An aperitif is an alcoholic drink you take before a meal to stimulate the appetite. Tonight, a close conjunction of Venus and the star Regulus offers a visual aperitif for tomorrow morning’s occultation / close conjunction of the waning crescent moon and Aldebaran. You’ll find the pair — along with Mercury — low in the western sky in mid-twilight. First find Venus and then stare a little closer to see the star Regulus nearly caught up in the planet’s glare just 1° to its lower left (south).
Right now, the moon’s a crescent before sunrise, but it’s heading back into the evening sky very soon. When it does, watch for it to pass very close to Mercury and then Venus on July 14-15. We’ll have more details on what to expect closer to those dates.
If you live in the northern U.S., northern Europe and southern Canada, July’s the best month to watch for noctilucent clouds at dusk. They generally appear low in the north-northwestern sky when the first stars come out. While other clouds at this time appear as gray or silhouetted masses, noctilucent clouds glow pale blue. They’re Earth’s highest clouds, forming at 47-53 miles up or more than five times the altitude of typical high clouds like cirrus. At lower altitudes, water vapor condenses on sand, dirt, soot and salt to form clouds. With noctilucent clouds, dust from extinguished meteors provides the nuclei for water condensation, making them half terrestrial and half celestial!
If you spot them, try to get a photo with a camera on a tripod and short time exposure. It could be months or the next year when you see them again; night-shining clouds are still a rare sight from U.S. latitudes.