Fobos je otkrio [[Astronomija|astronom]] [[Asaph Hall]] [[18. 8.|18. augusta]] 1877, posmatrajući iz Mornaričke opservatorije [[Sjedinjene Američke Države|SAD]]-a u [[Washington D.C.|Vašingtonu]].<ref>{{Cite journal|url=http://adsabs.harvard.edu//full/seri/Obs../0001//0000181.000.html|title=Notes: The Satellites of Mars|journal=The Observatory|volume=1|issue=6|date = 1877-09-20.09. 1877.|pages=181–185|accessdate = 4. 2009-02.-04 2009.|bibcode = 1877Obs.....1..181. }}</ref><ref>{{Cite journal|url=http://adsabs.harvard.edu//full/seri/AN.../0091//0000013.000.html|title=Observations of the Satellites of Mars|last=Hall|first=A.|publisher=Astronomische Nachrichten|volume=91 |issue=2161|pages=11/12–13/14 |date = 1877-10-17. 10. 1877., signed September 21, 1877|accessdate = 4. 2009-02. 2009.-04}}</ref><ref name="Morley1989">{{Cite journal|last=Morley|first=T. A.|url=http://adsabs.harvard.edu//full/seri/A+AS./0077//0000220.000.html|title=A Catalogue of Ground-Based Astrometric Observations of the Martian Satellites, 1877-1982|journal=Astronomy and Astrophysics Supplement Series (ISSN 0365-0138)|volume=77|issue=2|month=February|year=1989|pages=209–226}} (Table II, p. 220: first observation of Phobos on August 18, 1877.38498)</ref> Hall je otkrio i Deimos, Marsov drugi mjesec. Nazive je predložio Henry Madan ([[1838]]–[[1901]]), [[doktor]] nauka na [[Eton College|Etonu]], zasnivajući svoj prijedlog na 15. pjevanju [[Ilijada|Ilijade]], u kojem Ares poziva Užasa (Deimos) i Straha (Phobos).<ref>{{Cite journal|last=Madan|first=H. G.|url=http://books.google.com/?id=fC4CAAAAYAAJ&pg=RA4-PA475&lpg=RA4-PA475|journal=Nature|volume=16|issue=414|title=Letters to the Editor: The Satellites of Mars|date = 4. 1877-10. 1877., signed September 29, 1877-04|pages=475|doi=10.1038/016475b0|publisher=Macmillan Journals ltd.|bibcode = 1877Natur..16R.475M }}</ref><ref>{{Cite journal|last=Hall|first=A.|url=http://adsabs.harvard.edu//full/seri/AN.../0092//0000031.000.html|journal=Astronomische Nachrichten|volume=92|issue=2187|title=Names of the Satellites of Mars|date = 1878-03-14. 03. 1878., signed February 7, 1878|pages=47–48|doi=10.1002/asna.18780920304|bibcode=1878AN.....92...47H}}</ref>
== Fizikalne karakteristike ==
Red 145:
| title = Precise mass determination and the nature of Phobos | journal = [[Geophysical Research Letters]]
| doi = 10.1029/2009GL041829 | id = | accessdate = 01. 10. 2010.-10-01 | bibcode=2010GeoRL..3709202A}}</ref>
[[Infracrveno zračenje|Infracrvena]] snimanja Fobosa sugeriraju da je sastavljen od [[silikati|silikatnih]] [[minerali|minerala]], koji su poznati s površine Marsa. Spektri se razlikuju od spektara svih klasa hondritnih [[meteorit]]a, što još jednom smanjuje mogućnost [[asteroid]]nog porijekla ovog satelita.<ref name = "Giuranna">{{Cite conference
