Anthe (moon)

Anthe

Anthe is the object in the center.
Discovery
Discovered by	Cassini Imaging Team [1]
Discovery date	May 30, 2007
Designations
Designation	Saturn XLIX
Pronunciation	/ˈænθiː/[a]
Named after	Άνθη Anthē
Adjectives	Anthean /ænˈθiːən/
Orbital characteristics [2]
Semi-major axis	197,700 km
Eccentricity	0.0011
Orbital period (sidereal)	1.05089 d
Average orbital speed	13.824 km/s
Inclination	0.1° to Saturn's equator
Satellite of	Saturn
Physical characteristics
Mean radius	0.75–2.4 km[3]
Mean density	0.5 g/cm3 (assumed)[4]
Synodic rotation period	assumed synchronous
Axial tilt	assumed zero
Albedo	0.25–1 (geometric)[3]

Anthe /ˈænθiː/ is a very small natural satellite of Saturn lying between the orbits of Mimas and Enceladus. It is also known as Saturn XLIX; its provisional designation was S/2007 S 4. It is named after one of the Alkyonides; the name means flowery. It is the sixtieth confirmed moon of Saturn.^[5]

The designation S/2007 S 4 was also accidentally and incorrectly used for a different Saturnian satellite discovered later. The published discovery was retracted a few hours later and republished the next day under the correct name of S/2007 S 5.

It was discovered by the Cassini Imaging Team^[1] in images taken on 30 May 2007.^[2] Once the discovery was made, a search of older Cassini images revealed it in observations from as far back as June 2004. It was first announced on 18 July 2007.^[2]

Anthe is visibly affected by a perturbing 10:11 mean-longitude resonance with the much larger Mimas. This causes its osculating orbital elements to vary with an amplitude of about 20 km in semi-major axis on a timescale of about 2 Earth years. The close proximity to the orbits of Pallene and Methone suggests that these moons may form a dynamical family.

The ratio of Anthe's medium axis to its long axis is ≈0.7, and the ratio of its short axis to its medium axis is ≈0.95. This implies that it has a similar shape to Methone.^[6]

Material blasted off Anthe by micrometeoroid impacts is thought to be the source of the Anthe Ring Arc, a faint partial ring about Saturn co-orbital with the moon first detected in June 2007.^[7][8]

• "Cassini Imaging Science Team". Cassini Imaging Central Laboratory for OPerationS. Archived from the original on 2011-05-20. Retrieved 2012-01-01.
• Agle, D. C. (July 19, 2007). "Saturn Turns 60". Cassini Solstice Mission. JPL/NASA. Archived from the original on February 20, 2012. Retrieved 2012-01-01.
• Green, Daniel W. E. (July 18, 2007). "S/ 2007 S 4". IAU Circular. 8857. Retrieved 2012-01-01.
• Hedman, M. M.; Murray, C. D.; Cooper, N. J.; Tiscareno, M. S.; Beurle, K.; Evans, M. W.; Burns, J. A. (2008-11-25). "Three tenuous rings/arcs for three tiny moons". Icarus. 199 (2): 378–386. Bibcode:2009Icar..199..378H. doi:10.1016/j.icarus.2008.11.001. ISSN 0019-1035.
• Porco C. C.; et al. (2008-09-05). "More Ring Arcs for Saturn". Cassini Imaging Central Laboratory for Operations. Archived from the original on 2008-10-10. Retrieved 2008-09-05.
• Thomas, P. C.; Helfenstein, P. (July 2020). "The small inner satellites of Saturn: Shapes, structures and some implications". Icarus. 344: 20. Bibcode:2020Icar..34413355T. doi:10.1016/j.icarus.2019.06.016. S2CID 197474587. 113355.
• Thomas, P. C.; Burns, J. A.; Hedman, M.; Helfenstein, P.; Morrison, S.; Tiscareno, M. S.; Veverka, J. (2013-09-01). "The inner small satellites of Saturn: A variety of worlds". Icarus. 226 (1): 999–1019. doi:10.1016/j.icarus.2013.07.022. ISSN 0019-1035.

Media related to Anthe at Wikimedia Commons

• From Dark Obscurity... A Tiny New Saturnian Moon Comes To Light Archived 2011-02-02 at the Wayback Machine