Tuesday October 25, 2016; 11:18 pm EDT
Running from the Red Planet
Mars still lights up the night
Thursday’s first-quarter moon appears high in the southwest at sunset and sets in the west around 1am. Each following night, darkness finds the waxing gibbous moon a dozen degrees farther east, providing almost an hour of additional moonlight.
Friday, the moon is 15 degrees to the right of Mars, but come Saturday the two are practically on top of one another, separated by only two degrees. The red planet is just to the upper right of the moon as darkness falls, and they stay quite tight until setting around 2am. At -0.8 magnitude, Mars outshines any star — only Sirius is brighter, and the Dog Star is gone from view for the season.
Two months ago Mars was even brighter, as the planet was at opposition from the sun with earth directly between the two. Imagine opposition as if you were seated at the movie theater, the light from the projector streaming from behind you to the screen. The screen itself isn’t illuminated, but instead it reflects the projected light back to your eyes. As you turn your gaze from straight ahead, or if you shifted the projector, the reflected image grows dimmer. That’s what’s happening now, as earth’s faster orbit hustles it away from Mars, diminishing the angle of reflected light.
To see a simulation of the intricate dance between earth and Mars as they travel around the sun, go to http://tinyurl.com/9dtvspa.
Sunday the moon has another partner, the first-magnitude star Spica. The brightest star in the constellation Virgo, Spica is just a couple degrees to the moon’s right. A dozen degrees to the west of the pair is Mars, while a dozen degrees to their east is Saturn.
Monday the moon shines 10 degrees to the right of Saturn, while Tuesday it is five degrees to the left of the ringed planet.
As the sun sets Wednesday, the moon appears low in the southeast. Just a few degrees below the nearly full moon is the first-magnitude red-giant Antares, the heart of Scorpius the scorpion. Antares means literally the opposite, or rival, of Mars, because of its own reddish hue. Compare the two for yourself.