Table 2. Comparison of 2003 & 2005 Oppositions of Mars

Mars in 2005 Compared to 2003*
Mars 2003   2005
Won't Be As Close     0.34 AU   0.46 AU (24% farther)
Appear as Bright mag. -2.9   mag. -2.3 (58% dimmer)
Appear as Large 25.1"   20.2" (20% smaller)
  Mars 2003   Mars 2005  
But Mars will appear much higher in USA skies
in 2005 compared with 2003! (Fig. 1),
and will not appear larger than 20 arc sec until 2018!


*Notes on Units
  1. Astronomical Unit (AU) Essentially the mean distance between Sun and Earth
      (about 93 million mi or 150 million km).
  2. magnitude (mag) An astronomical unit of brightness (brighter has lower assigned number).
    Learn more from this basic Sky & Telescope article.
  3. arc second (arc sec or " ) Angular unit of measure = 1/3600 of a degree (°).
     (Moon's angular diameter is about 1800 arc sec.    )
Go to AAC Mars 2005 Special Public Event Page

Last Update July 27, 2005