The Kuiper Belt and Olbers's paradox

Scott J. Kenyon, Rogier Windhorst

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


We investigate the constraints that Olbers's paradox, applied to the zodiacal background as measured from space, sets on outer solar system objects. If extended to very faint limits, R ∼ 40-50 mag, the steep optical number counts of Kuiper Belt objects (KBOs) at R ≲ 26 imply an infinitely bright night sky. Small KBOs with radii of r ∼ 1 μm to r ∼ 1 km must have a size distribution n(r) ∝ r-a, with a ∼ 3.4 or smaller to satisfy the known limits on the sky-surface brightness at optical and far-infrared wavelengths. Improved limits on the measured KBO surface brightness can yield direct estimates of the albedo, temperature, and size distribution for small KBOs in the outer solar system.

Original languageEnglish (US)
Pages (from-to)L69-L73
JournalAstrophysical Journal
Issue number1 PART 2
StatePublished - Jan 20 2001


  • Kuiper Belt
  • Solar system: Formation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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