Bebhionn (moon)
Small irregular Saturnian moon, likely a contact binary.
NASA/Cassini · Public domain
Bebhionn (Saturn XXXVII) is a small, irregular moon of Saturn. Its discovery, from observations between December 2004 and March 2005, was announced in May 2005 by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, and Brian G. Marsden. The moon is roughly 6 kilometers in diameter. It orbits Saturn at an average distance of 16,898 Mm, completing one orbit in 820.130 days. Its orbit has an inclination of 41° to the ecliptic (18° to Saturn's equator) and an eccentricity of 0.469. The Cassini spacecraft’s ISS camera measured a rotation period of 16.33±0.03 hours. Bebhionn’s light curve indicates an elongated shape with major brightness variations, making it a strong candidate for a contact binary or binary moon.
The moon was named in April 2007 after Béibhinn (Béḃinn), an early Irish goddess of birth famed for her beauty. In Irish, the name is pronounced [ˈbʲeːvʲiːn̠ʲ] (southern accents, approximated as BAY-veen) or [ˈbʲeːvʲɪn̠ʲ] (northern accents, approximated as BAY-vin). The spelling "bh" (older "ḃ") indicates a softened "v" sound for the second consonant. The unusual spelling "Bebhionn" includes an extra "o" that is not pronounced, but suggests the final "nn" should be broad [n̪ˠ]. The name is still treated as a compound (sometimes spelled Bé Binn, etc.), so the unstressed vowel is not reduced to a schwa.
Quick Facts
- Named After
- Béibhinn
- Pronounced
- ˈ · b · eɪ · v · ɪ · n · BAY · vin
- Mpc Name
- Saturn XXXVII
- Discovered
- 2004
- Discoverer
- Scott S. Sheppard / David C. Jewitt / Jan T. Kleyna / Brian G. Marsden
- Inclination
- 35.01°
- Eccentricity
- 0.469
- Period
- −834.8 days
- Satellite Of
- Saturn
- Group
- Gallic group
- Rotation
- 16.33 · 0.03 h
- Albedo
- 0.06 (assumed)
Facts from the source article.
Lore & Background
Bebhionn was discovered by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, and Brian G. Marsden, with the discovery announced on 4 May 2005 based on observations taken between 12 December 2004 and 9 March 2005. It orbits Saturn at an average distance of 16,898 Mm in 820.130 days, with an inclination of 41° to the ecliptic (18° to Saturn's equator) and an eccentricity of 0.469. The moon is about 6 kilometers in diameter.
The rotation period of Bebhionn was measured at 16.33±0.03 hours by the ISS camera of the Cassini spacecraft. Its light curve reflects an elongated shape with large variations in brightness, making it a leading candidate for a contact binary or binary moon. The moon was named in April 2007 after Béibhinn, an early Irish goddess of birth renowned for her beauty. The spelling 'Bebhionn' reflects Irish pronunciation nuances, with the name still pronounced as a compound.
Reader's Guide
Bebhionn's significance lies in its status as a leading candidate for a contact binary or binary moon among Saturn's irregular satellites. The large variations in its light curve, observed by the Cassini spacecraft's ISS camera, indicate an elongated shape consistent with two bodies in contact or a binary system. This makes it a key object for understanding the formation and evolution of small bodies in the outer solar system, particularly the processes of accretion and collision that can produce such configurations. Its discovery, part of a batch of twelve new Saturnian satellites announced in 2005, expanded the known irregular moon population and highlighted the role of large-aperture surveys in finding faint, distant moons. The naming after an Irish goddess of birth adds cultural context, though the moon's physical characteristics remain the primary focus of scientific interest. The orbital parameters—high eccentricity and inclination—are typical of irregular satellites, suggesting capture from a heliocentric orbit. Bebhionn's rotation period of about 16.33 hours is relatively slow, which may be influenced by tidal forces or its binary nature.
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Frequently Asked Questions
What is Bebhionn?
Bebhionn is a tiny, irregularly shaped satellite of Saturn, measuring roughly 6 kilometers across. It is classified as Saturn XXXVII and is believed to be a contact binary, meaning two lobes have merged into a single body.
Who discovered Bebhionn and when was it announced?
The moon was identified from observations collected between December 2004 and March 2005, and its discovery was formally announced on 4 May 2005 by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, and Brian G. Marsden.
How does Bebhionn orbit Saturn?
It circles Saturn at a mean distance of about 16,898 million meters, taking roughly 820 days to complete one revolution. Its path is notably tilted at 41 degrees relative to the ecliptic plane and carries a high eccentricity of 0.469, giving it an elongated, non-circular track.
What is Bebhionn's shape and rotation like?
Cassini's ISS camera determined a rotation period of approximately 16.33 hours, and the moon's light curve reveals an elongated silhouette consistent with a contact-binary form. This lumpy, peanut-like geometry is typical of very small, loosely bound icy bodies.
Why is Bebhionn interesting to Saturn-moon enthusiasts?
As one of dozens of small irregular satellites, Bebhionn helps researchers piece together the capture history of objects that were likely not formed alongside Saturn itself. Its extreme orbital tilt and eccentricity make it a useful data point for modeling how such distant, chaotic moons remain gravitationally bound over billions of years.
More in Moons of Saturn 1-24
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