There is a small, untidy visitor in the evening sky this week, one that does not keep to schedules or respect expectations. Comet C/2025 R3 Pan-STARRS has come south, slipping out from the Sun’s glare after a close encounter late in April, and is now climbing into view for those of us with a clear western horizon. I managed to spot it last week, or at least my camera did. Light from the full Moon washed the sky pale, and the comet itself was invisible to the naked eye, but a short exposure revealed a tail stretching more than two degrees across the frame. This week should be different. That’s because the Moon rises after the comet has set, leaving a darker sky and a better chance of seeing it directly, especially with binoculars. As the comet orbits the sun, its position changes from night to night. You will find it drifting through Orion. The comet will not leap out at you. It will sit there, a faint smudge at first glance, but with a little patience, it resolves into something more.…