COMET SEARCH

Crossing the plane

WE HAVE A MULTITUDE of 10th- to 11th-magnitude comets to choose from this month. The least erratic is 67P/ChuryumovGerasimenko. Approaching as close to us as Mars, it receives a modest cooking from the Sun’s rays, pouring out dust in a reasonably reliable way.

After midnight, find it following Aldebaran up the northeastern sky. On Oct. 8, it skims only 1° north of the Crab Nebula (M1). And your reward for waiting until moonset before dawn on the 16th is the comet posing with the splashy star cluster M35 in Gemini.

This snowball’s soft glow will need a 4-inch scope under dark skies. An 8-inch aperture reveals the well-defined bow shock on the eastern flank, where the solar wind pushes back the dust. At month’s end, Earth passes through the plane of the comet’s orbit, giving us an edge-on view and a good chance at seeing a weak anti-tail, where the dust and ion stream poke out the other side.

Also don’t miss 4P/Faye, cruising 8° to the south. It too gives us a plane crossing (on the 6th). About the same distance to Churyumov-Gerasimenko’s northeast, perhaps C/2019 L3 (ATLAS) will be acting up. Meanwhile, 6P/d’Arrest swipes past globular cluster M55 in Sagittarius midmonth, but this small comet will be a pale fuzz in comparison.

The rubber duck-shaped 67P/Churyumov-Gerasimenko, which the Rosetta mission orbited in 2015, is back. Alongside it are 4P/Faye to the south and C/2019 L3 (ATLAS, not shown) to the northeast.