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Stress genes help carnivore plants kill
REUTERS/CARLO ALLEGRI
IN BRIEF Trees trap moth inside fruit for year
Sun’s rotation is slowed down by its own photons THE sun is hoist with its own petard. Its outermost layer frustrates photons of light trying to escape. Now it seems that when light does eventually stream away, it may in turn slow down the sun’s rotation. While the interior of the sun rotates like a solid sphere, the outer layers do not: the polar regions turn slower than the equator, and the layers closer to the core rotate faster than the outermost 5 per cent. But it’s not clear why. Even within the photosphere – the thin layer we see as the surface of the sun – there is a hint of a difference between the top layers and the bottom.
There is a possible explanation. Photons created in the sun’s interior bounce around on their way out, gaining a small amount of momentum from each atom they ricochet off. When a photon leaves the photosphere thousands to millions of years later, it carries that momentum with it. The photosphere, meanwhile, experiences a backward push. To test this theory, Jeff Kuhn at the University of Hawaii in Pukulani and colleagues used data from NASA’s Solar Dynamics Observatory to measure the edge of the photosphere and its rotation. They calculated that over the sun’s lifetime, those ricocheting photons would cause a slowdown of about 3 per cent in the rotation of the outermost 100 kilometres of the sun, and exert a drag on the outermost 5 per cent (arxiv.org/abs/1612.00873).
Spacecraft may use starlight to park WE’RE dreaming up technologies to travel quickly to other star systems, but how do we apply the brakes on arrival? Rene Heller of the Max Planck Institute for Solar System Research and independent researcher Michael Hippke have an answer: we can slow a spacecraft using the stars themselves. The nearest star system, Alpha Centauri, is more than 4 light
years away. Chemical propulsion would take 100,000 years to get us there, but ultra-light solar sails could help an interstellar probe reach the system – including the Earth-mass planet orbiting its companion star, Proxima Centauri – in just 20 years. Unfortunately, at that speed, the craft would whizz through the whole system in just a few hours. “It’s hardly enough time to take in
the view, let alone do serious science,” says Heller. Now, Hippke and Heller show that a combination of the stars’ gravity and radiation pressure from their photons can bring the craft into a stable orbit around one of the stars, then around the tantalising planet (Astrophysical Journal Letters, doi.org/bx8t). The idea is “scientifically viable and very interesting”, says Avi Loeb at Harvard University, though he has practical concerns.
SOME relationships are a little stifling. One East Asian tree is so intimate with the moth that pollinates it that it holds the moth’s offspring captive until they reach adulthood. In April and May, one species of leafflower moth, Epicephala lanceolaria, lays its eggs in the flowers of the Glochidion lanceolarium leafflower tree – pollinating it along the way. But unlike other leafflower trees, G. lanceolarium does not bear fruit until January the following year. Only at this point do the larvae emerge from their eggs and begin to feed on the fruit. With their development squeezed into a few months, the larvae metamorphose into adults while still inside the fruit. In March, the fruits mature – and the moths fly out, just in time to mate and lay their eggs in the tree’s new blooms (The American Naturalist, doi.org/bx8w).
Stress genes help carnivore plants kill DIFFERENT pitcher plants took similar evolutionary paths in order to trap and digest insects. Genetic sequencing of three families of pitcher plants from the Americas, Asia and Australia shows that they all repurposed genes normally involved in the stress response to make the insect-killing fluids in their pitcher-shaped leaves (Nature, doi.org/bzb5). “It’s a big, complicated series of events at the evolutionary level to become carnivorous,” says Victor Albert at the State University of New York at Buffalo. The fact that all these plants use the same genes suggests the paths plants can take to become predators are limited, or that this is the quickest path to their unusual lifestyle. 11 February 2017 | NewScientist | 19
IN BRIEF Trees trap moth inside fruit for year
Sun’s rotation is slowed down by its own photons THE sun is hoist with its own petard. Its outermost layer frustrates photons of light trying to escape. Now it seems that when light does eventually stream away, it may in turn slow down the sun’s rotation. While the interior of the sun rotates like a solid sphere, the outer layers do not: the polar regions turn slower than the equator, and the layers closer to the core rotate faster than the outermost 5 per cent. But it’s not clear why. Even within the photosphere – the thin layer we see as the surface of the sun – there is a hint of a difference between the top layers and the bottom.
There is a possible explanation. Photons created in the sun’s interior bounce around on their way out, gaining a small amount of momentum from each atom they ricochet off. When a photon leaves the photosphere thousands to millions of years later, it carries that momentum with it. The photosphere, meanwhile, experiences a backward push. To test this theory, Jeff Kuhn at the University of Hawaii in Pukulani and colleagues used data from NASA’s Solar Dynamics Observatory to measure the edge of the photosphere and its rotation. They calculated that over the sun’s lifetime, those ricocheting photons would cause a slowdown of about 3 per cent in the rotation of the outermost 100 kilometres of the sun, and exert a drag on the outermost 5 per cent (arxiv.org/abs/1612.00873).
Spacecraft may use starlight to park WE’RE dreaming up technologies to travel quickly to other star systems, but how do we apply the brakes on arrival? Rene Heller of the Max Planck Institute for Solar System Research and independent researcher Michael Hippke have an answer: we can slow a spacecraft using the stars themselves. The nearest star system, Alpha Centauri, is more than 4 light
years away. Chemical propulsion would take 100,000 years to get us there, but ultra-light solar sails could help an interstellar probe reach the system – including the Earth-mass planet orbiting its companion star, Proxima Centauri – in just 20 years. Unfortunately, at that speed, the craft would whizz through the whole system in just a few hours. “It’s hardly enough time to take in
the view, let alone do serious science,” says Heller. Now, Hippke and Heller show that a combination of the stars’ gravity and radiation pressure from their photons can bring the craft into a stable orbit around one of the stars, then around the tantalising planet (Astrophysical Journal Letters, doi.org/bx8t). The idea is “scientifically viable and very interesting”, says Avi Loeb at Harvard University, though he has practical concerns.
SOME relationships are a little stifling. One East Asian tree is so intimate with the moth that pollinates it that it holds the moth’s offspring captive until they reach adulthood. In April and May, one species of leafflower moth, Epicephala lanceolaria, lays its eggs in the flowers of the Glochidion lanceolarium leafflower tree – pollinating it along the way. But unlike other leafflower trees, G. lanceolarium does not bear fruit until January the following year. Only at this point do the larvae emerge from their eggs and begin to feed on the fruit. With their development squeezed into a few months, the larvae metamorphose into adults while still inside the fruit. In March, the fruits mature – and the moths fly out, just in time to mate and lay their eggs in the tree’s new blooms (The American Naturalist, doi.org/bx8w).
Stress genes help carnivore plants kill DIFFERENT pitcher plants took similar evolutionary paths in order to trap and digest insects. Genetic sequencing of three families of pitcher plants from the Americas, Asia and Australia shows that they all repurposed genes normally involved in the stress response to make the insect-killing fluids in their pitcher-shaped leaves (Nature, doi.org/bzb5). “It’s a big, complicated series of events at the evolutionary level to become carnivorous,” says Victor Albert at the State University of New York at Buffalo. The fact that all these plants use the same genes suggests the paths plants can take to become predators are limited, or that this is the quickest path to their unusual lifestyle. 11 February 2017 | NewScientist | 19