Tonight – August 1, 2018 – or any night in the coming month or two, you can rely on the Big Dipper to star-hop to the bright stars Arcturus and Spica. Just follow the arc to Arcturus, and drive a spike to Spica.
Every year, as late summer and autumn comes to the Northern Hemisphere, the Big Dipper is found fairly high up in the northwest sky at nightfall. From the Northern Hemisphere tropics, the Big Dipper sits lower in the sky as darkness falls, and then swings beneath the horizon relatively early in the evening. But, from middle-to-far northern latitudes, the Big Dipper prevails in the August evening sky.
Meanwhile, the Big Dipper isn’t visible from far southerly latitudes in the Southern Hemisphere at nightfall, because it’s below the horizon from that part of the world.
In August 2018, you don’t necessarily need the Big Dipper to find Spica at nightfall and early evening. Just look westward as darkness falls and you can’t miss the dazzling planet Venus – the brightest starlike object in the evening sky. Then note the king planet Jupiter, which – from northerly latitudes – is found in the southwest sky at nightfall (or from the Southern Hemisphere, Jupiter appears close to overhead as darkness falls).
All month long, look for Spica in between Venus and Jupiter. Although Spica ranks as 1st-magnitude star, it’s nowhere as brilliant as Venus or Jupiter. Day by day, watch for Venus to move closer and closer to Spica on the sky’s dome. By September 1, 2018, Venus and Spica will actually be in conjunction.
The Big Dipper may not be visible from the Southern Hemisphere, but it’ll actually be easier to view Venus and Spica from southerly latitudes. That’s because Venus and Spica stay out longer after sunset than they do in the Northern Hemisphere.
Arcturus should be fairly easy to view from the Southern Hemisphere as well. Look for this brilliant yellow-orange star in your northwest sky at nightfall and early evening.
Click here to find out when the sun, Venus, Spica and Arcturus set in your sky.
Bottom line: At this time of year, the Big Dipper is not visible from the Southern Hemisphere at nightfall. But as darkness falls in the Northern Hemisphere, you can use the Big Dipper to arc to Arcturus and to spike Spica.