Two Comets Visible Together Today: How to Watch Online

Comet 168P/Hergenrother
This Comet 168P/Hergenrother photo was taken Oct. 21, 2012, by Slooh member "Dave Lrkn." (Image credit: Slooh Space Camera)

Two comets are passing through the inner solar system and you can see both cosmic wanderers in the same telescope view today (Oct. 23) in a rare celestial treat.

The two icy wanderers are comet 168P/Hergenrother, which has been going through some major outbursts in recent weeks, and comet C/2012 J1 (Catalina), which won't pass through the inner solar system again for the next 200 years. By a fluke of celestial mechanics, the two comets can be seen in the same telescope view, setting the stage for today's online sky show.

A side-by-side view of comets 168P/Hergenrother and C/2012 J1 (Catalina) as seen by robotic telescopes operated by the Slooh Space Camera. (Image credit: Slooh Space Camera)

The online Slooh Space Camera will provide a free live stream of comets 168P/Hergenrother and C/2012 J1 (Catalina) through its robotic telescopes during a 30-minute sky show that begins at 5 p.m. EDT (2100 GMT).

"It’s comet fiesta time for astronomers — and the public," said astronomer Bob Berman, a Slooh commentator with Astronomy Magazine. "Here, Slooh will simultaneously watch two comets as they dramatically zoom in opposite directions in the same field of view!"

Slooh president Patrick Paolucci and outreach coordinator Paul Cox will also participate in today's webcast.

You can watch the comet webcast live on Slooh's website here:

It will also be carried on this page at the event's start time.

Adam Block at the Mount Lemmon SkyCenter in Arizona caught Comet 168P Hergenrother on October 5, 2012. (Image credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona)

Comet C/2012 J1 (Catalina) is a more recent celestial discovery. Astronomer A.R, Gibbs spotted the comet as part of the ongoing Catalina Sky Survey on May 13 of this year. Unlike 168P/Hergenrother, comet C/2012 J1 (Catalina) is a stable target that is gradually brightening as it makes its way toward its closest approach to the sun on Dec. 7. It is known as a "hyperbolic comet" and will not pass through the inner solar system for another 200 years, Slooh officials said.

Today, two comets will appear within 43.5 arc minutes of each other. There are 60 arc minutes in one degree used to measure object locations in the night sky. Your closed fist held out at arm's length can cover about 10 degrees of the sky.

Slooh officials said members of the website have been using Slooh telescopes to track the two comets regularly in recent days. The celestial line-up that places both comets in the same telescope field of view was first identified by Slooh member Maynard Pittendreig, officials said.

Editor's Note: If you snap an amazing photo of comets 168P/Hergenrother, C/2012 J1 (Catalina) or any other skywatching target, and would like to share it for a possible story or image gallery, send images, comments and location info to managing editor Tariq Malik at

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Tariq Malik

Tariq is the Editor-in-Chief of and joined the team in 2001, first as an intern and staff writer, and later as an editor. He covers human spaceflight, exploration and space science, as well as skywatching and entertainment. He became's Managing Editor in 2009 and Editor-in-Chief in 2019. Before joining, Tariq was a staff reporter for The Los Angeles Times covering education and city beats in La Habra, Fullerton and Huntington Beach. In October 2022, Tariq received the Harry Kolcum Award for excellence in space reporting from the National Space Club Florida Committee. He is also an Eagle Scout (yes, he has the Space Exploration merit badge) and went to Space Camp four times as a kid and a fifth time as an adult. He has journalism degrees from the University of Southern California and New York University. You can find Tariq at and as the co-host to the This Week In Space podcast with space historian Rod Pyle on the TWiT network. To see his latest project, you can follow Tariq on Twitter @tariqjmalik.