At mid-northern latitudes, Arcturus sets about 2 hours after sunset around Halloween, at the same point on the horizon as the summer sun. It’s a Halloween ghost of the summer sun and an echo of long summer afternoons.
This beloved Summer Triangle star is shifting westward in our sky. Its transit at nightfall in mid-October is a hallmark of the year, marking a shift toward winter – or summer – on your half of the globe.
At an equinox, and for several days before and after, the midday sun is straight up at noon seen from Earth’s equator. At this equinox, the sun is crossing the celestial equator, moving from north to south.