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ABSTRACT Our Solar System was formed from a cloud of gas and dust. Most of the dust mass is contained in amorphous silicates1, yet crystalline silicates are abundant throughout the Solar

System, reflecting the thermal and chemical alteration of solids during planet formation. (Even primitive bodies such as comets contain crystalline silicates2.) Little is known about the

evolution of the dust that forms Earth-like planets. Here we report spatially resolved detections and compositional analyses of these building blocks in the innermost two astronomical units

of three proto-planetary disks. We find the dust in these regions to be highly crystallized, more so than any other dust observed in young stars until now. In addition, the outer region of

one star has equal amounts of pyroxene and olivine, whereas the inner regions are dominated by olivine. The spectral shape of the inner-disk spectra shows surprising similarity with Solar

System comets. Radial-mixing models naturally explain this resemblance as well as the gradient in chemical composition. Our observations imply that silicates crystallize before any

terrestrial planets are formed, consistent with the composition of meteorites in the Solar System. Access through your institution Buy or subscribe This is a preview of subscription content,

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OPTIONS: * Log in * Learn about institutional subscriptions * Read our FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS DUST FROM SUPERNOVAE AND THEIR PROGENITORS IN

THE SOLAR NEBULA Article 01 August 2022 THE COSMOCHEMISTRY OF PLANETARY SYSTEMS Article 28 April 2025 UV-DRIVEN CHEMISTRY AS A SIGNPOST OF LATE-STAGE PLANET FORMATION Article 08 December

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based on observations obtained at the European Southern Observatory (ESO), Chile. We thank all those involved in building VLTI and MIDI. We thank V. Icke for providing the illustration shown

in Fig. 2. C.P. Dullemond is acknowledged for many discussions. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Astronomical Institute “Anton Pannekoek”, University of Amsterdam, Kruislaan

403, 1098 SJ, Amsterdam, The Netherlands R. van Boekel, M. Min, L.B.F.M. Waters, C. Dominik & A. de Koter * European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748,

Garching, Germany R. van Boekel, A. Richichi, S. Morel, F. Paresce, M. Schöller & M. Wittkowski * Max-Planck-Institut für Astronomie Heidelberg, Königstuhl 17, 69117, Heidelberg, Germany

Ch. Leinert, O. Chesneau, U. Graser, Th. Henning, R. Köhler & F. Przygodda * Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200B, 3001, Heverlee, Belgium L.B.F.M. Waters *

Leiden Observatory, Niels Bohrweg 2, 2333 CA, Leiden, The Netherlands W. Jaffe & J. de Jong * Observatoire de Bordeaux, 2, rue de l'Observatoire, F-33270, Floirac, France A. Dutrey 

& F. Malbet * Observatoire de la Côte d'Azur, Département Fresnel UMR 6528, BP 4229, 06034, Nice, Cedex 4, France B. Lopez * Laboratoire d'Etudes Spatiales et

d'Instrumentation en Astrophysique, Observatoire de Paris, section de Meudon, 5 place Jule Janssen, 92190, Meudon, France G. Perrin * Max-Planck-Institut für Radioastronomie, Auf dem

Hügel 69, 53121, Bonn, Germany Th. Preibisch Authors * R. van Boekel View author publications You can also search for this author inPubMed Google Scholar * M. Min View author publications

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author publications You can also search for this author inPubMed Google Scholar * C. Dominik View author publications You can also search for this author inPubMed Google Scholar * W. Jaffe

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Graser View author publications You can also search for this author inPubMed Google Scholar * Th. Henning View author publications You can also search for this author inPubMed Google Scholar

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can also search for this author inPubMed Google Scholar CORRESPONDING AUTHOR Correspondence to R. van Boekel. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare that they have no

competing financial interests. SUPPLEMENTARY INFORMATION SUPPLEMENTARY INFORMATION Contains a more detailed discussion of our data analysis and error estimation: Fitting procedure, error

analysis, Supplementary Figure 1 and references. (PDF 97 kb) RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE van Boekel, R., Min, M., Leinert, C. _et

al._ The building blocks of planets within the ‘terrestrial’ region of protoplanetary disks. _Nature_ 432, 479–482 (2004). https://doi.org/10.1038/nature03088 Download citation * Received:

05 May 2004 * Accepted: 05 October 2004 * Issue Date: 25 November 2004 * DOI: https://doi.org/10.1038/nature03088 SHARE THIS ARTICLE Anyone you share the following link with will be able to

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