Dawniej uznawano istnienie większej ilości planet, np. uznawano Plutona za planetę oraz wierzono w istnienie innych (hipotetycznych) planet Układu Słonecznego. Te tezy nie znajdują poparcia we współczesnej nauce.
W styczniu 2016 roku opublikowano pracę, która wykazuje duże prawdopodobieństwo istnienia dziewiątej planety o masie rzędu 10 mas Ziemi poza orbitą Neptuna. Hipoteza ta nie została potwierdzona; nie zaobserwowano takiego obiektu. (Zob. Konstantin Batygin, Michael E. Brown: Evidence for a Distant Giant Planet in the Solar System. 20 stycznia 2016. (ang.).).
AlessandroA.MorbidelliAlessandroA., Origin and Dynamical Evolution of Comets and their Reservoirs, „arXiv [astro-ph]”, CNRS, Observatoire de la Côte d’Azur, 2006, DOI: 10.48550/arXiv.astro-ph/0512256, arXiv:astro-ph/0512256v1 [dostęp 2007-08-03].
Charles H. Lineweaver. An Estimate of the Age Distribution of Terrestrial Planets in the Universe: Quantifying Metallicity as a Selection Effect. „arXiv + Icarus”. 151 (2), s. 307–313, 2001-03-09. University of New South Wales. DOI: 10.1006/icar.2001.6607. arXiv:astro-ph/0012399.
M.W. Buie, R.L. Millis, L.H. Wasserman, J.L. Elliot, S.D. Kern, K.B. Clancy, E.I. Chiang, A.B. Jordan, K.J. Meech, R.M. Wagner, D.E. Trilling. Procedures, Resources and Selected Results of the Deep Ecliptic Survey. „arXiv + Earth, Moon, and Planets”. 92 (1–4), s. 113–124, June 2003. Lowell Observatory, University of Pennsylvania, Large Binocular Telescope Observatory, Massachusetts Institute of Technology, University of Hawaii, University of California at Berkeley. DOI: 10.1023/B:MOON.0000031930.13823.be. arXiv:astro-ph/0309251.
A.D. Dolgov. Magnetic fields in cosmology. „arXiv + talk presented at 17th Rencontre de Physique de la Vallee d'Aoste on Results and Perspectives in Particle Physics, March 9-15, 2003”, 2003. arXiv:astro-ph/0306443.
R. Drimmel, D. N. Spergel. Three Dimensional Structure of the Milky Way Disk. „The Astrophysical Journal”. 556 (1), s. 181, 2001. DOI: 10.1086/321556. arXiv:astro-ph/0101259.
J.F. Kasting, T.P. Ackerman. Climatic Consequences of Very High Carbon Dioxide Levels in the Earth’s Early Atmosphere. „Science”. 234, s. 1383–1385, 1986. DOI: 10.1126/science.11539665. PMID: 11539665.
T.S. van Albada, Norman Baker. On the Two Oosterhoff Groups of Globular Clusters. „Astrophysical Journal”. 185, s. 477–498, 1973. DOI: 10.1086/152434.
Charles H. Lineweaver. An Estimate of the Age Distribution of Terrestrial Planets in the Universe: Quantifying Metallicity as a Selection Effect. „arXiv + Icarus”. 151 (2), s. 307–313, 2001-03-09. University of New South Wales. DOI: 10.1006/icar.2001.6607. arXiv:astro-ph/0012399.
U.W. Langner, M.S. Potgieter. Effects of the position of the solar wind termination shock and the heliopause on the heliospheric modulation of cosmic rays. „Advances in Space Research”. 35 (12), s. 2084–2090, 2005. DOI: 10.1016/j.asr.2004.12.005. Bibcode: 2005AdSpR..35.2084L.
Podolak, M.; Reynolds, R.T.; Young, R. Post Voyager comparisons of the interiors of Uranus and Neptune. „Geophysical Research Letters”. 17 (10), s. NASA, Ames Research Center, 1990. DOI: 10.1029/GL017i010p01737. Bibcode: 1990GeoRL..17.1737P.
J. Fajans, L. Frièdland. Autoresonant (nonstationary) excitation of pendulums, Plutinos, plasmas, and other nonlinear oscillators. „American Journal of Physics”. 69 (10), s. 1096–1102, październik 2001. DOI: 10.1119/1.1389278. (ang.).
M.W. Buie, R.L. Millis, L.H. Wasserman, J.L. Elliot, S.D. Kern, K.B. Clancy, E.I. Chiang, A.B. Jordan, K.J. Meech, R.M. Wagner, D.E. Trilling. Procedures, Resources and Selected Results of the Deep Ecliptic Survey. „arXiv + Earth, Moon, and Planets”. 92 (1–4), s. 113–124, June 2003. Lowell Observatory, University of Pennsylvania, Large Binocular Telescope Observatory, Massachusetts Institute of Technology, University of Hawaii, University of California at Berkeley. DOI: 10.1023/B:MOON.0000031930.13823.be. arXiv:astro-ph/0309251.
Stern S.A., Weissman P.R. Rapid collisional evolution of comets during the formation of the Oort cloud. „Nature”. 409 (6820), s. 589–91, Feb 2001. Boulder, Colorado: Space Studies Department, Southwest Research Institute. DOI: 10.1038/35054508. PMID: 11214311.
R. Drimmel, D. N. Spergel. Three Dimensional Structure of the Milky Way Disk. „The Astrophysical Journal”. 556 (1), s. 181, 2001. DOI: 10.1086/321556. arXiv:astro-ph/0101259.
AlessandroA.MorbidelliAlessandroA., Origin and Dynamical Evolution of Comets and their Reservoirs, „arXiv [astro-ph]”, CNRS, Observatoire de la Côte d’Azur, 2006, DOI: 10.48550/arXiv.astro-ph/0512256, arXiv:astro-ph/0512256v1 [dostęp 2007-08-03].
R.L.R.L.SmartR.L.R.L. i inni, The Second Guide Star Catalogue and Cool Stars, „Ultracool Dwarfs: New Spectral Types L and T.”, Springer, 2001, s. 119, Bibcode: 2001udns.conf..119S [dostęp 2006-12-26].
U.W. Langner, M.S. Potgieter. Effects of the position of the solar wind termination shock and the heliopause on the heliospheric modulation of cosmic rays. „Advances in Space Research”. 35 (12), s. 2084–2090, 2005. DOI: 10.1016/j.asr.2004.12.005. Bibcode: 2005AdSpR..35.2084L.
Beech, M., Duncan I. Steel. On the Definition of the Term Meteoroid. „Quarterly Journal of the Royal Astronomical Society”. 36 (3), s. 281–284, wrzesień 1995. Bibcode: 1995QJRAS..36..281B.
Hawksett, David; Longstaff, Alan; Cooper, Keith; Clark, Stuart. 10 Mysteries of the Solar System. „Astronomy Now”. 19 (8), s. 65–75, 2005. ISSN0951-9726. Bibcode: 2005AsNow..19h..65H.
Podolak, M.; Reynolds, R.T.; Young, R. Post Voyager comparisons of the interiors of Uranus and Neptune. „Geophysical Research Letters”. 17 (10), s. NASA, Ames Research Center, 1990. DOI: 10.1029/GL017i010p01737. Bibcode: 1990GeoRL..17.1737P.
Fahr, H.J.; Kausch, T.; Scherer, H. A 5-fluid hydrodynamic approach to model the Solar System-interstellar medium interaction. „Astronomy and Astrophysics”. 357, s. 268–282, 2000. Institut für Astrophysik und Extraterrestrische Forschung der Universität Bonn. Bibcode: 2000A&A...357..268F.
J.F. Kasting, T.P. Ackerman. Climatic Consequences of Very High Carbon Dioxide Levels in the Earth’s Early Atmosphere. „Science”. 234, s. 1383–1385, 1986. DOI: 10.1126/science.11539665. PMID: 11539665.
Stern S.A., Weissman P.R. Rapid collisional evolution of comets during the formation of the Oort cloud. „Nature”. 409 (6820), s. 589–91, Feb 2001. Boulder, Colorado: Space Studies Department, Southwest Research Institute. DOI: 10.1038/35054508. PMID: 11214311.
Mark AlanM.A.BullockMark AlanM.A., The Stability of Climate on Venus [PDF], Southwest Research Institute, 1997 [dostęp 2006-12-26] [zarchiwizowane z adresu 2007-06-14]. Brak numerów stron w książce
Mark AlanM.A.BullockMark AlanM.A., The Stability of Climate on Venus [PDF], Southwest Research Institute, 1997 [dostęp 2006-12-26] [zarchiwizowane z adresu 2007-06-14]. Brak numerów stron w książce