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 Neutron star merger directly observed for the first time
17.10.2017 | University of Maryland

nachricht Breaking: the first light from two neutron stars merging
17.10.2017 | American Association for the Advancement of Science

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Ocean atmosphere rife with microbes

17.10.2017 | Life Sciences

Neutrons observe vitamin B6-dependent enzyme activity useful for drug development

17.10.2017 | Life Sciences

NASA finds newly formed tropical storm lan over open waters

17.10.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>