New research done by Henrik Svensmark at the Danish National Space Center shows that data from microscopic fossil seashells can be used to define important features of our Galaxy about which astronomers have been very uncertain.
According to Dr Svensmark's report, published in Astronomische Nachrichten, the Sun and Earth travel together at a speed of 18 kilometres per second relative to the Milky Way's pattern of bright spiral arms. They last passed through a major spiral arm 34 million years ago. The density of matter is 80 per cent higher in the spiral arms than in the darker spaces between them. These and other numbers coming from the climatic analysis fall inside a wide range of previous suggestions, but the seashells tell the astronomers what the right numbers are, from a geological perspective. This is a surprising spin-off from Dr Svenmark's discovery that cosmic rays coming from exploded stars seem to have a big influence on the Earth's climate.
'Other experts have taken up our idea that cosmic rays cool the Earth by making it cloudier, and they have explained past alternations of hot and cold periods using the available astronomical data,' Dr Svensmark comments. 'Now I turn the reasoning around and calculate the astronomical data from the changes of climate over the past 200 million years.'
Nir Shaviv, an astrophysicist at the Racah Institute in Jerusalem, has argued that glacial episodes in the past 600 million years coincided with the passage of the Solar System through spiral arms of the Milky Way, where cosmic rays from exploded stars are particularly intense. Dr Shaviv has developed this astronomical approach to the climate in collaboration with a geologist, Ján Veizer of the University of Ottawa. Professor Veizer has amassed a long and detailed record of past variations in sea temperatures, using changes in the count of heavy oxygen atoms (O-18) in carbonate rocks formed by the microscopic fossils.
The chronicle of the rocks tells of major alternations of heat and cold over cycles of about 140 million years, corresponding with the intervals between spiral-arm crossings. Superimposed are warmer-cooler cycles of about 34 million years, due to vertical motions through the mid-plane of the Milky Way where the cosmic rays are most concentrated. While the Sun, with the Earth in tow, circles around the centre of the Galaxy, it also jumps up and dives down through the mid-plane, like a dolphin playing at the sea surface. In Dr Svensmark’s calculations, only one combination of key numbers describing the galactic environment gives the correct dolphin-like motions of the Sun needed to match the climate changes recorded by the microscopic shell-makers.
This is one of a number of new perspectives arising from the link between cosmic rays and climate. Recent experiments showing how the cosmic rays influence cloud formation were reported in DNSC press release 3 October 2006.
Sune Nordentoft Lauritsen | alfa
Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University
Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and Technology
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences