Bright Interlopers

Most of what we see in the night sky is neat and orderly. We know exactly where the stars and planets will appear centuries in advance. We know when eclipses will occur, and where best to view them. And we can spool out the phases of the Moon far into the future.

Yet the night sky still offers some unpredictable treats. In fact, two are coming up this year — we think.

Both of them are comets — big balls of rock and ice that sprout long, glowing tails when they get close to the Sun. One is scheduled to put on its best showing in the early evening skies of mid-March, when it’s expected to be bright enough to see with the unaided eye. The other will be at its best in November. But if early predictions are correct, it could be the brightest comet in centuries — perhaps shining bright enough to see during the day.

Both comets were discovered just last year. And both are probably making their first close approach to the Sun. Their paths indicate they’re heading inward from the far edge of