Comet Lemmon streaking through the sky on September 23.
Courtesy of NASA
A comet that was discovered in January will make its closest approach to Earth on Tuesday. If you don’t see it this time around, the only way to see it again is with the help of time travel because it won’t be back until the year 3175.
Will the weather this week allow you to see Comet Lemon?
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The best viewing time will be after sunset
The Mount Lemmon Survey is an astronomical survey that employs a large telescope atop Mount Lemmon, near Tucson, Ariz. The MLS is part of the bigger Catalina Sky Survey, an attempt to identify objects that have a risk of impacting Earth. The 60-inch Cassegrain reflector telescope, equipped with a large, high-resolution camera, caught the first glimpse of the Lemmon Comet on Jan. 3 of this year.
The Catalina Sky Survey is using these two telescopes sitting atop Mount Lemmon in Arizona.
Courtesy of Catalina Sky Survey
The cosmic snowball, made up of frozen gases, dust and rock, is hurling past Earth at around 135,000 mph. Its orbital period — the time it takes to complete one orbit around the Sun — is around 1,350 years, but the gigantic star’s gravity will reduce that to 1,150 years; hence, the next chance to get a glimpse of the comet will be in 3175.
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“The comet will round the Sun on Nov. 8, but first it will pass its nearest to the Earth — at about half the Earth-Sun distance — on Oct. 21,” according to NASA. “Although the brightnesses of comets are notoriously hard to predict, optimistic estimates have Comet Lemmon then becoming visible to the unaided eye. The comet should be best seen in predawn skies until mid-October, when it also becomes visible in evening skies.”
The location of Comet Lemmon (C/2025 A6) on October 21 at 7 pm
Courtesy of St. Louis Science Center
Find a spot with minimal light pollution and a clear view of the western-northwestern horizon. The best viewing will be around 30 to 60 minutes after sunset, when the comet will be above the horizon. There is still a chance to see it with the naked eye, but a pair of binoculars or a small telescope will give you the best advantage to see this rare sight.
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“To spot the comet on Oct. 21, start by finding the Big Dipper in Ursa Major,” the Saint Louis Science Center advises. “Locate the handle of the Big Dipper and follow the direction it points to the west. This will direct you to the bright star Arcturus in the constellation Boötes. Looking east from Arcturus, the next bright stars you see are Epsilon, Sigma and Rho Boötis. C/2025 A6 (Lemmon) will be found just below these stars.”
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Now is the time to try to get a look at Lemmon. After early November, it will become more difficult to see the comet because it will dip lower closer to the horizon as it sinks lower in the evening sky. There will also be interference with the twilight glow after sunset.
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Will this week’s weather comply with comet viewing?
Clouds and showers tonight should obstruct the view of Comet Lemmon. Skies should start off mainly clear around sunset on Tuesday, but then increase overnight. So there should be at least a limited opportunity to get a look at Lemmon tomorrow night. Skies should be partially clear on Wednesday, Thursday and Friday evening, allowing for more opportunities to get a glimpse.
Sky cover forecast from early Tuesday morning into Wednesday night.
Courtesy of National Weather Service
The National Weather Service’s hourly sky cover forecast offers some hope that there could be a window of opportunity on Tuesday or Wednesday evening to see the comet. The forecast is calling for the sky to be about 50% covered by clouds on Tuesday evening, and just under 60% Wednesday evening. Certainly not ideal viewing conditions, but there could be enough breaks to get a peek. Friday, Saturday and Sunday evening aren’t expected to feature clear skies either, but there might be enough clearing during prime viewing time to get a glimpse of Lemmon.
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The National Blend of Models’ daily high and low temperature forecast.
Courtesy of WeatherBELL Analytics
After highs in the lower 60s today and tomorrow, a cold front sweeping through late Tuesday into early Wednesday will usher in colder Canadian air to close out the week. The National Blend of Models’ long-range forecast actually suggests 50s for highs from Thursday through the middle of next week. After the front brings some rain late Tuesday into early Wednesday, the rest of the week and this weekend should be relatively dry.
The Capital Region and Hudson Valley’s week ahead
Monday
Capital Region: Cloudy, on and off showers, possible thunderstorm, high in the middle 60s
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Hudson Valley: Showers likely, a bit breezy, high in the middle 60s
Monday night
Capital Region: Mostly cloudy, showers mainly early, low in the middle 40s
Hudson Valley: Scattered evening showers, partly to mostly cloudy, low in the lower to middle 40s
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Tuesday
Capital Region: Mostly sunny, high in the middle 60s
Hudson Valley: Sunny skies, high in the middle 60s
Tuesday night
Capital Region: Becoming mostly cloudy, showers late, low in the middle to upper 40s
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Hudson Valley: Becoming mostly cloudy, showers late, low in the middle to upper 40s
Wednesday
Capital Region: Showers early, then cloud and sun mix, high near 60
Hudson Valley: Showers mainly early, becoming partly sunny, high in the lower 60s
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Thursday
Capital Region: Partly to mostly cloudy, high in the upper 50s
Hudson Valley: Mostly sunny, high near 60
Friday
Capital Region: Partly to mostly cloudy, high in the middle to upper 50s
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Hudson Valley: Cloud and sun mix, high near 60
Saturday
Capital Region: Partly to mostly cloudy, high in the middle 50s
Hudson Valley: Increasing clouds, high in the middle to upper 50s
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Sunday
Capital Region: Partly sunny, cool, high in the lower 50s
Hudson Valley: Partly to mostly cloudy, high in the middle 50s
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