THE ANTI-TAIL OF COMET ZTF: Astrophotography alert! Comet ZTF (C/2022 E3) is developing an anti-tail, and tonight may be the best time to photograph it. Unlike ordinary comet tails, which are blown away from the sun by solar wind and radiation pressure, anti-tails point toward the sun. That sounds impossible, yet Bill Williams just photographed the anti-tail of Comet ZTF from his observatory in Chiefland, Florida:

"Comet ZTF has developed an anti-tail in addition to its dust and ion tails!" says Williams. "Just how many tails can a comet have?"

Briefly, three. Comets sometimes grow an ephemeral third tail, the "anti-tail." It's an optical illusion seen when Earth crosses a comet's orbital plane. At that moment, the edge of the comet's fan-shaped dust tail looks like an sunward pointing spike.

"It's happening tonight," says longtime comet observer Paul Robinson of Longmont, CO. "On the evening of Jan. 22nd in the Americas, Earth crosses the orbit of Comet ZTF, which should produce a good spike. Photographers will not want to miss this!"

Robinson has been tracking comets since Kohoutek in 1974. "I have seen and predicted several orbital crossings--including Comet PanSTARRS in 2013, which crossed on May 26th, my birthday. I saw a 7 degree sunward spike in 25x100 binoculars that day."

The iconic anti-tail of Comet Arend-Roland (C/1956 R1) in 1957.Credit: Palomar Observatory

"My estimates using Starry Night Pro 8 say that Comet ZTF's orbital crossing will take place at 11:30 pm EST on Jan. 22nd," notes Robinson. JPL's Horizons ephemeris suggests a slightly different time: 08:50 pm EST. The anti-tail should be sharp and bright throughout that time range.

Astrophotographers, point your optics here.

more images: from Miguel Claro of Alqueva, Portugal; from Dalibor Hanžl of Pavlovice, Czech Republic; from Jan Curtis of Oracle, Arizona; from Michael Jaeger of Weißenkirchen, Austria; from Ruslan Merzlyakov at National Park Thy, Denmark; from Alessandro Carrozzi of Fregenal de la Sierra, Spain; from Chris Schur of Payson, Arizona; from Silvana Diaz of Ezeiza, Argentina