Comet Lemmon 2025, Another Opportunity

[William Monfredo]

Look for it in the evening, low in the northwestern sky, with a close approach to earth on the 21st of October.
Diagram shows Comet Lemmon in Constellation Bootes then, hazily visible to the naked eye (Anthony Wood.)

If you have binoculars or a decent camera, check it out further. I'm going to go out and try, we'll see.
For more specifics, see Comet C/2025 A6 (Lemmon): Complete Information & Live Data | TheSkyLive .

 

[William Monfredo]

Moon phase on October 21, 2025 for Comet Lemmon observation: New moon, zero light interference.​

At the close approach, it will fly "only" 55 million miles away from earth, positioned as in this figure (ESA/NEOCC, The Watchers.)
Head for a dark, rural sky. Orionid meteors from Halley's Comet debris will also streak around on both the 20th & 21st of October.

 

[William Monfredo]

Actually rare…multiple comets in the sky at the same time!

You can see them in opposite sky locations. Whereas Comet Lemmon’s to the NW, less-bright Comet SWAN’s to the SW.

An optimal time to observe Comet Lemmon on Monday, Oct. 20 for example…
1 & 1/2 hours after sunset for about a 1/2 hour. It will appear to slowly descend toward the horizon as twilight progresses.
In New York, figure about 17 degrees above the horizon at first.

“Look for Comet Lemmon two-thirds of the way along a line between Alkaid — the bright star at the end of the Big Dipper’s handle —
and bright star Arcturus farther west (Forbes).

And Comet SWAN will appear blue-green (binoculars needed) low in the SW sky after the sun sets, too.

“...in the Constellation Sagittarius, above the famous “Teapot” asterism, but also below the bright star Altair in the Summer Triangle.
It lies in front of the Milky Way’s dense star fields, which will be visible behind the comet..." (Forbes.)
In New York, figure about 34 degrees above the horizon to start.

 

[James K]

If I remember (and its not cloudy) I'm gonna go out & see if I can see it. In westerly directions I'm looking away from city lights, may still be too much light in the air overall, but it costs no time or trouble to go effort to go outside & look. .lol.

Though I'm not sure how "1 & 1/2 hours after sunset" translates to here with that. (sunset here is 6:14 today...so if you have to take into account using eastern time of 6:14, with the 2-hour difference, it'd be 4:14 & still too light out. Is that right or do you go ~90min after your local sunset??)

 

[William Monfredo]

...go ~90min after your local sunset...

Yes, use your location and times. Quarter 'til eight or so for you...good luck!

 

[James K]

Thanks.. that timing will be perfect.
As long as I remember I plan to go up on the roof & look, since trees block my view from yard or deck. .lol.
Probably try tonight since there's a coldfront headed this way tomorrow...