S/2020 S 4

Last updated
S/2020 S 4
Discovery 
Discovered by Edward Ashton, Brett J. Gladman
Discovery date2020
Orbital characteristics  
18,235,500  km (11,331,000 mi) [1]
Eccentricity 0.495
2.538 yrs (926.92 d) [1]
Inclination 40.1° (to the ecliptic)
Satellite of Saturn
Group Gallic group
Physical characteristics
Mean diameter
3 km
17.0

    S/2020 S 4 is the faintest natural satellite of Saturn. It was discovered by Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on June 24, 2020, and was announced on May 6, 2023 by the IAU Minor Planet Center after observations were collected over a long period of time to confirm the satellite's orbit that were taken between July 1, 2019 and July 9, 2021. [2]

    Contents

    Orbit

    S/2020 S 4 is a highly eccentric satellite with an eccentricity of 0.495, it orbits Saturn at an average distance of 18.2 million km and an orbital period of 2 and a half years, with an inclination of 40.1 to the ecliptic, suggesting that it belongs to the Gallic group. [1] However, sometimes it's moon group is disputed like S/2019 S 6, and includes it to the Inuit group that it was a fragment piece of Siarnaq that broke off a long time ago in a few thousand year time-span. [3] [4]

    Physical Characteristics

    S/2020 S 4 is estimated to be 3 km in diameter and currently the faintest known moon of Saturn having an absolute magnitude of 17. [1] Scott S. Sheppard and Tilmann Denk on the other hand, is estimated to be 2 km and 2 and a quarter km, respectively. [3] [4] If these estimates were true, it makes S/2020 S 4 one of the smallest known irregular moons of Saturn. [3]

    Related Research Articles

    <span class="mw-page-title-main">Moons of Saturn</span> Natural satellites of the planet Saturn

    The moons of Saturn are numerous and diverse, ranging from tiny moonlets only tens of meters across to the enormous Titan, which is larger than the planet Mercury. There are 146 moons with confirmed orbits, the most of any planet in the solar system. This number does not include the many thousands of moonlets embedded within Saturn's dense rings, nor hundreds of possible kilometer-sized distant moons that were seen through telescopes but not recaptured. Seven Saturnian moons are large enough to have collapsed into a relaxed, ellipsoidal shape, though only one or two of those, Titan and possibly Rhea, are currently in hydrostatic equilibrium. Three moons are particularly notable. Titan is the second-largest moon in the Solar System, with a nitrogen-rich Earth-like atmosphere and a landscape featuring river networks and hydrocarbon lakes. Enceladus emits jets of ice from its south-polar region and is covered in a deep layer of snow. Iapetus has contrasting black and white hemispheres as well as an extensive ridge of equatorial mountains among the tallest in the solar system.

    <span class="mw-page-title-main">Siarnaq</span> Moon of Saturn

    Siarnaq, also designated Saturn XXIX, is the second-largest irregular moon of Saturn. It was discovered on 23 September 2000 by a team of astronomers led by Brett J. Gladman. It was named after the Inuit goddess of the sea, Siarnaq, who is more commonly known as Sedna. Siarnaq is the largest member of Saturn's Inuit group of prograde irregular moons, which orbit far from Saturn in the same direction as the planet's rotation. The moons of the Inuit group are believed to have originated as fragments from the collisional breakup of a larger progenitor moon after it was gravitationally captured into orbit around Saturn several billion years ago. Several other small Inuit group moons share similar orbits to Siarnaq, indicating that the moon had experienced another collision after forming from its progenitor.

    Fenrir, or Saturn XLI, is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, and Brian G. Marsden on May 4, 2005, from observations taken between December 13, 2004, and March 5, 2005. Fenrir has an apparent magnitude of 25, making it one of the faintest known moons in the Solar System, and was discovered using some of the largest telescopes in the world. It is even too dark to have been observed by the Cassini spacecraft when it was in orbit around Saturn, for which it never got brighter than approximately 17th apparent magnitude. Fenrir was named after Fenrisulfr, a giant wolf from Norse mythology, father of Hati and Skoll, son of Loki, destined to break its bonds for Ragnarök.

    <span class="mw-page-title-main">Norse group</span> Category of satellites of Saturn

    The Norse group is a large group of retrograde irregular satellites of Saturn. Their semi-major axes range between 12 and 27 Gm, their inclinations between 136° and 178° and their eccentricities between 0.06 and 0.63. Unlike the Inuit and Gallic groups, the orbital parameters are widely dispersed and the group is likely to be composed from a number of subgroups with more homogeneous orbital and physical parameters. The International Astronomical Union (IAU) reserves names taken from Norse mythology for these moons. The exception is Phoebe, the largest, which was discovered long before the others.

    <span class="mw-page-title-main">Irregular moon</span> Captured satellite following an irregular orbit

    In astronomy, an irregular moon, irregular satellite, or irregular natural satellite is a natural satellite following a distant, inclined, and often highly elliptical and retrograde orbit. They have been captured by their parent planet, unlike regular satellites, which formed in orbit around them. Irregular moons have a stable orbit, unlike temporary satellites which often have similarly irregular orbits but will eventually depart. The term does not refer to shape; Triton, for example, is a round moon but is considered irregular due to its orbit and origins.

    S/2007 S 5 is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on May 3, 2023 from observations taken between January 5, 2005 and July 9, 2021.

    S/2020 S 7 is a natural satellite of Saturn. Its discovery was announced by Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on May 10, 2023 from observations taken between July 1, 2019 and July 24, 2020.

    S/2019 S 14 is a natural satellite of Saturn. Its discovery was announced by Edward Ashton and Brett J. Gladman on May 10, 2023 from observations taken between July 1, 2019 and July 9, 2021.

    S/2020 S 3 is a natural satellite of Saturn. Its discovery was announced by Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on May 5, 2023 from observations taken between July 3, 2019 and July 9, 2021.

    S/2019 S 6 is a natural satellite of Saturn. Its discovery was announced by Edward Ashton and Brett J. Gladman on May 8, 2023 from observations taken between July 3, 2019 and July 8, 2021.

    S/2020 S 5 is a natural satellite of Saturn. Its discovery was announced by Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on May 6, 2023 from observations taken between July 3, 2019 and July 9, 2021.

    S/2004 S 43 is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on May 7, 2023 from observations taken between December 12, 2004 and July 9, 2021.

    S/2019 S 11 is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on May 8, 2023 from observations taken between January 5, 2005 and August 16, 2020.

    S/2019 S 13 is a natural satellite of Saturn. Its discovery was announced by Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on May 9, 2023 from observations taken between July 3, 2019 and July 8, 2021.

    S/2005 S 5 is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on May 10, 2023 from observations taken between March 9, 2005 and July 24, 2020.

    S/2006 S 18 is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on May 15, 2023 from observations taken between December 14, 2004 and July 9, 2021.

    S/2006 S 19 is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on May 15, 2023 from observations taken between January 5, 2006 and July 9, 2021.

    S/2020 S 9 is a natural satellite of Saturn. Its discovery was announced by Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on May 15, 2023 from observations taken between August 23, 2019 and August 16, 2020.

    S/2019 S 21 is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, Edward Ashton, Brett J. Gladman, Jean-Marc Petit and Mike Alexandersen on May 16, 2023 from observations taken between February 2, 2006 and July 8, 2021.

    S/2004 S 52 is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, Edward Ashton, Brett J. Gladman and Mike Alexandersen on May 15, 2023 from observations taken between December 12, 2004 and July 24, 2020.

    References

    1. 1 2 3 4 "Planetary Satellite Mean Elements". Jet Propulsion Laboratory. California Institute of Technology. Retrieved 6 May 2023.
    2. ↑ "MPEC 2023-J38 : S/2020 S 4". Minor Planet Electronic Circular. Minor Planet Center. Retrieved 6 May 2023.
    3. 1 2 3 "S/2020 S 4". Tilmann's Website. Tilmann Denk. Retrieved 23 March 2024.
    4. 1 2 "Saturn Moons". Carnegie Science. Earth & Planets Laboratory. Retrieved 23 March 2024.
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