Jump to content

List of unsolved problems in astronomy

From Wikipedia, the free encyclopedia

This article is a list of notable unsolved problems in astronomy. Problems may be theoretical or experimental. Theoretical problems result from inability of current theories to explain observed phenomena or experimental results. Experimental problems result from inability to test or investigate a proposed theory. Other problems involve unique events or occurrences that have not repeated themselves with unclear causes.

Planetary astronomy

[edit]

Our solar system

[edit]

Extra-solar

[edit]

Stellar astronomy and astrophysics

[edit]
  • Solar cycle:
    • How does the Sun generate its periodically reversing large-scale magnetic field?
    • How do other Sol-like stars generate their magnetic fields, and what are the similarities and differences between stellar activity cycles and that of the Sun?[6]
    • What caused the Maunder Minimum and other grand minima, and how does the solar cycle recover from a minimum state?
  • Coronal heating problem:
    • Why is the Sun's corona so much hotter than the Sun's surface?
    • Why is the magnetic reconnection effect many orders of magnitude faster than predicted by standard models?
  • Space weather prediction:
  • What is the origin of the stellar mass spectrum? That is, why do astronomers observe the same distribution of stellar masses—the initial mass function—apparently regardless of the initial conditions?[8]
  • Supernova: What is the mechanism by which an implosion of a dying star becomes an explosion?
  • p-nuclei: What astrophysical process is responsible for the nucleogenesis of these rare isotopes?
  • Fast radio bursts (FRBs): What causes these transient radio pulses from distant galaxies, lasting a few milliseconds each? Why do some FRBs repeat at unpredictable intervals but many others do not? Several models have been proposed but no one theory has become widely accepted.[9]
  • The Oh-My-God particle and other ultra-high-energy cosmic rays: What physical processes create cosmic rays whose energy exceeds the GZK cutoff?[10]
  • Nature of KIC 8462852, commonly known as Tabby's Star: What is the origin of the unusual luminosity changes of this star?

Galactic astronomy and astrophysics

[edit]
Rotation curve of a typical spiral galaxy: predicted (A) and observed (B). Can the discrepancy between the curves be attributed to dark matter?
  • Galaxy rotation problem: Is dark matter (solely) responsible for differences in observed and theoretical speed of stars revolving around the center of galaxies?
  • Age-metallicity relation in the Galactic disk: Is there a universal age-metallicity relation (AMR) in the Galactic disk (both "thin" and "thick" parts of the disk)? In the local (primarily thin) disk of the Milky Way, there appears to be no evidence of a strong AMR.[11] A sample of 229 nearby "thick" disk stars has been used to investigate the existence of an age-metallicity relation in the Galactic thick disk and indicates that there is an age-metallicity relation present in the thick disk.[12][13] Stellar ages from asteroseismology confirm the lack of any strong age-metallicity relation in the Galactic disc.[14]
  • Ultraluminous X-ray sources (ULXs): What powers X-ray sources that are not associated with active galactic nuclei but exceed the Eddington limit of a neutron star or stellar black hole? Are they due to intermediate-mass black holes? Some ULXs are periodic, suggesting non-isotropic emission from a neutron star. Does this apply to all ULXs? How could such a system form and remain stable?
  • What is the origin of the Galactic Center GeV excess?[15] Is it due to the annihilation of dark matter particles or a new population of millisecond pulsars?
  • The infrared/TeV crisis: Lack of attenuation of very energetic gamma rays from extragalactic sources.[16][17][18]

Black holes

[edit]

Cosmology

[edit]
Estimated distribution of dark matter and dark energy in the universe

Extraterrestrial life

[edit]
  • Is there other life in the Universe? Especially:
    • Is there other intelligent life?
    • Is there potentially an infinite amount of extraterrestrial genera throughout our universe? If so, what is the explanation for the Fermi paradox?[36][37]
  • Nature of Wow! signal:
    • Was this singular event a result of any extraterrestrial phenomenon? If so, what was its origin?[38]

See also

[edit]

References

[edit]
  1. ^ See Planets beyond Neptune#Orbits of distant objects for details.
  2. ^ "Scientists Find That Saturn's Rotation Period is a Puzzle". NASA. June 28, 2004. Retrieved 2007-03-22.
  3. ^ "/moons/saturn-moons/iapetus". NASA. December 19, 2019. Retrieved 2020-09-07.
  4. ^ "/2015-07-ridge-iapetus". Phys.org. July 21, 2015. Retrieved 2020-09-07.
  5. ^ "how-weird-is-our-solar-system". BBC. May 14, 2015. Retrieved 2020-09-07.
  6. ^ Michael J. Thompson (2014). "Grand Challenges in the Physics of the Sun and Sun-like Stars". Frontiers in Astronomy and Space Sciences. 1: 1. arXiv:1406.4228. Bibcode:2014FrASS...1....1T. doi:10.3389/fspas.2014.00001. S2CID 1547625.
  7. ^ Vourlidas, A.; Patsourakos, S.; Savani, N.P. (2019). "Predicting the geoeffective properties of coronal mass ejections: current status, open issues and path forward". Philosophical Transactions A. 377 (2148). Bibcode:2019RSPTA.37780096V. doi:10.1098/rsta.2018.0096. PMC 6527953. PMID 31079585.
  8. ^ Kroupa, Pavel (2002). "The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems". Science. 295 (5552): 82–91. arXiv:astro-ph/0201098. Bibcode:2002Sci...295...82K. doi:10.1126/science.1067524. PMID 11778039. S2CID 14084249.
  9. ^ Platts, E.; Weltman, A.; Walters, A.; Tendulkar, S.P.; Gordin, J.E.B.; Kandhai, S. (2019). "A living theory catalogue for fast radio bursts". Physics Reports. 821: 1–27. arXiv:1810.05836. Bibcode:2019PhR...821....1P. doi:10.1016/j.physrep.2019.06.003. S2CID 119091423.
  10. ^ Wolchover, Natalie (2015-05-14). "The Particle That Broke a Cosmic Speed Limit". Quanta Magazine. Retrieved 2018-05-04.
  11. ^ Casagrande, L.; Schönrich, R.; Asplund, M.; Cassisi, S.; Ramírez, I.; Meléndez, J.; Bensby, T.; Feltzing, S. (2011). "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s)". Astronomy & Astrophysics. 530: A138. arXiv:1103.4651. Bibcode:2011A&A...530A.138C. doi:10.1051/0004-6361/201016276. S2CID 56118016.
  12. ^ Bensby, T.; Feltzing, S.; Lundström, I. (July 2004). "A possible age-metallicity relation in the Galactic thick disk?". Astronomy and Astrophysics. 421 (3): 969–976. arXiv:astro-ph/0403591. Bibcode:2004A&A...421..969B. doi:10.1051/0004-6361:20035957. S2CID 10469794.
  13. ^ Gilmore, G.; Asiri, H. M. (2011). "Open Issues in the Evolution of the Galactic Disks". Stellar Clusters & Associations: A RIA Workshop on Gaia. Proceedings. Granada: 280. Bibcode:2011sca..conf..280G.
  14. ^ Casagrande, L.; Silva Aguirre, V.; Schlesinger, K. J.; Stello, D.; Huber, D.; Serenelli, A. M.; Scho Nrich, R.; Cassisi, S.; Pietrinferni, A.; Hodgkin, S.; Milone, A. P.; Feltzing, S.; Asplund, M. (2015). "Measuring the vertical age structure of the Galactic disc using asteroseismology and SAGA". Monthly Notices of the Royal Astronomical Society. 455 (1): 987–1007. arXiv:1510.01376. Bibcode:2016MNRAS.455..987C. doi:10.1093/mnras/stv2320. S2CID 119113283.
  15. ^ Hooper, Dan & Goodenough, Lisa (21 March 2011). "Dark matter annihilation in the Galactic Center as seen by the Fermi Gamma Ray Space Telescope". Physics Letters B. 697 (5): 412–428. arXiv:1010.2752. Bibcode:2011PhLB..697..412H. doi:10.1016/j.physletb.2011.02.029. S2CID 118446838.
  16. ^ Troitsky, Sergey (2021). "The local-filament pattern in the anomalous transparency of the Universe for energetic gamma rays". The European Physical Journal C. 81 (3): 264. arXiv:2004.08321. Bibcode:2021EPJC...81..264T. doi:10.1140/epjc/s10052-021-09051-6. S2CID 215814512.
  17. ^ Protheroe, R.J.; Meyer, H. (2000). "An infrared background-TeV gamma-ray crisis?". Physics Letters B. 493 (1–2): 1–6. arXiv:astro-ph/0005349. Bibcode:2000PhLB..493....1P. doi:10.1016/S0370-2693(00)01113-8. S2CID 1436019.
  18. ^ Aharonian, Felix A (2004). Very High Energy Cosmic Gamma Radiation: A Crucial Window On The Extreme Universe. World Scientific Publishing Co. p. 432. ISBN 981-02-4573-4. Retrieved 21 April 2020.
  19. ^ Ferrarese, Laura; Merritt, David (2000). "A Fundamental Relation between Supermassive Black Holes and their Host Galaxies". The Astrophysical Journal. 539 (1): L9–L12. arXiv:astro-ph/0006053. Bibcode:2000ApJ...539L...9F. doi:10.1086/312838. S2CID 6508110.
  20. ^ Peres, Asher; Terno, Daniel R. (2004). "Quantum information and relativity theory". Reviews of Modern Physics. 76 (1): 93–123. arXiv:quant-ph/0212023. Bibcode:2004RvMP...76...93P. doi:10.1103/revmodphys.76.93. S2CID 7481797.
  21. ^ Ouellette, Jennifer (21 December 2012). "Black Hole Firewalls Confound Theoretical Physicists". Scientific American. Archived from the original on 9 November 2013. Retrieved 29 October 2013. Originally published Archived 3 June 2014 at the Wayback Machine in Quanta, December 21, 2012.
  22. ^ D'Orazio, Daniel J.; Haiman, Zoltán; Schiminovich, David (17 September 2015). "Relativistic boost as the cause of periodicity in a massive black-hole binary candidate". Nature. 525 (7569): 351–353. arXiv:1509.04301. Bibcode:2015Natur.525..351D. doi:10.1038/nature15262. PMID 26381982. S2CID 205245606.
  23. ^ Milosavljević, Miloš; Merritt, David (October 2003). "The Final Parsec Problem" (PDF). AIP Conference Proceedings. 686 (1). American Institute of Physics: 201–210. arXiv:astro-ph/0212270. Bibcode:2003AIPC..686..201M. doi:10.1063/1.1629432. S2CID 12124842.
  24. ^ a b c d e Abdalla, Elcio; Abellán, Guillermo Franco; Aboubrahim, Armin (11 Mar 2022), "Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies", Journal of High Energy Astrophysics, 34: 49, arXiv:2203.06142v1, Bibcode:2022JHEAp..34...49A, doi:10.1016/j.jheap.2022.04.002, S2CID 247411131
  25. ^ Billings, Lee (April 15, 2020). "Do We Live in a Lopsided Universe?". Scientific American. Retrieved March 24, 2022.
  26. ^ Migkas, K.; Schellenberger, G.; Reiprich, T. H.; Pacaud, F.; Ramos-Ceja, M. E.; Lovisari, L. (8 April 2020). "Probing cosmic isotropy with a new X-ray galaxy cluster sample through the LX-T scaling relation". Astronomy & Astrophysics. 636 (April 2020): 42. arXiv:2004.03305. Bibcode:2020A&A...636A..15M. doi:10.1051/0004-6361/201936602. S2CID 215238834. Retrieved 24 March 2022.
  27. ^ Krishnan, Chethan; Mohayaee, Roya; Colgáin, Eoin Ó; Sheikh-Jabbari, M. M.; Yin, Lu (16 September 2021). "Does Hubble Tension Signal a Breakdown in FLRW Cosmology?". Classical and Quantum Gravity. 38 (18): 184001. arXiv:2105.09790. Bibcode:2021CQGra..38r4001K. doi:10.1088/1361-6382/ac1a81. ISSN 0264-9381. S2CID 234790314.
  28. ^ a b Ellis, G. F. R. (2009). "Dark energy and inhomogeneity". Journal of Physics: Conference Series. 189 (1): 012011. Bibcode:2009JPhCS.189a2011E. doi:10.1088/1742-6596/189/1/012011. S2CID 250670331.
  29. ^ a b Colin, Jacques; Mohayaee, Roya; Rameez, Mohamed; Sarkar, Subir (20 November 2019). "Evidence for anisotropy of cosmic acceleration". Astronomy and Astrophysics. 631: L13. arXiv:1808.04597. Bibcode:2019A&A...631L..13C. doi:10.1051/0004-6361/201936373. S2CID 208175643. Retrieved 25 March 2022.
  30. ^ a b Brooks, Michael (March 19, 2005). "13 Things That Do Not Make Sense". New Scientist. Issue 2491. Retrieved March 7, 2011.
  31. ^ Poulin, Vivian; Smith, Tristan L.; Karwal, Tanvi; Kamionkowski, Marc (2019-06-04). "Early Dark Energy can Resolve the Hubble Tension". Physical Review Letters. 122 (22): 221301. arXiv:1811.04083. Bibcode:2019PhRvL.122v1301P. doi:10.1103/PhysRevLett.122.221301. PMID 31283280. S2CID 119233243. |
  32. ^ Steinhardt, P. & Turok, N. (2006). "Why the Cosmological constant is so small and positive". Science. 312 (5777): 1180–1183. arXiv:astro-ph/0605173. Bibcode:2006Sci...312.1180S. doi:10.1126/science.1126231. PMID 16675662. S2CID 14178620.
  33. ^ Wang, Qingdi; Zhu, Zhen; Unruh, William G. (2017-05-11). "How the huge energy of quantum vacuum gravitates to drive the slow accelerating expansion of the Universe". Physical Review D. 95 (10): 103504. arXiv:1703.00543. Bibcode:2017PhRvD..95j3504W. doi:10.1103/PhysRevD.95.103504. S2CID 119076077. This problem is widely regarded as one of the major obstacles to further progress in fundamental physics [...] Its importance has been emphasized by various authors from different aspects. For example, it has been described as a "veritable crisis" [...] and even "the mother of all physics problems" [...] While it might be possible that people working on a particular problem tend to emphasize or even exaggerate its importance, those authors all agree that this is a problem that needs to be solved, although there is little agreement on what is the right direction to find the solution.
  34. ^ Podolsky, Dmitry. "Top ten open problems in physics". NEQNET. Archived from the original on 22 October 2012. Retrieved 24 January 2013.
  35. ^ Wolchover, Natalie (2019). "Cosmologists Debate How Fast the Universe Is Expanding". Quanta Magazine. Retrieved 24 February 2020.
  36. ^ "Rare Earth: Complex Life Elsewhere in the Universe?". Astrobiology Magazine. 15 July 2002. Archived from the original on 28 June 2011. Retrieved 12 August 2006.
  37. ^ Sagan, Carl. "The Quest for Extraterrestrial Intelligence". Cosmic Search Magazine. Archived from the original on 18 August 2006. Retrieved 12 August 2006.
  38. ^ Kiger, Patrick J. (2012-06-21). "What is the Wow! signal?". National Geographic Channel. Archived from the original on March 13, 2015. Retrieved 2016-07-02.