5 Astraea

Astraea was the fifth asteroid discovered, on 8 December 1845, by Karl Ludwig Hencke and named for 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.{{Cite web | title = Dawn Community | publisher = NASA | url = http://dawn.jpl.nasa.gov/DawnCommunity/flashbacks/fb_09.asp | access-date = 17 April 2009 | archive-url = https://web.archive.org/web/20090521235728/http://dawn.jpl.nasa.gov/DawnCommunity/flashbacks/fb_09.asp | archive-date = 21 May 2009 | url-status = dead }}

Hencke's symbol for Astraea is an inverted anchor, in the pipeline for Unicode 17.0 as U+1F778 🝸 (12px),{{cite web |url=https://www.unicode.org/L2/L2023/23207-historical-asteroids.pdf |title=Unicode request for historical asteroid symbols |last1=Bala |first1=Gavin Jared |last2=Miller |first2=Kirk |date=18 September 2023 |website=unicode.org |publisher=Unicode |access-date=26 September 2023 |quote=}}{{cite web |url=https://unicode.org/alloc/Pipeline.html |title=Proposed New Characters: The Pipeline |author=Unicode |date= |website=unicode.org |publisher=The Unicode Consortium |access-date=6 November 2023 |quote=}} though given Astraea's role with justice and precision, it is perhaps a stylized set of scales, or a typographic substitute for one.

{{cite book

| title = Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königl. Preuss. Akademie der Wissenschaften zu Berlin

| date = 1845

| page = 406

| publisher = Deutsche Akademie der Wissenschaften zu Berlin; Königlich Preussische Akademie der Wissenschaften zu Berlin

| url = https://books.google.com/books?id=ZM8DAAAAMAAJ&pg=PA406

| quote = 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.

}}{{cite book

| last = Schmadel | first = Lutz D.

| date = 2003

| title = Dictionary of Minor Planet Names

| publisher = Springer

| pages = 15–18

| isbn = 978-0-354-06174-2

}}

This symbol is no longer used. The astrological symbol is a percent sign, encoded specifically at U+2BD9 ⯙:{{cite web|url=https://www.unicode.org/L2/L2016/16080r-add-astrology.pdf|title=L2/16-080: Additional Symbols for Astrology|date=2016-05-28|first=David|last=Faulks}} it is simply shift-5 on the keyboard, because Astraea was the fifth asteroid discovered. 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.{{Cite web|title=The Planet Hygea|date=1849|work=spaceweather.com|url=http://spaceweather.com/swpod2006/13sep06/Pollock1.jpg|access-date=18 April 2008| archive-url= https://web.archive.org/web/20080409071528/http://spaceweather.com/swpod2006/13sep06/Pollock1.jpg| archive-date= 9 April 2008 | url-status= live}} 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) 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.

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. This gives an axial tilt of about 33°.{{Cn|date=March 2024}} 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 {{nowrap|115 ± 6 km}}.{{cite journal

|display-authors=6

|last=Ďurech

|first=Josef

|author2=Kaasalainen, Mikko

|author3=Herald, David

|author4=Dunham, David

|author5=Timerson, Brad

|author6=Hanuš, Josef

|author7=Frappa, Eric

|author8=Talbot, John

|author9=Hayamizu, Tsutomu

|author10=Warner, Brian D.

|author11=Pilcher, Frederick

|author12=Galád, Adrián

|title=Combining asteroid models derived by lightcurve inversion with asteroidal occultation silhouettes

|journal=Icarus

|volume=214

|issue=2

|pages=652–670

|date=2011

|url=http://astro.troja.mff.cuni.cz/projects/asteroids3D/download/durech_et_al_2011_occ_paper.pdf

|doi=10.1016/j.icarus.2011.03.016

|arxiv=1104.4227

|bibcode=2011Icar..214..652D

|access-date=26 January 2012

|archive-url=https://web.archive.org/web/20160303214312/http://astro.troja.mff.cuni.cz/projects/asteroids3D/download/durech_et_al_2011_occ_paper.pdf

|archive-date=3 March 2016

|url-status=dead

}}

{{multiple image

|direction = horizontal

|align= left

|width1= 320

|width2= 180

|image1=Moon and Asteroids 1 to 10.svg

|image2=AstraeaOrbit.png

|footer= 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.

}}

{{clear|left}}

• Former classification of planets

{{reflist|30em|refs=

{{cite web

|type = 2017-11-22 last obs.

|title = JPL Small-Body Database Browser: 5 Astraea

|url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2000005

|publisher = Jet Propulsion Laboratory

|access-date = 1 June 2018}}

{{cite book

|title = Dictionary of Minor Planet Names – (5) Astraea

|last = Schmadel | first = Lutz D.

|publisher = Springer Berlin Heidelberg

|page = 15

|date = 2007

|isbn = 978-3-540-00238-3

|doi = 10.1007/978-3-540-29925-7_6 |chapter = (5) Astraea }}

{{cite web

|title = 5 Astraea

|work = Minor Planet Center

|url = https://www.minorplanetcenter.net/db_search/show_object?object_id=5

|access-date = 1 June 2018}}

{{cite web

|title = Asteroid (5) Astraea – Proper Elements

|publisher = AstDyS-2, Asteroids – Dynamic Site

|url = https://newton.spacedys.com/astdys/index.php?n=5&pc=1.1.6

|access-date = 25 May 2018}}

{{cite journal

|first1 = E. F. |last1 = Tedesco

|first2 = P. V. |last2 = Noah

|first3 = M. |last3 = Noah

|first4 = S. D. |last4 = Price

|date = October 2004

|title = IRAS Minor Planet Survey V6.0

|url = https://sbnarchive.psi.edu/pds3/iras/IRAS_A_FPA_3_RDR_IMPS_V6_0/data/diamalb.tab

|journal = NASA Planetary Data System

|volume = 12

|pages = IRAS-A-FPA-3-RDR-IMPS-V6.0

|bibcode = 2004PDSS...12.....T

|access-date = 22 October 2019}}

{{Cite journal

|last=Fienga |first=A.

|last2=Avdellidou |first2=C.

|last3=Hanuš |first3=J.

|date=February 2020

|title=Asteroid masses obtained with INPOP planetary ephemerides

|url=https://academic.oup.com/mnras/article/492/1/589/5658701

|journal=Monthly Notices of the Royal Astronomical Society

|volume=492

|issue=1

|doi=10.1093/mnras/stz3407

|doi-access=free}}

}}

• [http://www.lesbeninger.com/astraea.html 2 Telescope images of 5 Astraea]
• [http://adsabs.harvard.edu//full/seri/MNRAS/0007//0000027.000.html MNRAS 7 (1846) 27]
• [https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=5+Astraea Physical characteristics of (5) Astraea] at the Small Bodies Data Ferret
• [https://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html Discovery Circumstances: Numbered Minor Planets (1)-(5000)] – Minor Planet Center
• [https://books.google.com/books?id=aeAg1X7afOoC&pg Dictionary of Minor Planet Names], Google books
• {{AstDys|5}}
• {{JPL small body}}

{{Use dmy dates|date=September 2019}}

{{Minor planets navigator |4 Vesta |number=5 |6 Hebe}}

{{Authority control}}

{{DEFAULTSORT:000005}}

Category:Astraea asteroids

Astraea

Astraea

Category:S-type asteroids (SMASS)

Category:S-type asteroids (Tholen)

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