John Percy (University of Toronto) tried to answer this question in an article, dated 2020, focused on the evolution of Betelgeuse

Betelgeuse is not new to visible changes in luminosities. This star has a primary pulsation period of 388 ± 30 days and a “long secondary period” of 2025 ± 460 days. Both periods vary in size. At the time of the “Great Dimming” in 2020, both were at their minimum phase and maximum amplitude, resulting in an unusually deep minimum of brightness. Other observations also showed that this minimum was further amplified by a jet of dust along our line of sight.

Betelgeuse location in the Orion constellation. Credit: Akira Fujii

Assuming that these periods and their variations in amplitude continue, then we might expect similar “great dimmings” in the future, which in fact have already occurred in the past, for example in 1925–26. This shows the benefit derived from long-term observations and data, including those gathered from collaborations between amateur and professional astronomers, such as the American Association of Variable Star Observers (AAVSO).


Percy 2020, JRASC, 114, 134

Goldberg 1984, PASP, 96, 366

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