* Two comets, Lemmon and SWAN, are visible in the night sky through October 2025.
* Comet Lemmon will appear green and is best viewed in the northwest sky after sunset.
* Comet SWAN is dimmer and best viewed in the southwest sky, primarily from the Southern Hemisphere.
A once-in-a-lifetime cosmic treat for stargazers is on the celestial schedule this month, with two comets visible in the night sky through October 2025.
Comet Lemmon and Comet SWAN were visible beginning Oct. 20, just in time for the peak of the Orionid meteor shower. With the new moon falling on Oct. 21 and clear weather in Asheville, residents of Western North Carolina are in for a dazzling display.
Tonight's visible comets make a rare approach close to Earth, and both will peak in brightness between Oct. 20-21. The bright green Comet Lemmon (C/2025 A6) will pass by Earth within 56 million miles, while Comet Swan (C/2025 R2) will come even closer to Earth, at roughly 24 million miles, according to Space.com.
Here's what North Carolina stargazers should know about the two comets in October's night skies.
What is Comet Lemmon?
C/2025 A6 Lemmon or "Comet Lemmon" was first discovered in January 2025 by the Mount Lemmon Survey, which uses a 60-inch telescope at Mt. Lemmon, Arizona. It is known for appearing green in the night sky.
The ball of frozen gases speeds past the earth at 135,000 miles per hour, according to astronomy.com. The next time Comet Lemmon will make its closest approach is in about 1,150 years.
Where in the sky is Comet Lemmon visible?
Comet Lemmon is making a close approach on Oct. 21, 2025, during the new moon, and will brighten further near Halloween and through early November.
NASA says while it's tough to predict the brightness of comets, estimates say Lemmon will be best seen in the evening sky near bright stars like Arcturus in Boötes by looking northwest after sunset.
To spot it, first find when the sun sets at your location. Then, head out about 90 minutes after with a pair of binoculars or a telescope, and look toward the northwest. You'll notice each night it'll be making a climb northward.
What is Comet SWAN?
C/2025 R2 Swan, or "Comet SWAN," was first discovered in September 2025 by the Solar and Heliospheric Observatory's SWAN instrument. Twitter account Astronomy Picture of the Day (@apod) stated that an amateur astronomer discovered the "unexpectedly bright" comet in images of the SWAN instrument.
SWAN will reach only a quarter of the Earth-sun distance. Stargazers also watched for a SWAN-spawned meteor shower around Oct. 5 as Earth passed through the plane of the comet's orbit, according to NASA.
Where can Comet SWAN be seen?
Comet SWAN, or C/2025 R2 Swan, is also visible in the evening sky, but in the southwest. SWAN is slightly dimmer, although recent observations put it on a brightness magnitude of 5.6, meaning it may be visible to the naked eye as a very faint object in the dark night sky.
SWAN is best position for observers in the Southern Hemisphere, so it might be trickier to spot than Lemmon. On Oct. 16, SWAN was positioned about 5 degrees to the upper left of the star Xi Serpentis, in the eastern section of the constellation Serpens.
To spot it, look in the hours following sunset, before it sinks low on the south-southwest horizon. Use a stargazing app, like Stellarium, to find the comet.
What's the best time to see Comet SWAN? Comet Lemmon?
Comet Lemmon and Comet SWAN are both expected to shine the brightest around Oct. 31-Nov. 2, according to Starwalk.
Beginning Oct. 20, skywatchers can best find SWAN and Lemmon in the night sky during the darkest hours. Find a spot with a good view of the horizon away from city lights.
Lower magnification on any viewing equipment works best, as comets often have diffuse comas and long, faint tails that can span a significant portion of the sky.
What comet is visible tonight?
Both comets became visible during mid-October and will remain visible until early November.
Lemmon has reached a magnitude +6 on the detection limit of the human eye, which technically means it could be seen without a telescope or binoculars, if the sky is perfectly dark.
When will Halley's Comet appear next?
All this comet talk has stirred interest in Halley's Comet, the most famous of all comets that appears twice in a human lifetime.
Halley's Comet is expected to appear again around July 28, 2061, according to Space.com. Right now, Comet 1P/Halley is in the constellation of Hydra, known as the "female water snake" constellation, close to the celestial equator.
When did Halley's Comet last appear?
Halley's Comet last appeared in February 1986, although it was the worst possible viewing circumstances for Earth observers, being that it was out of sight and on the opposite side of the midwinter sun. However, midsummer 2061 promises a much better view - at least 10 times brighter, Space.com says.
Will the weather be clear enough to see Comet Lemmon? Comet SWAN?
While we're still too far out to know exactly what the weather will hold during peak dates for the two comets, Asheville and Western North Carolina weather during the week of Oct. 20 looks largely ideal for viewing astronomical phenomena:
Tuesday, Oct. 21 - Mostly sunny, with a high near 75. West wind 8 to 11 mph, with gusts as high as 18 mph. Overnight, mostly clear, with a low around 41. Northwest wind around 7 mph becoming west southwest after midnight.
Wednesday, Oct. 22 - Sunny, with a high near 64. Northwest wind 9 to 16 mph, with gusts as high as 23 mph. Overnight, mostly clear, with a low around 40. Northwest wind 6 to 9 mph, with gusts as high as 18 mph.
Thursday, Oct. 23 - Sunny, with a high near 67. West northwest wind 6 to 15 mph, with gusts as high as 23 mph. Overnight, mostly clear, with a low around 35.
Friday, Oct. 24 - Mostly sunny, with a high near 66. Overnight, partly cloudy, with a low around 41.
Saturday, Oct. 25 - Mostly sunny, with a high near 68. Overnight, mostly cloudy, with a low around 43.
Sunday, Oct. 26 - Mostly cloudy, with a high near 64. Overnight, mostly cloudy, with a low around 47.
Oct. 21 is a new moon. On Oct. 31, the beginning of peak dates, the moon will be in the waxing gibbous phase.
Iris Seaton is the trending news reporter for the Asheville Citizen Times, part of the USA TODAY Network. Reach her at [email protected].
Lori Comstock, USA TODAY NETWORK, contributed to this report.