We’ve reached the peak of the current Mars observing season with the planet closest to Earth:62-million km or 38.5-million miles on October 6/7th. At -2.5 magnitude and 22.6″ in diameter, Mars is a conspicuous, intense orange target in the sky that is brighter than any star, except our Sun and is only outshone by Venus and the Moon in the nighttime sky. When it reaches opposition next week, on October 13th, it will still be 22.4″ in diameter and a tad brighter at -2.6 magnitude. It will remain greater than 20″ in diameter for the whole month. So, weather permitting, put an eyepiece in the scope this month and show it to all your friends!
The public will likely learn from the media that the Mars Opposition is a “one-night” event, on October 13th, when the planet rises at sunset and is brighter and larger in appearance than usual. However, amateur astronomers know that the 2020 Mars Opposition is more like a “season,” where the planet grows in size each night over months, stays near peak size for a while, and then slowly fades away over the weeks. This gives us an observation window much longer than a single night!
Mars is growing daily in size and brightness as it approaches opposition night on 13 October 2020. On that date, the “Red Planet” will shine at magnitude -2.6 and be 22.4″ in diameter. At 5.5° above the Celestial Equator, it will be well placed for northern observers. Enjoy it while you can as it will not reach 22″ again until the year 2033! See our prior post on the Mars Opposition to learn why this will be the Last “Best” Mars Opposition for Northern Hemisphere!
The Mars 2020 opposition will be the “best” this decade for mid- and high-northern hemisphere observers.
Let’s start out by stating that the Mars 2020 opposition will be the “best” one this decade for mid- and high-northern hemisphere observers. (Better even than all the ones in the 2010’s!) On opposition night, 13 October 2020, the “Red Planet” will be brilliant in the sky at magnitude -2.6 and 22.4″ in diameter at a Declination of 5.5° above the Celestial Equator. It will reach 44° in elevation above the horizon in the city of London, UK.
(Due to the non-circular orbits of Earth and Mars, the instant of opposition is not usually the same as the closest approach between the pair: there can be a two-weeks difference in time. So, we’ll talk in round numbers when discussing the size of Mars around the time of opposition.)
With regard to this year’s event: yes, there have been “bigger” oppositions. In 2018 Mars was 24” in diameter (ranking with the super-duper, 2003 opposition that had Mars at 25″). However, while Mars was bigger in 2018, it was at -25.4° Declination and barely cleared your neighbor’s fence in the northern hemisphere. This year it’ll be +30.9 degrees higher in the sky!
Mars will exceed 24-arc-sec in diameter between July 23rd and August 9th, 2018. This is 97 percent of the maximum of 25.13-arc-sec diameter attained during the last of the ‘favorable’ apparitions, which occurred in 2003.Association of Lunar and Planetary Observers
At the end of this month, on July 27th, Mars will be in opposition and reach its greatest angular diameter — 24.3-arc-seconds — for the year. This is the best opposition since 2003. It’ll be greater than 21-arc-seconds tonight and well worth observing. For an explanation as to why some oppositions are better, what to expect from this year’s event, and accessories to better view and image Mars, see our blog post: Mars Opposition 2018 Preview.
Mars will be growing rapidly in apparent diameter in the weeks up to the big Mars Opposition on July 27, 2018. With Mars peaking this summer, Tele Vue Optics is making it easier to take a peek with rebates on 13mm and shorter focal length eyepieces for customers in the USA, US Territories, and those with APO/FPO Addresses.
About every 26-months, Earth and Mars get a good look at each other as their orbits cause them to line up together on the same side of the Sun. At the instant that Earth is between Mars and the Sun we have “Mars Opposition” — Mars is opposite the Sun in Earth’s sky. Mars is closest to Earth around this time and amateur astronomers make a point of observing it.