Making its closest approach to Earth since 2003, the planet Mars will put on quite a show this summer (1). The red planet will trek eastward and then loop backwards against the background of fixed stars, becoming steadily brighter as the distance from us shrinks (2). During this journey Mars will take on a color reminiscent of a luminous blood drop making it easy to see why ancient Roman and Greek observers associated this planet with their gods of war, Mars and Ares.
The realization that Mars was somewhat similar to our Earth and a close neighbor by astronomical standards has inspired interest and speculation in the general public as well as the scientific community. Much of the fascination and research has involved the prospect that Mars might harbor life. Over the centuries, scientific opinions on the prospects for life in our solar system have changed often as a consequence of new information gleaned with the use of improved technologies and instruments. Percival Lowell amassed visual telescopic observations and deduced from them he had glimpsed the evidence of global environmental/climate change and a planetary-scale engineering project. However, Lowell’s ideas were controversial from top to bottom and his 1908 book, Mars as the Abode of Life, was critiqued as a pseudoscientific bamboozling of a trusting public (3), the fake news of its day. Fifty years later investigators combining visual evidence with spectroscopic analyses posited large parts of Mars must be vegetated (4). These ideas were challenged and reinterpreted, but probably few things changed public perceptions more than the Mariner spacecraft missions which provided close-up views of a decidedly desolate looking planet.
Advanced civilizations and expansive, living forests have been ruled out, but exploration and the search for evidence of life on Mars has continued. Today, as a number of clever commentators have noted, Mars is the first planet we know to be inhabited by active robots from another world. Mars remains a high priority target for scientific researchers and organizations proposing to colonize it. It will be interesting to see how the demands of the various groups vying to conduct operations on Mars will be managed.
No special equipment will be necessary to observe this celestial spectacle and you can start following events immediately (2). Right now (February, 2018) at dawn Mars is in the southern sky in the constellation of Scorpius. This is a good time to see the planet fairly near the red giant star Antares, the heart of the scorpion and the ‘rival’ of Mars (5). To my eye, their magnitudes are well matched currently, but watch as Mars moves and changes in brightness and deepens in color. During the summer months when Mars is closest, persons in the Northern hemisphere should look low in the southern sky during the evening hours. For those with telescopes, this summer will be a prime time to train them on Mars. Truly close approaches like this occur only at 15-17 year intervals when even modestly-sized instruments will reveal polar ice caps, dark surface markings, clouds and perhaps gigantic dust storms.
June 24, 2018 – Looks like a gigantic dust storm has come to pass. In my telescope this morning Mars showed only an orange-tinted, featureless disk. Although sky conditions were nominal, I was unable to make out the polar ice cap which has been readily observable in the past.
(1) Deborah Byrd. Mars Brighter in 2018 Than Since 2003. EarthSky.org, 8 February 2018. http://earthsky.org/astronomy-essentials/why-is-mars-sometimes-bright-and-sometimes-faint
(2) Martin J. Powell. The Mars Apparition of 2017-2019. Naked Eye Planets.com http://www.nakedeyeplanets.com/mars.htm
(3) Eliot Blackwelder. Mars as the Abode of Life (review of the book written by Percival Lowell). Science 29:659-661. https://www.jstor.org/stable/pdf/1635385.pdf?refreqid=excelsior%3A6c4073f2a181a13f46bfe96497c24246
(4) William M. Sinton. Further Evidence of Vegetation on Mars. Science 130:1234-1237. http://science.sciencemag.org/content/sci/130/3384/1234.full.pdf
(5) Elizabeth Howell. Antares: Red Star at the End of its Life. Space.com, 17 August 2017. https://www.space.com/21905-antares.html