Skywatchers are in for a treat this October as two comets,designated Lemmon and SWAN,are simultaneously visible from the Northern Hemisphere. These celestial visitors promise a breathtaking display, peaking in brightness around October 20-21, coinciding with the Orionid meteor shower. Astronomers anticipate the comets will be visible with binoculars, and under exceptionally dark skies, perhaps to the naked eye.

Comet Lemmon: A Rare Return

Of the two, Comet Lemmon is presently the brighter of the pair. This comet, officially known as C/2025 A6, last journeyed through the inner solar system approximately 1,350 years ago, and its next appearance isn’t predicted until around the year 3175. Its current proximity to Earth provides a unique viewing opportunity for observers.

Comet SWAN: A Newly Discovered Spectacle

Comet SWAN, or C/2025 R2, is a more recent discovery, spotted in September. Its orbital period is far longer than Lemmon’s-taking roughly 22,554 years to orbit the sun, with its next visit scheduled for 24,579. This makes it a truly remarkable sight for astronomers and casual observers alike. Both comets represent the first binocular-visible comets since the appearance of Comet Tsuchinshan-ATLAS in October 2024.

Viewing Guide: October 10, 2025

Locating Comet Lemmon

On the evening of October 10, 2025, Comet Lemmon will be visible in the northeastern sky before dawn. Look to the right of the Big Dipper constellation,relatively low on the horizon. Specifically,it will appear roughly halfway between the stars Dubhe and Merak,located on the outer edge of the Dipper’s bowl,near the shining star Regulus in Leo. According to observing charts from In-The-Sky.com, the comet will be approximately 78.3 million miles from the sun and 70.7 million miles from Earth.

Locating Comet SWAN

Comet SWAN, characterized by its bluish-green hue, can be spotted low in the southwestern

What specific atmospheric conditions might hinder the optimal viewing of comet C/2023 A3 (Tsuchinshan-ATLAS) during its peak visibility in late September – early October 2025?

Upcoming visibility of the Two Green Comets: Where and When You Can Witness Them

Understanding the Green Comets: C/2023 A3 (Tsuchinshan-ATLAS) and 13P/Olbers

2025 promises a spectacular celestial event: the simultaneous visibility of two green comets – C/2023 A3 (Tsuchinshan-ATLAS) and 13P/Olbers. Both comets exhibit a distinctive green hue due to the presence of diatomic carbon in their comas,which glows when exposed to ultraviolet radiation from the sun. While both are “green comets,” their trajectories, brightness, and optimal viewing times differ. This guide will provide everything you need to know to witness these stunning astronomical displays. Comet viewing, stargazing, and astrophotography enthusiasts are in for a treat!

Comet C/2023 A3 (Tsuchinshan-ATLAS): The Brighter of the Two

Discovered in early 2023, C/2023 A3 (Tsuchinshan-ATLAS) initially sparked excitement due to predictions of possibly exceptional brightness. While initial forecasts suggested it coudl become a naked-eye comet, current projections indicate it will likely require binoculars or a small telescope for optimal viewing.

* Peak Visibility: Late September – early October 2025.

* Best Viewing Location: Northern Hemisphere.The comet will pass closest to Earth during this period.

* Constellation: Initially in the constellation Camelopardalis, moving towards Ursa Minor.

* Brightness Estimate: Expected to reach around magnitude 5, potentially brighter under ideal dark sky conditions.

* Observing Challenges: The comet’s proximity to the sun during peak visibility may create a challenging observing environment due to twilight.

* Green Comet Color: The vibrant green color is caused by the release of diatomic carbon as the comet warms up.

Comet 13P/Olbers: A Periodic Visitor

Comet 13P/Olbers is a periodic comet, meaning it returns to the inner solar system on a predictable schedule (approximately 69 years). This comet is less radiant than C/2023 A3 but offers a more reliable viewing chance.

* Peak Visibility: Mid-october 2025.

* Best Viewing Location: Northern Hemisphere, especially mid-northern latitudes.

* Constellation: Will be visible in the constellation Virgo.

* Brightness Estimate: Expected to reach around magnitude 7,requiring binoculars or a small telescope.

* Observing Advantages: 13P/Olbers will be better positioned for viewing during darker hours, away from significant solar glare.

* Periodic Comet: Its predictable orbit makes it a favorite among comet observers.

Essential Equipment for Comet hunting

Successfully spotting these comets requires a bit of preparation. Here’s a checklist of recommended equipment:

1. Binoculars: 7×50 or 10×50 binoculars are ideal for locating and observing both comets.
2. Telescope: A small telescope (60-80mm aperture) will provide enhanced views, revealing more detail in the comas and tails.
3. Star Chart or Astronomy App: Essential for identifying the comets’ positions and navigating the night sky. popular apps include Stellarium, SkySafari, and star Walk.
4. Red Flashlight: preserves your night vision while consulting star charts or adjusting equipment.
5. Warm clothing: Even in October,nights can be cold,especially in rural areas with dark skies.
6. Dark Sky Location: Light pollution substantially hinders comet viewing. Seek out locations away from city lights.

Finding Dark Skies: Minimizing Light Pollution

Light pollution is the biggest enemy of comet observers. Here are some resources to help you find dark sky locations:

* Dark Site Finder: https://darksitefinder.com/maps/world.html

* International dark-Sky Association (IDA): https://www.darksky.org/ – Offers a directory of certified Dark Sky Parks and Sanctuaries.

* Light Pollution map: https://www.lightpollutionmap.info/

Observing Techniques: Maximizing Your Chances

* Acclimatize Your Eyes: Allow at least 20-30 minutes for your eyes to adjust to the darkness. Avoid looking at bright lights during this time.

* Use Averted Vision: Looking slightly away from the comet can make it easier to detect, as it stimulates more sensitive parts of your retina.

* Scan Slowly: Systematically scan the area of the sky where the comet is expected to be located.

* Patience is Key: Comet observing requires patience. Don’t be discouraged if you don’t spot it promptly.

* Astrophotography: For those interested in capturing images of the comets, a tracking mount and a DSLR or dedicated astronomy camera are recommended. Long exposure times are necessary to capture faint details.

Past Comet observations & Importance

Throughout history, comets have been viewed with a mixture of awe and fear.Halley’s Comet, perhaps the most famous periodic comet, has