This month offers a great opportunity to see two of the heaven’s best-known, brightest, and ruddiest naked-eye objects—one being a planet and the other a star—placed near each other in the sky. Mars and Antares will be found facing south and southwest, respectively, in the evening twilight.
Mars is slowly retreating from its awesome closest approach in July (see that month’s Sky Talk) but is still a brilliant object near the southern meridian. To the west is radiant Antares. (Setting your rotating Star & Planet Locator for about 8 p.m. shows it in the constellation Scorpius—but not Saturn which is in Sagittarius. Since planets are continually on the move, they can’t be shown on a fixed star chart. For that reason, they are listed in a table on the reverse side of the chart, showing their positions in each month for the current year.)
Here are some interesting facts about this star and planet combo. The name “Antares” actually means “the rival of Mars.” And while currently, the two are about the same brightness, Antares is really redder than Mars (which is often called the “Red Planet” but is actually ruddy-orange to most eyes). Antares often flickers like a fire does due to atmospheric scintillation, especially being positioned so low in the sky. But Mars does not flicker. Stars twinkle because they are so far away that essentially a single ray of their light is reaching us and is easily affected by the atmosphere on its way to the eye. Planets, on the other hand, are relatively nearby and have sizeable disks, so that the bundle of rays coming from them average out the turbulence and cause them to shine with a steady light.
Other ruddy stars look fiery—especially when rising or setting low over the horizon— but none can match the fiery appearance of Antares. (As an aside, if you wear glasses and are near-sighted, take them off when viewing Antares and other bright stars near the horizon. This will greatly enhance the flickering you’ll see. The same goes if using binoculars—slightly de-focus them to see a celestial kaleidoscopic display!)
Two final thoughts. Antares is huge a supergiant sun big enough to engulf all of the inner planets including its namesake. Yes, that’s right. The Red Planet would be inside that fiery red star! And many find it hard to believe that stars actually have color, thinking that they all just shine with a silvery white light. But as stargazer J.D. Steele wrote in the late 1800’s, “Every tint that blooms in the flowers of Summer, flames out in the stars at night.” And the poet Longfellow referred to the stars as the flowery blossoms in the infinite meadows of heavens.
— James Mullaney
Former assistant editor at Sky & Telescope magazine & author of nine books on stargazing. His latest, Celebrating the Universe!, is available from HayHouse.com.