Tonight or on your first clear night, face south between 8:30 and 9:00 PM. You’ll see a striking triangle. Three bright stars. You can’t miss it. Then from September 7 to 9, 2016, the triangle is near the Moon.
This picturesque triangle near the Moon is created by Saturn, Mars and Antares–and will stay out until late evening. Rarely is astronomy this easy.
The leftmost star is the brightest, with an obvious orange color. This is the planet Mars. It came closest to us in May and is still very bright. But it’s fading rapidly, and will keep dimming steadily throughout the fall and winter. Don’t bother pointing a telescope its way. Its disk is currently too small to show any detail. Just check it out with the naked eye, that’s plenty good enough.
To the right of Mars is another orange star. This one’s a real star, the famous Antares, the “alpha” member of Scorpius the scorpion. It may be the largest bright star in the heavens, though that honor probably belongs to Orion’s Betelgeuse. Legend has it that the hunter killed the scorpion and then the gods mercifully decided to keep them forever separated. Thus the two constellations are never visible at the same time; they’re on opposites sides of the firmament.
To visualize the size of either Betelgeuse or Antares, try a scale model. If our planet Earth is the period at the end of this sentence, then Antares is a ball as tall as a 14 story building.
The final star in the triangle, the topmost one, is the planet Saturn. This is where to point your telescope. It is certainly among the five best celestial splendors. This year the rings are angled in a wide open position, farthest from edgewise. Their orientation is perfect and Saturn is glorious. The only trick is that to see all the juicy detail like the inky black separation between its wider B ring and its darker and narrower A ring, requires steady air when stars aren’t twinkling.
Night after night the triangle changes shape, as Mars speeds to the left against the background stars. This is its actual eastward orbital motion at 15 miles per second. It’s stretching out the triangle like pizza cheese, and by mid-month this gorgeous in-your-face show will be over for keeps.