Tonight – February 20, 2016 – the almost-full waxing gibbous moon puts the constellation Cancer in the spotlight – but out of view. Demure Cancer the Crab is the faintest constellation of the Zodiac. You can see it only on dark, moonless nights.
The starry sky is like a great big connect-the-dots book, enabling stargazers to star-hop from brighter stars to more obscure nighttime treasures. For instance, when the moon drops out of the evening sky by the month’s end, you can look for Cancer the Crab to show its delicate starlit figure in the region of sky in between the Leo star Regulus and the Gemini stars Castor and Pollux.
This year, in 2016, we can use the dazzling planet Jupiter and Regulus, the constellation Leo’s brightest star, to locate the constellation Cancer, too. Jupiter appears over the eastern horizon by early evening in late February, nightfall in early March and dusk in late March.
Our feature chart at top shows the moon and Cancer for North American mid-northern latitudes. At nightfall, at mid-northern latitudes from around the world, the stars and planets are similarly positioned. As seen from Europe and Asia, though, tonight’s moon (on February 20, 2016) shines closer to Gemini’s stars, Castor and Pollux, and farther away from Regulus, the brightest star in the constellation Leo the Lion. This difference in the moon’s position, relative to the backdrop stars of the Zodiac, is due to the moon’s own motion in orbit around Earth.
From the Southern Hemisphere, the differences are due in part to the moon’s movement, and in part to the difference in perspective from one hemisphere to the other. Still, we all live under the same sky, and no matter where you live worldwide, the moon beams in front of Cancer tonight, with Castor, Pollux, and Regulus nearby.
Just remember – although we outline Cancer for you on our chart, you’re not likely to see this constellation in tonight’s drenching moonlight. Notice the stars around it, and come back in a week or so to find the faint Crab when the moon has moved on its way – and left the evening sky dark for stargazing.
Bottom line: The almost-full moon puts the constellation Cancer the Crab in the spotlight – but out of view – on the night of February 20.