Mars, Antares, Moon triangle

Event Date: October 18th

Time: 7:00 PM

Brief

   Let's close out the Moon/Antares/Mars combo series, by showing the Moon in a position that lets us see all three within a binocular field.  Through an 8º, or more easily 9º field of view as image two shows, we can fit all three.  As the waxing, crescent moon has moved past both, it creates a triangle with the three.  As it moves further east each day now, that triangle disappears, while Mars continues to creep up on similar-looking Antares.  

Here are the images, with the zoom-out followed by the zoom-in.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   Despite both having a pale red appearance, remember that as a planet in our solar system, Mars is only about 187 million miles from us this evening, at just over 2 a.u.'s.  Antares, with a solar radii of about 2,700 as a huge, huge star, only appears as a small light, at a distance of 604 light years.  With a luminosity of over 387,000 "Suns", it is no surprise that at that distance, we still see it as well as we do.  Mars has crept up a little on its "twin", as it is now a little less than 4º apart.  As mentioned earlier in the week, different ecliptic latitudes will lead Mars a little further north of the star.  They are still a good pair to view with the eyes along, if you wait to view them long enough after dark.  Give the Sun a chance to get far enough below the horizon, and remember that twilight is slightly shorter each evening.  After Mars passes Antares, it will continue to move through the southern constellations.  However, since the Sun is gaining on it in declination, it also means that we see Mars very slightly higher in the sky each day as soon as we can see it.