The Infinite ArchiveTHE INFINITE ARCHIVEHISTORY · SCIENCE · MYSTERY
Tabby's Star (KIC 8462852) in infrared and ultraviolet survey images
Tabby's Star (KIC 8462852) in infrared and ultraviolet survey images. Image: Infrared: IPAC/NASA Ultraviolet: STScI (NASA) · Public domain · via Wikimedia Commons
Open cases · Kepler data 2009–2013 · dips through 2019

Tabby's Star: The Flickering Puzzle

Contested2015 CE – 2019 CEKIC 8462852, constellation Cygnus (sky position)

A star that dimmed by up to 22% at random — once nicknamed the 'alien megastructure' star.

Research draft · editor review pending. Every claim below is linked to a checked source, but this dossier has not yet been reviewed by a human editor. Spot an error? Corrections are logged.

In 2015, volunteers with the Planet Hunters project noticed that a star in the Kepler space telescope's data, KIC 8462852, dimmed in bizarre, irregular ways — at one point by about 22% — unlike any planet transit. The discovery paper, led by Tabetha Boyajian, carried the subtitle 'Where's the flux?'

The strangeness prompted proposals ranging from swarms of comets to an artificial 'megastructure,' and the star was searched for radio and laser signals. Observations of later dips in 2017 showed the dimming was deeper in blue light than in red, which points to fine dust rather than a solid object. What produces that dust, and why it is so uneven, is still debated.

Case log

An open case. Dated developments, oldest first, each with its source.

  1. Discovery paper on the star's strange dips posted; published in MNRAS in 2016.

    Sources: 1

  2. A new dip ('Elsie') is caught in real time, triggering worldwide observations.

    Sources: 2

  3. NASA reports the dimming is likely caused by an uneven ring of dust.

    Sources: 3

Why it matters

It shows how a strange signal is narrowed down: test predictions, rule out the exotic, and keep the remaining puzzle honest.

What the evidence says

  1. Established

    Kepler recorded irregular dips in the star's brightness unlike planetary transits.

    Basis: Discovery paper in MNRAS (2016).

    Sources: 1
  2. Established

    The 2017 dips were wavelength-dependent, consistent with fine dust rather than an opaque object.

    Basis: Ground-based monitoring (ApJ Letters, 2018); NASA infrared and ultraviolet study.

    Sources: 23
  3. Contested

    The star also faded gradually during the Kepler mission.

    Basis: Kepler full-frame image analysis (ApJ Letters, 2016).

    Counterpoint: Claims of a century-long fade from old photographic plates were disputed.

    Sources: 45
  4. Established

    A red dwarf companion about 880 AU away was confirmed in 2021.

    Basis: Astrometry (ApJ, 2021).

    Sources: 6
  5. Speculative

    The dips could be caused by an artificial megastructure.

    Basis: Raised as a hypothesis to test (ApJ, 2016).

    Counterpoint: The wavelength-dependent dimming argues against an opaque structure.

    Sources: 7

Competing interpretations

Uneven circumstellar dust

Clouds of fine dust, perhaps from disrupted comets or bodies, pass in front of the star.

Standing: Best supported by multi-color data.
Sources: 3

Comet swarm

A family of comets on an eccentric orbit.

Standing: Proposed early; partly consistent.
Sources: 8

Alien megastructure

Engineered structures blocking starlight.

Standing: Speculative; disfavored by the dust evidence.
Sources: 7

Weigh the evidence

Having read the claims and sources, which explanation do you find most convincing?

One vote per browser. Results appear after you vote.

Open questions

Connected dossiers

The Wow! SignalSame open question · An 'alien' explanation tested and narrowed.The Discovery of PulsarsContrast · A strange signal later explained by nature.

See Tabby's Star in the discovery universe →

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Sources

  1. Boyajian, LaCourse, Rappaport et al.. “Planet Hunters IX. KIC 8462852 – where's the flux?.” Monthly Notices of the Royal Astronomical Society (2016) DOI 10.1093/mnras/stw218
    PEER-REVIEWED · CHECKED 2026-10-22 · CROSSREF DOI METADATA
  2. Boyajian, Alonso, Ammerman et al.. “The First Post- Kepler Brightness Dips of KIC 8462852.” The Astrophysical Journal Letters (2018) DOI 10.3847/2041-8213/aaa405
    PEER-REVIEWED · CHECKED 2026-10-22 · CROSSREF DOI METADATA
  3. Landau, Elizabeth. “Mysterious Dimming of Tabby's Star May Be Caused by Dust.” NASA Jet Propulsion Laboratory (2017) Open source ↗
    INSTITUTION · CHECKED 2026-10-22 · HTTP 200 LINK CHECK
  4. Montet, Simon. “KIC 8462852 FADED THROUGHOUT THE KEPLER MISSION.” The Astrophysical Journal Letters (2016) DOI 10.3847/2041-8205/830/2/L39
    PEER-REVIEWED · CHECKED 2026-10-22 · CROSSREF DOI METADATA
  5. Hippke, Angerhausen, Lund et al.. “A STATISTICAL ANALYSIS OF THE ACCURACY OF THE DIGITIZED MAGNITUDES OF PHOTOMETRIC PLATES ON THE TIMESCALE OF DECADES WITH AN APPLICATION TO THE CENTURY-LONG LIGHT CURVE OF KIC 8462852.” The Astrophysical Journal (2016) DOI 10.3847/0004-637X/825/1/73
    PEER-REVIEWED · CHECKED 2026-10-22 · CROSSREF DOI METADATA
  6. Pearce, Kraus, Dupuy et al.. “Boyajian’s Star B: The Co-moving Companion to KIC 8462852 A.” The Astrophysical Journal (2021) DOI 10.3847/1538-4357/abdd33
    PEER-REVIEWED · CHECKED 2026-10-22 · CROSSREF DOI METADATA
  7. Wright, Cartier, Zhao et al.. “THE Ĝ SEARCH FOR EXTRATERRESTRIAL CIVILIZATIONS WITH LARGE ENERGY SUPPLIES. IV. THE SIGNATURES AND INFORMATION CONTENT OF TRANSITING MEGASTRUCTURES.” The Astrophysical Journal (2015) DOI 10.3847/0004-637X/816/1/17
    PEER-REVIEWED · CHECKED 2026-10-22 · CROSSREF DOI METADATA
  8. “Strange Star Likely Swarmed by Comets.” NASA Jet Propulsion Laboratory (2015) Open source ↗
    INSTITUTION · CHECKED 2026-10-22 · ORIGINAL OFFLINE; WAYBACK MACHINE ARCHIVED COPY

How to read the labels

EstablishedSupported by strong, converging evidence.
ContestedEvidence exists but qualified scholars disagree.
UnresolvedThe question is open; evidence does not settle it.
LegendComes from myth, literature or tradition, not physical evidence.
SpeculativeA hypothesis with little direct evidence so far.

Hero image: Tabby's Star (KIC 8462852) in infrared and ultraviolet survey images. Image: Infrared: IPAC/NASA Ultraviolet: STScI (NASA) · Public domain · via Wikimedia Commons. Evidence labels describe the written claims, not the image. Version 1 · updated 2026-10-22.