Meteorites Study: Mars, Earth, Moon Grew Up In Unique Planetary Nursery

March 20, 2008

A study of meteorites suggests that Mars, the Earth and the Moon share a common composition from ‘growing up’ in a unique planetary nursery in the inner solar system. The finding could lead to a rethink of how the inner solar system formed.

In the journal Nature the international team of scientists, which includes Professor Alex Halliday from Oxford University’s Department of Earth Sciences, report how they analysed 16 meteorites that fell to Earth from Mars. They found that the amounts of neodymium-142 these contain are subtly different from those of objects found in the asteroid belt. This isotopic fingerprint is proof that the chemistry of the inner solar system was different even for elements that are hard to vapourise.

Professor Halliday said: ‘The Earth, Moon and Mars appear to have formed in a part of the inner solar system with a ratio of samarium to neodymium that is around 5 per cent more than could be found in the asteroid belt. It is this ‘family resemblance’ that we see today when we compare oceanic basalts from Earth with Moon rocks and Martian meteorites. Such differences may be the result of the erosion of planetary crusts during formation events, alternatively, this composition arose from the sorting of clouds of partially melted droplets or grains - known as ‘chondrules’.’

Earth has a long geological history of recycling the materials that make up its crust and mantle, which could help explain why its composition is different from that of other planetary bodies – it could, for example, have deeply buried reservoirs of certain elements. However Mars and the Moon are believed to have been nothing like as active during their lifespan: making it much more difficult for any theory involving material recycling to explain why their composition should differ from other planetary bodies and yet have such similarities with the composition of the Earth.

Professor Halliday said: ‘What our results suggest is that the sorting of the elements that make up these planets may have happened at a much earlier stage than had been believed. It may even be that this sorting happened in the accretion disk out of which Mars and the early Earth first formed. What we can say is that the composition of these worlds is inconsistent with them simply forming out of large ‘lumps’ of stony meteorites, like those we see today in the asteroid belt.’

A report of the research, entitled ‘Super-chondritic Sm/Nd in Mars, Earth and the Moon’, is published in Nature on 20 March 2008. Co-author Alex Halliday is Professor of Geochemistry at Oxford University’s Department of Earth Sciences and Head of the MPLS Division. The international team included scientists from the Universite Denis Diderot, France, the ETH Zurich, Switzerland and the Ecole Normale Superieure de Lyon, France.

Source: Oxford University

Explore further: The moon

Related Stories

The moon

September 21, 2015

Look up in the night sky. On a clear night, if you're lucky, you'll catch a glimpse of the moon shining in all it's glory. As Earth's only satellite, the moon has orbited our planet for over three and a half billion years. ...

What are asteroids made of?

September 14, 2015

What are asteroids made of? Asteroids are made mostly of rock—with some composed of clay and silicate—and different metals, mostly nickel and iron. But other materials have been found in asteroids, as well.

The gas (and ice) giant Neptune

September 14, 2015

Neptune is the eight planet from our Sun, one of the four gas giants, and one of the four outer planets in our Solar System. Since the "demotion" of Pluto by the IAU to the status of a dwarf planet – and/or Plutoid and ...

What are asteroids?

September 10, 2015

4.6 billion years ago, our solar system formed from a collection of gas and dust surrounding our nascent sun. While much of the gas and dust in this protoplanetary disk coalesced to form the planets, some of the debris was ...

Recommended for you

How to prepare for Mars? NASA consults Navy sub force

October 5, 2015

As NASA contemplates a manned voyage to Mars and the effects missions deeper into space could have on astronauts, it's tapping research from another outfit with experience sending people to the deep: the U.S. Navy submarine ...

Researchers find a new way to weigh a star

October 5, 2015

Researchers from the University of Southampton have developed a new method for measuring the mass of pulsars – highly magnetised rotating neutron stars formed from the remains of massive stars after they explode into supernovae.

NASA selects investigations for future key planetary mission

October 1, 2015

NASA has selected five science investigations for refinement during the next year as a first step in choosing one or two missions for flight opportunities as early as 2020. Three of those chosen have ties to NASA's Jet Propulsion ...


Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Mar 20, 2008
It seems to me that the accretion disk which formed the all planets might have been sorted by gravity during the period of planetary formation. Is this what Halliday et al is proposing?
3 / 5 (2) Mar 21, 2008
What Halliday suggests is that there was in fact some sorting of the elements in the acretion disk before the formation of certain planetary bodies, and that Mars, Earth & our moon where all born from the same portion of said disk subsequent to such sorting.

As for the mechanism that caused said sorting, he does not seem to be suggesting any particular one.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.