On the horizon
Bid for powerful telescope narrows
Australia and South Africa are the last countries standing in a bid to host a new radio telescope array 50 times more sensitive than the most powerful radio telescopes today. If South Africa gets the final nod for this square-kilometer array, it would cement the country's role as southern Africa's portal to the cosmos. The country currently hosts the Southern African Large Telescope, an international, 11-meter (36-foot) behemoth 200 miles outside Capetown.
The new radiotelescope array will consist of several thousand antennas spread over 1,900 miles. Half of the antennas would be in a core three miles across. Outlying antennas would be in Botswana, Namibia, Mozambique, Madagascar, Mauritius, Kenya, and Ghana.
The radiotelescope's exquisite sensitivity would let it pick up signals from the formation of the first stars, map the influence of magnetic fields on star formation, and help solve other cosmic puzzles. A final decision on siting is expected toward the end of the decade.
It's a fish tale that might have been hard to believe until now: The denizens of the deep appear to play an unexpectedly large role as marine MixMasters. Experiments suggest that these organisms stir the water with enough energy to play a key role in drawing nutrient-rich waters from the depths to the surface layer, where other organisms feed. This mixing also plays a role in drawing gases such as carbon dioxide out of the atmosphere and into the ocean.
Theoretical calculations had suggested that creatures – from no-see-um zooplankton 0.2 inches long to 30-foot whales – can act as local blenders as they swim. The calculations implied that critters on the move, especially in schools, could generate local turbulence 1,000 to 10,000 times more intense than would otherwise occur. Indeed, some have speculated that biologically driven turbulence could provide a significant source of energy driving the oceans' large-scale circulation.
A team from Victoria University in Canada took instruments to British Columbia's Saanich Inlet, a small fjord, to test the idea on local krill. The krill move up from the depths at dusk to feed near the surface. As the krill moved past the instruments, turbulence skyrocketed 1,000 to 10,000 times higher than daytime readings. This activity led to mixing between ocean layers that on average was 100 times greater at dusk than during the day. The results are in the current issue of the journal Science.
Astronomers combing through Hubble Space Telescope images have found a mother lode of fledgling galaxies dating back to when the universe was about a billion years old. Finding just one galaxy from that period would have been worth the effort, astronomers say. But a group led by Rychard Bouwens, an astronomer at the University of California at Santa Cruz, found 500 of them.
The galaxies are small, and many of them dim, suggesting that they are early building blocks for large galaxies. But they also are blue, indicating that they are producing at a prodigious pace young, massive stars from the large amounts of hydrogen formed during the Big Bang, an enormous release of energy that gave rise to the universe.
The find "highlights a period of fundamental change in the universe, and we are seeing the galaxy population that brought about that change," notes Garth Illingworth, a member of the research team. During this period, the stars in these galaxies helped reheat and light up the universe, which underwent a cold, dark period between the end of the Big Bang and the emergence of the first stars and galaxies. The results will be published in an upcoming issue of the Astrophysical Journal.
