Mars at opposition in 2018

Mars will be at opposition this July 31, also the planet will appear brightest from July 27 to July 30, when this is at its closest approach to earth this time, there will a distance of 57.6 million kilometres between the two rocky worlds. Mars reaches its highest point around midnight about 35 degrees above the southern horizon, or one third of the distance between the horizon and overhead. The red planet will be visible for much of the night, by mid-August, Mars will become fainter. Unfortunately, the recent global storm (an event that occurs between 6 to 8 years) will make harder to see it features. 

This opposition is the end of the upswing cycle of Mars’s 16-year period, from now on the close encounter will appear smaller. Due to the eccentricity of the planets' orbits, some oppositions are more favourable than others, something particularly true for Mars, whose orbit is quite eccentric, resulting in a considerably variation of distance between Mars and the Earth from one opposition to the next. The next Mars Close Approach will be on October 6, 2020. The 2018 opposition is the brightest and the biggest Mars will be since 2003, and will not be seen better than this until 2035.

The oppositions happen in groups of two or three which repeating at intervals of 15 years and 17 years. The time between successive oppositions (known as the synodic period) varies between 765 and 800 days, averaging around 780 days or a little over 2 years. It appears that perihelic oppositions seen to take place in the constellations of Capricornus or Aquarius, whilst aphelic oppositions take place in Leo. Mars at opposition varies from around 0.3728 Astronomical Units (55.7 million kms) at perihelion to 0.6780 AU (101.4 million kms) at aphelion. The maximum theoretical apparent size of Mars when seen from the Earth is a little under 26" (26 arcseconds, where 1 arcsecond = 1/3600th of a degree) 

2018 Opposition 

Distance from observer:   0.384969773 au 

Distance from Sun:           1.396779920 au 

Mars Radius:                     3397 km 

Apparent magnitude:         -2.76 

Orbit size:                         1.5237 au 

Angular size:                     24 arcseconds 

Constellation:                    Capricornus 

Mars Earth Comparison

	Earth	Mars
Radius (km)	6,370	3,390
Surface gravity (g)	1	0.4
Solar irradiance (watts per square metre)	1,360	590
Atmospheric pressure (kilopascals)	101	0.6
Perihelion distance to Sun (AU)	0.98	1.38
Aphelion distance to Sun (AU)	1.02	1.67
Length of year (days)	365	687
Length of day (hours)	24	24.6
Axial tilt (degrees)	23	25

Sources: ALPO, NASA, nakedeyeplanets, Wikipedia,