Uranus New Rings and Moons
Showalter leads Hubble observations revealing two previously unknown dusty rings around Uranus and the moons Mab and Cupid.
Historical biography archive · Updated 2026-11-03
Mark Showalter Biography and Timeline
Follow Mark Showalter through 13 dated historical records for United States of America.
Mark Showalter, historical timeline
A chronological timeline drawn from matching World History Database records.
13Distinct records
1 of 1Page
2005–2019Years on this page
2005
2011
Kerberos
A Hubble search led by Mark Showalter discovers a fourth moon of Pluto, later named Kerberos.
Kerberos
A follow-up Hubble image confirms the newly detected fourth Pluto moon.
Kerberos
A further Hubble observation again confirms the fourth Pluto moon and strengthens its orbital solution.
2012
Styx
A Hubble hazard survey discovers Pluto's fifth and smallest known moon, later named Styx.
2013
Discovery of Hippocamp
Showalter discovers a tiny Neptunian moon in archival Hubble images and initially designates it S/2004 N 1.
Pluto Moons
The names Kerberos and Styx are adopted for Pluto's fourth and fifth known moons, previously called P4 and P5.
Hippocamp Orbit
Showalter determines a circular orbit for the newly detected moon by tracing it through many archival Hubble images.
2015
Pluto Moons
Analysis of the small moons shows rapid, non-synchronous rotation rather than the simple tidal locking seen in Pluto and Charon.
2017
Pluto
The International Astronomical Union approves the first official names for surface features discovered on Pluto by New Horizons.
Pluto
Tombaugh Regio and Burney crater become official Pluto feature names honoring Clyde Tombaugh and Venetia Burney.
2019
Hippocamp Named
The tiny moon discovered in Hubble images receives the official name Hippocamp.
Hippocamp Origin
Showalter's analysis supports the idea that Hippocamp may be debris broken from the larger moon Proteus by an ancient impact.
Records, sources and methodology
These dates and descriptions come from the historical_events database. Exact duplicate records have been collapsed. Names are grouped by the country, Name 2 and Name 1 fields; records with missing Name 2 cannot be reliably assigned to an individual biography. Check the underlying sources before formal citation.