Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The microscopic hitchhikers' guide to the Galaxy

15.11.2006
As the Earth roams through the Milky Way like a spaceship, shelly inhabitants of the sea act as natural sensors that record the ever-changing cosmic environment over many millions of years.

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
Further information:
http://www.spacecenter.dk

More articles from Physics and Astronomy:

nachricht Ultra-compact phase modulators based on graphene plasmons
27.06.2017 | ICFO-The Institute of Photonic Sciences

nachricht Smooth propagation of spin waves using gold
26.06.2017 | Toyohashi University of Technology

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Touch Displays WAY-AX and WAY-DX by WayCon

27.06.2017 | Power and Electrical Engineering

Drones that drive

27.06.2017 | Information Technology

Ultra-compact phase modulators based on graphene plasmons

27.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>