Three colorful planets grace the sunset horizon this weekend, January 14 and 15. Look toward the southwest, about one hour after the Sun disappears, to see Mars, Venus, and Neptune twinkling in the twilight sky. Venus is that can’t-miss, brightest, golden-colored “star” shining about three fist-widths above the SW horizon; Mars is apparent as a distinctly reddish “star” about three finger-widths to the upper-left of Venus; Neptune, better seen through binoculars, is that much dimmer, blue-green “star” almost directly beneath Venus (Saturday and Sunday.) As the new week progresses, Neptune will appear to move quickly away from Venus, towards the horizon, while Venus will inch slightly closer to Mars.

While these planets may appear similar and close together, from our point-of-view, they are actually very distant and different worlds. Venus, our closest and similarly-sized neighbor, is a brutal world, with an extremely dense carbon dioxide atmosphere, temperatures peaking above 800F, and days that last longer than years. Mars, that rusty red planet “behind” us, is the second-smallest planet in the solar system, but it sports the largest volcano and the second-highest mountain. Temperatures range from -225F to the mid 90sF. The most distant of our three highlighted planets is Neptune, but it is also the largest. This gaseous ice-giant, which measures nearly eight times the “diameter” of Earth, is so distant that one trip around the Sun takes 164 years! It gets its unusual color from traces of methane in its upper atmosphere.

The graphic, below, illustrates the evening of Saturday, Jan 14, and includes an inset to help you find your way.

threeplanets

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