Hypothetical astronomical object
Artist's concept of Earth, orbited by a hypothetical second moon.
Artist's concept of a carbon planet. The surface is dark and reddish from hydrocarbon deposits.
Various unknown astronomical objects have been hypothesized throughout recorded history. For example, in the 5th century BCE, the philosopher Philolaus defined a hypothetical astronomical object which he called the "Central Fire", around which he proposed other celestial bodies (including the Sun) moved.[1]
Types of hypothetical astronomical objects[]
Hypothetical astronomical objects have been speculated to exist both inside and outside of the Solar System, and speculation has included different kinds of stars, planets, and other astronomical objects.
- For hypothetical astronomical objects in the Solar System, see: List of hypothetical Solar System objects
- For hypothetical stars, see Hypothetical star
- For hypothetical brown dwarfs, see: List of brown dwarfs
- For hypothetical black holes, see: Hypothetical black hole
- For extrasolar moons, all of which are currently hypothetical, see: Extrasolar moon
- For stars, planets or moons whose existence is not accepted by science see: Planetary objects proposed in religion, astrology, ufology and pseudoscience and Stars proposed in religion
- For hypothetical planets in fiction see: Fictional planets of the Solar System
Hypothetical planet types[]
Hypothetical types of extrasolar planet include:
- Blanet: A planet in orbit around a black hole.
- Carbon planet: A terrestrial planet composed primarily of carbon, rather than silicon.
- Chthonian planet: A hot Jupiter whose outer layers have been completely stripped off by its parent star.
- Coreless planet: A terrestrial planet that has no metallic core.
- Desert planet: A terrestrial planet with little to no water.
- Eyeball planet: A terrestrial planet tidally locked, for which tidal locking induces spatial features resembling an eye-like central region (e.g. a planet covered in ice or deserts save for a small temperate patch).
- Helium planet: A gas giant planet formed around a white dwarf star that is composed mainly of helium instead of hydrogen.
- Hycean planet /ˈhaɪʃən/: A hot, water-covered planet with a hydrogen-rich atmosphere that is possibly capable of harboring life.[2][3][4]
- Iron planet, A planet like Mercury that consists mainly of an iron core with little mantle.
- Ocean planet: A planet whose surface is covered entirely by deep oceans.
- Superhabitable planet: a terrestrial planet more habitable than Earth.
- Tidally detached exomoon: A planet that was originally a moon but has become gravitationally detached. Similarly, Pluto was once thought to be an escaped satellite of Neptune.
- Trojan planet: A planet that orbits with a star instead of around it.
References[]
- ^ Marco Ceccarelli, Distinguished Figures in Mechanism and Machine Science (2007), p. 124.
- ^ Madhusudhan, Nikku; Piette, Anjali a. A.; Constantinou, Savvas (26 August 2021). "Habitability and Biosignatures of Hycean Worlds". The Astrophysical Journal. 918 (1): 1. arXiv:2108.10888. Bibcode:2021ApJ...918....1M. doi:10.3847/1538-4357/abfd9c. S2CID 237290118. Retrieved 12 December 2021.
- ^ Anderson, Paul Scott (29 August 2021). "Hycean planets might be habitable ocean worlds". Earth & Sky. Retrieved 12 December 2021.
- ^ Davis, Nicola (25 August 2021). "'Mini-Neptunes' beyond solar system may soon yield signs of life - Cambridge astronomers identify new hycean class of habitable exoplanets, which could accelerate search for life". The Guardian. Retrieved 12 December 2021.
Categories:
- Astronomy
- Hypothetical astronomical objects