Tonight – April 19, 2018 – look for the moon and Winter Circle (or Winter Hexagon) stars. It’s difficult to convey the humongous size of the Circle, a great lasso of brilliant stars that fills our western sky at dusk and nightfall.
Look for a circular (or hexagonal) pattern of bright stars around the April 2 moon. Just be sure to look at nightfall, because the Winter Circle stars will sink below the horizon by early evening.
The Winter Circle can be seen from around the world, although its orientation with respect to the horizon will be different, depending on where you are.
No matter what part of Earth you’re standing on, though, this same pattern of bright stars will surround the moon on April 19.
If you’re in the Southern Hemisphere, notice the sky’s brightest star – Sirius – will appear at the top of the Circle and the star Capella at the bottom (if you can see Capella at all; it’s far to the north on the sky’s dome).
The Winter Circle stars are bright, but the brightest starlike object in the sky on these April 2017 evenings is the planet Jupiter. At nightfall on April 2, the moon and Winter Circle are in the west, while Jupiter shines in the opposite direction – east – and quite close the horizon after sunset. Earth is about to go between Jupiter and the sun, and so the planet is nearly at its brightest for this year. Jupiter’s yearly opposition will come on April 7.
Bottom line: Use the moon on April 19, 2018, to find the bright stars of the Winter Circle!