The Green Stellar Interloper

Comet Lulin may not be easy to spot, but it will be worth it

A thin, three-day-old crescent moon emerges from the sun’s glare low in the west Friday, with Venus less than two degrees away. The moon shines like the letter U with the evening star poised to its upper right. Even the afternoon sky cannot bleach out these two beacons in the west. As the sun sets, just before 6pm, look for them about 20 degrees above the western horizon. The two remain the brightest heavenly objects visible until setting just before 9pm.

Early mornings at week’s end Jupiter, Mercury and Mars crest the southeast horizon one after the other in a tight cluster with only a couple degrees between them. Day by day, Jupiter pulls away, rising a little higher before daybreak. At the same time, Mercury and Mars move closer together, until less than one-half degree separates the two before dawn Sunday and Monday.

A green, stellar interloper, discovered just two years ago at Taiwan’s Lulin Observatory, appears in the southeast with darkness. This fifth-magnitude comet, dubbed Lulin, straddles the line of naked-eye objects, so you’re best armed with binoculars or a small telescope to spot it. Friday is your best chance, as Comet Lulin has just passed it closest to earth and appears just a few degrees below bright Regulus, the heart of Leo the lion. After that, it moves away from any notable stars, growing dimmer night by night and fading from view. And unlike most comets, which orbit the sun and appear every so many years, astronomers have no indication that Lulin has ever visited our solar system before — or that it ever will again.