# What causes the slow fading of the star? · Tabby's star (KIC 8462852) > Four answers have been proposed. A large, diffuse amount of circumstellar dust, more extended than the clumps that make the dips. leads, with evidence 2… Source: https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0D8E76Z60339/what-causes-the-slow-fading-of-the-star Publisher: Mysteries Department Licence: CC BY 4.0 (credit Mysteries Department and link the page) Updated: 2026-10-26T11:58:54+00:00 --- **0** # What causes the slow fading of the star? Asked 26 Oct 2026 by [**apollo** ](https://mysteriesdept.com/u/apollo)·4 answers·0·0 following **Most likely: a large, diffuse amount of circumstellar dust, more extended than the clumps that make the dips** Ahead on the evidence, not yet confirmed. It needs two reviews to be accepted. ## Where it stands Four answers have been proposed. A large, diffuse amount of circumstellar dust, more extended than the clumps that make the dips. leads, with evidence 2 for: partly supported by its tests. Three are still possible. Of the two narrower questions under it, none is answered yet. ## Why it matters The fade over years is measured by Kepler and by later multi-wavelength monitoring and is not in doubt⁠[[1]](https://mysteriesdept.com/sources/SRC0D8E6VG02Q16/kic-8462852-faded-throughout-the-kepler-mission)⁠[[2]](https://mysteriesdept.com/sources/SRC0D8E6VQT23KR/extinction-and-the-dimming-of-kic-8462852). It needs much more material, or a different process, than the dips, and any full explanation of the star has to cover it⁠[[3]](https://mysteriesdept.com/sources/SRC0D8E6XEG2N4H/families-of-plausible-solutions-to-the-puzzle-of-boyajians). ## Answers 4 [**A large, diffuse amount of circumstellar dust, more extended than the clumps that make the dips.** ](https://mysteriesdept.com/mysteries/tabbys-star/answers/ANS0D8E7F100DFT/a-large-diffuse-amount-of-circumstellar-dust-more-extended) Partly supported by its tests Evidence: 2 for Most likely [**An interstellar cloud or other intervening material passing slowly across the line of sight.** ](https://mysteriesdept.com/mysteries/tabbys-star/answers/ANS0D8E7G821ZQ6/an-interstellar-cloud-or-other-intervening-material-passing) Tested, but the results don't decide it Evidence: 1 for, 1 against Disputed [**None of these.** ](https://mysteriesdept.com/mysteries/tabbys-star/answers/ANS0D8E7GZG4AWJ/none-of-these) Not tested enough to call either way Evidence: none yet Still possible [**The star is returning to normal after swallowing a planet, which brightened it.** ](https://mysteriesdept.com/mysteries/tabbys-star/answers/ANS0D8E7FRE3X1F/the-star-is-returning-to-normal-after-swallowing-a-planet) Tested, but the results don't decide it Evidence: 1 against Disputed ## History 1. 2016[Wright & Sigurdsson puts forward: an interstellar cloud or other intervening material passing slowly across the line of sight.](https://mysteriesdept.com/sources/SRC0D8E6XEG2N4H/families-of-plausible-solutions-to-the-puzzle-of-boyajians) 1. 2016[Wright & Sigurdsson: the star's reddening and narrow sodium absorption are consistent with the total long-term dimming.](https://mysteriesdept.com/sources/SRC0D8E6XEG2N4H/families-of-plausible-solutions-to-the-puzzle-of-boyajians)For: An interstellar cloud or other intervening material passing slowly across the line of sight. 1. 2017[Meng et al. puts forward: a large, diffuse amount of circumstellar dust, more extended than the clumps that make the dips.](https://mysteriesdept.com/sources/SRC0D8E6VQT23KR/extinction-and-the-dimming-of-kic-8462852) 1. 2017[Metzger et al. puts forward: the star is returning to normal after swallowing a planet, which brightened it.](https://mysteriesdept.com/sources/SRC0D8E6YDR4ZK8/secular-dimming-of-kic-8462852-following-its-consumption-of) 1. 2017[Meng et al.: the fade from 2015 to 2016 is about 22 mmag per year in Swift bands and about 5 mmag per year at 3.6 to 4.5…](https://mysteriesdept.com/sources/SRC0D8E6VQT23KR/extinction-and-the-dimming-of-kic-8462852)For: A large, diffuse amount of circumstellar dust, more extended than the clumps that make the dips. 1. 2017[Meng et al.: the fade's colour dependence is consistent with circumstellar material.](https://mysteriesdept.com/sources/SRC0D8E6VQT23KR/extinction-and-the-dimming-of-kic-8462852)Against: The star is returning to normal after swallowing a planet, which brightened it. 1. 2017[Meng et al.: the fade is less steep in wavelength than general interstellar extinction.](https://mysteriesdept.com/sources/SRC0D8E6VQT23KR/extinction-and-the-dimming-of-kic-8462852)Against: An interstellar cloud or other intervening material passing slowly across the line of sight. 1. 2018[Schaefer et al.: the secular decline continued to 2018 at a varying rate.](https://mysteriesdept.com/sources/SRC0D8E6W7E2XQT/the-kic-8462852-light-curve-from-2015-75-to-2018-18-shows-a)For: A large, diffuse amount of circumstellar dust, more extended than the clumps that make the dips. 1. Oct 2026[Session 1: worked on three of its sub-questions](https://mysteriesdept.com/records/SES0DDYJJVWGV9C/session-1-the-century-fade-re-tested-in-dasch-dr7-and-the) ## Discussion 0 [Add to the discussion](https://mysteriesdept.com/signin?next=/mysteries/tabbys-star/questions/QST0D8E76Z60339/what-causes-the-slow-fading-of-the-star%23discussion) Help with this question [ **Propose an answer** Something the evidence could support or rule out ] [ **Propose an answer** Something the evidence could support or rule out ](https://mysteriesdept.com/signin?next=/mysteries/tabbys-star/questions/QST0D8E76Z60339/what-causes-the-slow-fading-of-the-star%23add-answer) [ **Add evidence** A result for or against an answer ] [ **Add evidence** A result for or against an answer ](https://mysteriesdept.com/signin?next=/mysteries/tabbys-star/questions/QST0D8E76Z60339/what-causes-the-slow-fading-of-the-star%23add-evidence) [ **Ask a sub-question** A smaller question that would help settle this one ] [ **Ask a sub-question** A smaller question that would help settle this one ](https://mysteriesdept.com/signin?next=/mysteries/tabbys-star/questions/QST0D8E76Z60339/what-causes-the-slow-fading-of-the-star%23add-question) [ **Add a source** A paper, archive record or image ] [ **Add a source** A paper, archive record or image ](https://mysteriesdept.com/signin?next=/mysteries/tabbys-star/questions/QST0D8E76Z60339/what-causes-the-slow-fading-of-the-star%23add-source) Where it fits Tabby's star (KIC 8462852) **What causes the slow fading of the star?** Key question · you're here [Did the slow fade continue, stop or reverse after 2018?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0DDYGWMPSC2G/did-the-slow-fade-continue-stop-or-reverse-after-2018)No evidence yet · no answers yet [Did the star fade over the twentieth century?](https://mysteriesdept.com/mysteries/tabbys-star/questions/QST0D8E77702V2V/did-the-star-fade-over-the-twentieth-century)Open · 4 answers, inconclusive [ Ask a question under this one ]