Red planet over red star

Mars is passing the magnificent star called Antares, “anti-Mars.” The middle of Sep. 28 by Universal Time is when they are closest together, so they are nearly at their closest on the evenings of Sep. 27 and 28.

140928MarsAntaresThe conjunction of Mars with this or any star happens at intervals of about 23 months, Mars’s cycle around the Sun. The way it looks from Earth varies according to Earth’s own position at the time. Last time, on 2012 Oct. 20, Mars passed 3.6 degrees north of Antares, and they appeared 42 degrees east (left) of the Sun. This time, they are 65 degrees from the Sun, therefore more conveniently high in a darker post-sunset sky; and Mars is passing slightly closer north of the star, 3.1 degrees. But that is still a wide gap (about 1,900 times the width of Mars’s tiny 6-second disk). Mars is moving east at less than 3/4 of a degree a day.

Planet and star appear equal in brightness; Mars is brighter by an amount imperceptible to the naked eye (their magnitudes are 0.8 and 1.0). This is despite an enormous difference of distance! Mars at this time is 1.52 Sun-Earth distances from us (the Sun-Earth distance, or astronomical unit, is 93 million miles). Antares is at 600 light-years – about 25 million times farther.

Antares is the southernmost of the four great stars that lie close to the path of the Sun, Moon, and planets (the others being Aldebaran, Regulus, and Spica). It lurks ruddily in the lower sky; I love the many other names for it that you can extract, a little shakily, from R.H. Allen’s fine old book on star names – the Heart of the Scorpion, of course, and Tyrannus, the Rebel, the Bat Star, Vespertilio, the Rustle of Evening.

There is a box in Astronomical Calendar 2014 about Antar, the black “Arabian Hercules,” pre-Islamic hero-poet to whom some, entertainingly though presumably falsely, attribute the name of the star.

When I came upstairs from writing this to breakfast, the radio was playing over and over the ominous gallop of “Mars, the Bringer of War”: someone was giving an analytical review of many orchestras’ recordings of Holst’s “The Planets.”

2 thoughts on “Red planet over red star”

  1. A Lifetime of Mars Observing ~
    The next conjunction of Mars and Antares in 2016 will closely follow a very good Martian opposition in eastern Libra, so Mars will be considerably brighter then. The 2016 opposition will be the first of three near-perihelic oppositions (2016, 2018, and 2020) which will afford excellent chances to observe the planet. I remember watching Mars in 1971 and 1973 as an eight (and then ten) year old boy with my father. Then in 1986 (very low in German skies) and 1988 from Biloxi, Mississippi. I saw the most recent cycle of perihelic oppositions in 2001, 2003 and 2005 from Virginia. Being 51 years old now, I wonder how many more of these brief looks at a 22+ arc-second Mars will I have . . . . ? Yet another example of how astronomy humbles and offers perspective, as Guy so often alludes to.

  2. The nights around October 25 find Mars moving below the star forming nebula M8. This will make an interesting binocular sight as well as a photo opportunity.

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