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Accretion left the terrestrial planets depleted in volatile components. Here I examine evidence for the hypothesis that the Moon and the Earth were essentially dry immediately after the formation of the Moon—by a giant impact on the proto-Earth—and only much later gained volatiles through accretion of wet material delivered from beyond the asteroid belt. This view is supported by U–Pb and I–Xe chronologies, which show that water delivery peaked ∼100 million years after the isolation of the Solar System. Introduction of water into the terrestrial mantle triggered plate tectonics, which may have been crucial for the emergence of life. This mechanism may also have worked for the young Venus, but seems to have failed for Mars. [ABSTRACT FROM AUTHOR]

Chlorine in the Earth is highly depleted relative to carbonaceous chondrites and solar abundances. Knowledge of the Cl concentrations and distribution on Earth is essential for understanding the origin of these depletions. Large differences in the stable chlorine isotope ratios of meteoritic, mantle and crustal materials have been used as evidence for distinct reservoirs in the solar nebula and to calculate the relative proportions of Cl in the mantle and crust. Here we report that large isotopic differences do not exist, and that carbonaceous chondrites, mantle and crust all have the same 37Cl/35Cl ratios. We have further analysed crustal sediments from the early Archaean era to the Recent epoch and find no systematic isotopic variations with age, demonstrating that the mantle and crust have always had the same δ37Cl value. The similarity of mantle, crust and carbonaceous chondrites establishes that there were no nebular reservoirs with distinct isotopic compositions, no isotopic fractionation during differentiation of the Earth and no late (post-core formation) Cl-bearing volatile additions to the crustal veneer with a unique isotopic composition. [ABSTRACT FROM AUTHOR]

The origins of the building blocks of the Solar System can be studied using the isotopic composition of early planetary and meteoritic material. Oxygen isotopes in planetary materials show variations at the per cent level that are not related to the mass of the isotopes; rather, they result from the mixture of components having different nucleosynthetic or chemical origins. Isotopic variations reaching orders of magnitude in minute meteoritic grains are usually attributed to stellar nucleosynthesis before the birth of the Solar System, whereby different grains were contributed by different stars. Here we report the discovery of abundant silica-rich grains embedded in meteoritic organic matter, having the most extreme 18O/16O and 17O/16O ratios observed (both ∼10-1) together with a solar silicon isotopic composition. Both O and Si isotopes indicate a single nucleosynthetic process. These compositions can be accounted for by one of two processes: a single exotic evolved star seeding the young Solar System, or irradiation of the circumsolar gas by high energy particles accelerated during an active phase of the young Sun. We favour the latter interpretation, because the observed compositions are usually not expected from nucleosynthetic processes in evolved stars, whereas they are predicted by the selective trapping of irradiation products. [ABSTRACT FROM AUTHOR]

The abundances of elements and their isotopes in our Galaxy show wide variations, reflecting different nucleosynthetic processes in stars and the effects of Galactic evolution. These variations contrast with the uniformity of stable isotope abundances for many elements in the Solar System, which implies that processes efficiently homogenized dust and gas from different stellar sources within the young solar nebula. However, isotopic heterogeneity has been recognized on the subcentimetre scale in primitive meteorites, indicating that these preserve a compositional memory of their stellar sources. Small differences in the abundance of stable molybdenum isotopes in bulk rocks of some primitive and differentiated meteorites, relative to terrestrial Mo, suggest large-scale Mo isotopic heterogeneity between some inner Solar System bodies, which implies physical conditions that did not permit efficient mixing of gas and dust. Here we report Mo isotopic data for bulk samples of primitive and differentiated meteorites that show no resolvable deviations from terrestrial Mo. This suggests efficient mixing of gas and dust in the solar nebula at least to 3?au from the Sun, possibly induced by magnetohydrodynamic instabilities. These mixing processes must have occurred before isotopic fractionation of gas-phase elements and volatility-controlled chemical fractionations were established. [ABSTRACT FROM AUTHOR]

Chondrules are millimetre-sized spherules (mostly silicate) that dominate the texture of primitive meteorites. Their formation mechanism is debated, but their sheer abundance suggests that the mechanism was both energetic and ubiquitous in the early inner Solar System. The processes suggested—such as shock waves, solar flares or nebula lightning—operate on different length scales that have been hard to relate directly to chondrule properties. Chondrules are depleted in volatile elements, but surprisingly they show little evidence for the associated loss of lighter isotopes one would expect. Here we report a model in which molten chondrules come to equilibrium with the gas that was evaporated from other chondrules, and which explains the observations in a natural way. The regions within which the chondrules formed must have been larger than 150–6,000 km in radius, and must have had a precursor number density of at least 10 m-3. These constraints probably exclude nebula lightning, and also make formation far from the nebula midplane problematic. The wide range of chondrule compositions may be the result of different combinations of the local concentrations of precursors and the local abundance of water ice or vapour. [ABSTRACT FROM AUTHOR]

The article reports on the findings of the study concerning the tungsten-isotope measurement of lunar rocks and formation of the moon. It reveals that the moon comprises 30 percent of the Earth's mass and it's crust was formed 70-150 million years after the accretion of solar system. It is believed that the moon was formed 62-90 million years after the solar system and 16 million years after the Earth's core and lunar crust. Furthermore, the findings support the slower rate of magma-ocean solidification obtained from the samarium and neodymium data.

This article informs that the existence or radioactive aluminium and other short-lived nuclides in the early solar system suggests a source of heat for melting planetesimals, and provides a way of deducing time differences between events. It also means that some stellar process must have created significant amounts of aluminium just before the solar system formed. It is further informed that of the objects found inside chondrites, two have particular significance in the early history of the solar system: calcium aluminium refractory inclusions (CAIs) and chondrules. CAIs are the earliest object yet identified that bear clear isotopic evidence of having formed inside the solar system.

Investigates the birth of the Solar System. Experiments on the selection of meteorites; Calculation of core-formation ages based on isotope data; Assumption that millimeter-sized particles of calcium and aluminum silicates found inside some meteorites are the oldest objects in the Solar System.

The article reports on the success of the scientists in the U.S. in measuring the oxygen composition at the birth of the Solar System. This discovery accomplishes the top science priority of the National Aeronautics & Space Administration (NASA) Genesis probe which crashed into the Utah desert in 2004. According to Kevin McKeegan, a cosmochemist at the University of California, despite crashing, all the major objectives of Genesis will be met. The finding that the Sun is richer in oxygen-16 than the Earth contradicts the common knowledge that Earth has the same oxygen isotope composition as the Sun. The discovery also provides researchers a reference point for the oxygen composition at the origin of the Solar System.

The article provides information on the composition of isotopes. Isotopes are made through a decay of radioactive nuclei which provide an evidence of how the Earth was shaped. Based on the report made by Boyet and Carlson in the Earth and Planetary Science Letters, showed some clues by measuring the abundance of neodymium isotopes in volcanic rocks. Most of these short-lived elements were produced in the events which is followed by the formation of the Solar System.