Tonight’s waxing gibbous moon – February 24, 2018 – shines inside a large asterism that we in the Northern Hemisphere often call the Winter Circle. It’s an incredibly large star configuration made of brilliant winter stars. Around the world on this night, the moon is inside the Circle. From anywhere in the Northern Hemisphere, look for the Winter Circle to fill up much of the eastern half of sky at nightfall. By mid-evening, the Winter Circle will swing to your southern sky, and then it will drift into the western sky around midnight.
If you’re in the Southern Hemisphere … although it’s not winter for you, these same stars appear around the moon. But it’ll appear “upside-down” with the star Sirius at top, instead of at bottom.
The Winter Circle – sometimes called the Winter Hexagon – is not one of the 88 recognized constellations. Rather, it’s an asterism – a pattern of stars that’s fairly easy to recognize. Our sky chart cannot adequately convey the Winter Circle’s humongous size! It dwarfs the constellation Orion the Hunter, which is a rather large constellation, occupying the southwestern part of the Winter Circle pattern.
Here’s how to locate the Winter Circle from mid-northern latitudes. At nightfall and early evening, look high overhead for the bright star Capella. This star marks the top (or more properly, the northern terminus) of the Winter Circle.
As Capella shines way overhead, the constellation Orion the Hunter is prowling in the southern sky. Draw a line downward through Orion’s Belt to find Sirius, the brightest star in the night sky. This star marks the bottom (the southern tip) of the Winter Circle.
Click on this sky chart if you want to connect the Winter Circle stars.
By the way, tonight’s waxing gibbous moon shows you where the sun resides in front of the backdrop stars in late June or early July. So enjoy the Winter Circle. And contemplate the sun being in this part of the sky when summer returns to the Northern Hemisphere!
Bottom line: On the evening of February 24, 2018, the waxing gibbous moon shines inside the huge pattern of stars known as the Winter Circle. Be sure to notice the different colors of these stars!