Nav: Home

'Faster-ticking clock' indicates early solar system may have evolved faster than we think

May 01, 2012

Jerusalem, April 30, 2012 - Our solar system is four and a half billion years old, but its formation may have occurred over a shorter period of time than we previously thought, says an international team of researchers from the Hebrew University of Jerusalem and universities and laboratories in the US and Japan..

Establishing chronologies of past events or determining ages of objects require having clocks that tick at different paces, according to how far back one looks. Nuclear clocks, used for dating, are based on the rate of decay of an atomic nucleus expressed by a half-life, the time it takes for half of a number of nuclei to decay, a property of each nuclear species.

Radiocarbon dating for example, invented in Chicago in the late 1940s and refined ever since, can date artifacts back to prehistoric times because the half-life of radiocarbon (carbon-14) is a few thousand years. The evaluation of ages of the history of earth or of the solar system requires extremely "slow-paced" chronometers consisting of nuclear clocks with much longer half-lives.

The activity of one of these clocks, known as nucleus samarium-146 (146Sm), was examined by Michael Paul, the Kalman and Malke Cooper Professor of Nuclear Physics at the Hebrew University of Jerusalem, as well as researchers from the University of Notre Dame and the Argonne National Laboratory in the US and from two Japanese universities.

146Sm belongs to a family of nuclear species which were "live" in our sun and its solar system when they were born. Events thereafter, and within a few hundred million years, are dated by the amount of 146Sm that was left in various mineral archives until its eventual "extinction."

146Sm has become the main tool for establishing the time evolution of the solar system over its first few hundred million years. This by itself owes to a delicate geochemical property of the element samarium, a rare element in nature. It is a sensitive probe for the separation, or differentiation, of the silicate portion of earth and of other planetary bodies.

The main result of the work of the international scientists, detailed in a recent article in the journal Science, is a new determination of the half-life of 146Sm, previously adopted as 103 million years, to a much shorter value of 68 million years. The shorter half-life value, like a clock ticking faster, has the effect of shrinking the assessed chronology of events in the early solar system and in planetary differentiation into a shorter time span.

The new time scale, interestingly, is now consistent with a recent and precise dating made on a lunar rock and is in better agreement with the dating obtained with other chronometers.

The measurement of the half-life of 146Sm, performed over several years by the collaborators, involved the use of the ATLAS particle accelerator at Argonne National Laboratory in Illinois.


The Hebrew University of Jerusalem
From rocks in Colorado, evidence of a 'chaotic solar system'
Plumbing a 90 million-year-old layer cake of sedimentary rock in Colorado, a team of scientists from the University of Wisconsin-Madison and Northwestern University has found evidence confirming a critical theory of how the planets in our solar system behave in their orbits around the sun.
Why are there different 'flavors' of iron around the Solar System?
New work from Carnegie's Stephen Elardo and Anat Shahar shows that interactions between iron and nickel under the extreme pressures and temperatures similar to a planetary interior can help scientists understand the period in our Solar System's youth when planets were forming and their cores were created.
Does our solar system have an undiscovered planet? You can help astronomers find out
ASU's Adam Schneider and colleagues are hunting for runaway worlds in the space between stars, and citizen scientists can join the search with a new NASA-funded website.
Rare meteorites challenge our understanding of the solar system
Researchers have discovered minerals from 43 meteorites that landed on Earth 470 million years ago.
New evidence on the formation of the solar system
International research involving a Monash University scientist is using new computer models and evidence from meteorites to show that a low-mass supernova triggered the formation of our solar system.
Planet Nine could spell doom for solar system
The solar system could be thrown into disaster when the sun dies if the mysterious 'Planet Nine' exists, according to research from the University of Warwick.
Theft behind Planet 9 in our solar system
Through a computer-simulated study, astronomers at Lund University in Sweden show that it is highly likely that the so-called Planet 9 is an exoplanet.
Studying the solar system with NASA's Webb Telescope
NASA's James Webb Space Telescope will look across vast distances to find the earliest stars and galaxies and study the atmospheres of mysterious worlds orbiting other stars.
'This solar system isn't big enough for the both of us.' -- Jupiter
It's like something out of an interplanetary chess game. Astrophysicists at the University of Toronto have found that a close encounter with Jupiter about four billion years ago may have resulted in another planet's ejection from the Solar System altogether.
IBEX sheds new light on solar system boundary
In 14 papers published in the October 2015 Astrophysical Journal Supplement, scientists present findings from NASA's Interstellar Boundary Explorer, or IBEX, mission providing the most definitive analyses, theories and results about local interstellar space to date.

Best Science Podcasts 2017

We have hand picked the best science podcasts for 2017. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.

Now Playing: Radiolab

Truth Trolls
Today, a third story of folks relentlessly searching for the truth. But this time, the truth seekers are an unlikely bunch... internet trolls.

Now Playing: TED Radio Hour

Rethinking School
For most of modern history, humans have placed smaller humans in institutions called schools. But what parts of this model still work? And what must change? This hour, TED speakers rethink education.TED speakers include teacher Tyler DeWitt, social entrepreneur Sal Khan, international education expert Andreas Schleicher, and educator Linda Cliatt-Wayman.