A European spacecraft that has been peering through the thick, roiling clouds of Venus for the past three years has found further evidence that the inhospitable planet once had oceans, volcanoes, and a system of plate tectonics similar to those at work on Earth. The Venus Express has mapped the planet’s southern hemisphere using infrared imaging, and found heat variations in the surface rocks, which allows researchers to speculate on the chemical composition of those rocks. Different surfaces radiate different amounts of heat at infrared wavelengths due to a material characteristic known as emissivity, which varies in different materials [SPACE.com].
In certain highland areas, researchers detected cooler patches of rock whose thermal signatures resemble those of granites on Earth. On our own planet, granites are made during the process of rock recycling that goes on at the edges of the great geologic plates that cover the Earth. At the boundaries of these plates, ancient rock is pulled deep into the planet, reworked with water and then re-surfaced at volcanoes. Critically, then, if there is granite on Venus, there must also have been an ocean and a process of plate movement in the past [BBC News].
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Is planetary Armageddon just a matter of time? Will Earth meet its fiery doom when the orbits of the planets in our solar system become destabilized, leading Mars, Mercury, or Venus to crash into our home turf? A new study predicts that there is indeed a very slim possibility that such a cataclysm will rock our world, but notes that the possible collisions wouldn’t happen for more than 3 billion years, by which time humans may be long gone. “I see the results as a case of the glass being 99 percent full and 1 percent empty…. While it’s possible that a collision could occur billions of years from now, it’s actually very unlikely” [SPACE.com], says Gregory Laughlin, an astronomer who wasn’t involved in the current research.
Astronomers had thought that the orbits of the planets were predictable. But 20 years ago, researchers showed that there were slight fluctuations in their paths. Now, the team has shown how in a small proportion of cases these fluctuations can grow until after several million years, the orbits of the inner planets begin to overlap [BBC News]. The researchers simulated the interactions of the eight major planets, Pluto, and the moon over the course of 5 billion years, up until our sun is expected to expand into a red giant. The simulation, described in the study published in Nature, covered more than 2,500 possible futures.
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The planet Venus may not have always been the hot and barren ball of rock that we see today. A new analysis of its surface indicates that it might once have had oceans of liquid water–which could have allowed for a brief flourishing of microbial life.
Researchers examined nighttime infrared emissions coming from Venus’ surface, and found that the planet’s highland regions emit less infrared radiation than its lowland regions. One interpretation of this lower infrared emission from the highlands, say the authors, is that they are composed largely of ‘felsic’ rocks, particularly granite. Granite, which on Earth is found in continental crust, requires water for its formation…. “This is the first direct evidence that early in the history of the Solar System, Venus was a habitable planet with plenty of water,” says [astrobiologist] Dirk Schulze-Makuch…. “The question is how long Venus remained habitable. But this gives new impetus for the search for microbial life in Venus’s lower atmosphere” [Nature News].
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