossilized remnant of the early Milky Way that is harboring stars of vastly different ages may provide astronomers a way to better understand how galaxies form and evolve. An international team of astronomers has found that Terzan 5, a stellar system 19,000 light-years from Earth that has been classified as a globular cluster for 40 years since it was first discovered, contains stars that are similar to the most ancient stars in the Milky Way. By examining data from several ground-based telescopes as well as the Advanced Camera for Surveys and the Wide Field Camera 3 on board Hubble, the researchers uncovered evidence of the existence of two distinct kinds of stars in Terzan 5. They discovered that these stars not only contain different elements, but are of different ages—a gap as large as around 7 billion years. This vast age gap in the stars suggest that the star formation process in Terzan 5 was not continuous, but rather characterized by two distinct bursts of star formation. This finding suggests that Terzan 5 may be a surviving witness of the Galactic bulge assembly process, and a link between the local and distant Universe.
Juno Reveals Jupiter’s North Pole
The first images of Jupiter’s north pole, taken by NASA’s Juno during its first flyby of the planet with its instruments on, reveal storm systems and weather activity that is unlike anything seen before on any of our solar system's gas-giant planets. The pictures reveal that the north pole is much bluer than other parts of the planet, and that there are a lot of storms. Scientists also saw clouds—a possible indication that the clouds are at a higher altitude than other features. And The Jovian Infrared Auroral Mapper (JIRAM) instrument on Juno, which is supplied by the Italian Space Agency, has captured informative infrared images of Jupiter that reveal warm and hot spots at its north and south polar regions that have never been seen before.
Featured image credit: A. Passwaters/Rice University based on original courtesy of NASA/JPL-Caltech
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