5 Astraea

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This article is about the asteroid. For other uses, see Astraea (disambiguation).
5 Astraea
Synodic rotation period
0.700 04 d (16.801 h)[7]
Equatorial rotation velocity
6.49 m/s[a]
North pole right ascension
115°/310° ± 5°
North pole declination
55° ± 5°
0.227[9]
S
8.74 to 12.89
6.85
0.15" to 0.041"

Astraea (

Tholen classification system.[4]

Discovery and name

Astraea was the fifth asteroid discovered, on 8 December 1845, by

Astraea, a Greek goddess of justice named after the stars. It was his first of two asteroid discoveries. The second was 6 Hebe. A German amateur astronomer and post office headmaster, Hencke was looking for 4 Vesta when he stumbled on Astraea. The King of Prussia awarded him an annual pension of 1200 marks for the discovery.[10]

Hencke's symbol for Astraea is an inverted anchor, in the pipeline for Unicode 17.0 as U+1F778 🝸 (),[11][12] though given Astraea's role with justice and precision, it is perhaps a stylized set of scales, or a typographic substitute for one.[13][14] This symbol is no longer used. The astrological symbol is a percent sign, encoded specifically at U+2BD9 ⯙.[15] The modern astronomical symbol is a simple encircled 5 (⑤).

For 38 years after the discovery of the fourth known asteroid, Vesta, in 1807, no further asteroids were discovered.[16] After the discovery of Astraea, 8 more were discovered in the following 5 years, and 24 were found in the 5 years after that. The discovery of Astraea proved to be the starting point for the eventual demotion of the four original asteroids (which were regarded as planets at the time)[16] to their current status, as it became apparent that these four were only the largest of a new type of celestial body with thousands of members.

Characteristics

Photometry indicates

prograde rotation, that the north pole points in the direction of right ascension 115° or 310° and declination 55°, with a 5° uncertainty.[7] This gives an axial tilt of about 33°.[citation needed] With an apparent magnitude of 8.7 (on a favorable opposition on 15 February 2016), it is only the seventeenth-brightest main-belt asteroid, and fainter than, for example, 192 Nausikaa or even 324 Bamberga
(at rare near-perihelion oppositions).

An stellar occultation on 6 June 2008 allowed Astraea's diameter to be estimated; it was found to be 115 ± 6 km.[17]

Left: A size comparison of the first 10 numbered asteroids profiled against Earth's Moon.
Right: The orbit of 5 Astraea in white compared with those of Earth, Mars and Jupiter.

See also

Notes

  1. ^ a b c Calculated based on the known parameters
  2. ^ Assuming a diameter of 114 ± 4 km.

References

  1. ^ a b "5 Astraea". Minor Planet Center. Retrieved 1 June 2018.
  2. ^ "Astraea". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 22 March 2020.
  3. ISBN 978-3-540-00238-3
    .
  4. ^ a b c "JPL Small-Body Database Browser: 5 Astraea" (2017-11-22 last obs.). Jet Propulsion Laboratory. Retrieved 1 June 2018.
  5. ^ "Asteroid (5) Astraea – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 25 May 2018.
  6. ^ "AstDyS-2 Astraea Synthetic Proper Orbital Elements". Department of Mathematics, University of Pisa, Italy. Retrieved 1 October 2011.
  7. ^
    doi:10.1016/j.pss.2005.04.010
    .
  8. ^
    doi:10.1093/mnras/stz3407
    .
  9. Bibcode:2004PDSS...12.....T
    . Retrieved 22 October 2019.
  10. ^ "Dawn Community". NASA. Archived from the original on 21 May 2009. Retrieved 17 April 2009.
  11. ^ Bala, Gavin Jared; Miller, Kirk (18 September 2023). "Unicode request for historical asteroid symbols" (PDF). unicode.org. Unicode. Retrieved 26 September 2023.
  12. ^ Unicode. "Proposed New Characters: The Pipeline". unicode.org. The Unicode Consortium. Retrieved 6 November 2023.
  13. ^ Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königl. Preuss. Akademie der Wissenschaften zu Berlin. Deutsche Akademie der Wissenschaften zu Berlin; Königlich Preussische Akademie der Wissenschaften zu Berlin. 1845. p. 406. Der Planet hat mit Einwilligung des Entdeckers den Namen Astraea erhalten, und sein Zeichen wird nach dem Wunsche des Hr. Hencke ein umgekehrter Anker sein.
  14. ISBN 978-0-354-06174-2
    .
  15. ^ Faulks, David (28 May 2016). "L2/16-080: Additional Symbols for Astrology" (PDF).
  16. ^ a b "The Planet Hygea". spaceweather.com. 1849. Archived from the original on 9 April 2008. Retrieved 18 April 2008.
  17. doi:10.1016/j.icarus.2011.03.016. Archived from the original
    (PDF) on 3 March 2016. Retrieved 26 January 2012.

External links

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