This month, sky-gazers are being treated to a rare celestial event as two newly discovered comets, Lemmon and SWAN, make their closest approaches to Earth, offering an unparalleled opportunity to witness these ancient “solar system time capsules” and learn more about our cosmic origins.
Prepare your binoculars and telescopes, fellow cosmic enthusiasts! October 2025 presents a unique and thrilling opportunity for both seasoned astronomers and casual sky-watchers alike. Two recently discovered comets, designated C/2025 A6 Lemmon and C/2025 R2 SWAN, are streaking across our skies, making their closest passes to Earth and offering a spectacular, albeit fleeting, display.
Comets, often referred to as “dirty snowballs,” are truly magnificent celestial bodies. They are primarily composed of ice, frozen gases, and rock. As these icy wanderers venture closer to stars like our Sun, the heat causes their frozen components to vaporize, releasing gas and dust into space. This process creates their iconic, luminous tails that stretch for millions of miles, a sight that has captivated humanity for millennia.
A Rare Glimpse: Comets Lemmon and SWAN Explained
The discovery timelines of these two comets highlight the ongoing vigilance of astronomical surveys. Comet Lemmon (C/2025 A6 Lemmon) was first identified on January 3, 2025, by the Mount Lemmon Observatory in Arizona. This discovery was part of the Catalina Sky Survey, a NASA-funded initiative primarily focused on detecting near-Earth objects that could pose a risk to our planet, as explained by Carson Fuls, director of the Catalina Sky Survey at the University of Arizona’s Lunar and Planetary Laboratory. Fuls noted that it wasn’t immediately clear it was a comet due to its initial dimness, unable to produce the dramatic tail seen today. However, it quickly became apparent that this was a significant find, potentially one of the best comets of the year for observers.
Comet SWAN (C/2025 R2 SWAN), on the other hand, was a more recent detection, first spotted on September 10, 2025, during its close approach to the Sun. Its discovery is attributed to Ukrainian amateur astronomer Vladimir Bezugly, who identified it through images from the Solar Wind ANisotropies (SWAN) instrument. This instrument is aboard the Solar and Heliospheric Observatory (SOHO) spacecraft, a collaborative project between NASA and the European Space Agency dedicated to studying our Sun. Qicheng Zhang, a postdoctoral fellow studying small body astronomy at Lowell Observatory, provided insights into these discovery dates.
What makes these comets particularly special for sky-gazers is their classification as long-period comets. They possess vast, oval-shaped orbits that take hundreds, or even thousands, of years to complete. This means their proximity to Earth is a truly limited-time event. Carrie Holt, a postdoctoral fellow and astronomer at Las Cumbres Observatory, underscores this rarity: Comet SWAN will not reappear for another 650 to 700 years, while Comet Lemmon will remain out of sight for an astonishing 1,300 years. This makes your chance to observe them now incredibly precious.
Solar System Time Capsules: Why These Comets Matter
Beyond their visual splendor, comets like Lemmon and SWAN offer an invaluable scientific window into the early days of our solar system. Astronomers are actively observing these bodies to unravel the mysteries of long-period comets, defined by orbits lasting 200 years or longer. These comets spend the vast majority of their existence at the frigid, distant edges of our solar system, residing in a vast, spherical shell of icy bodies known as the Oort Cloud, as described by NASA’s Jet Propulsion Laboratory. NASA explains that the Oort Cloud is the most distant region of our solar system, thought to be the source of many long-period comets.
Carrie Holt elaborates on their scientific significance, noting that these comets likely formed near gas giants such as Jupiter and Saturn. Billions of years ago, they received a gravitational “kick” that propelled them into the solar system’s far reaches, where they have been preserved in a deep freeze ever since. Holt explains: “When one gets nudged back toward the sun, we’re seeing materials that have barely changed since the solar system’s beginning. As their ices start to sublimate… we get a glimpse of the original building blocks of our solar system and a chance to learn how planetary systems like ours come together.” In essence, these comets are pristine time capsules, holding clues to the very formation of planets.
Comet Double Feature: What to Expect
The close approaches of Lemmon and SWAN are staggered by just one day, making this a truly remarkable double feature for astronomers globally. Comet SWAN will make its closest approach to Earth on October 20, coming within 24 million miles (38.6 million kilometers). The very next day, October 21, Comet Lemmon will swing by our planet at a distance of 55 million miles (88.5 million kilometers), according to Quanzhi Ye, an associate research scientist at the University of Maryland.
Visually, both comets share striking similarities in images: they are often enveloped by a distinctive green gas and boast prominent, long tails streaming behind them, as described by Zhang. Their visibility windows, however, differ slightly, adding a layer of planning for dedicated observers.
- Comet SWAN: Primarily observable in the early evenings, right after the sky darkens. It favors sky-gazers in the Southern Hemisphere but is becoming increasingly visible in the Northern Hemisphere. Expect it to fade rapidly soon, so catch it while you can.
- Comet Lemmon: Currently visible right before sunrise, it will soon transition to being visible only in the evenings. It is mainly visible to those in the Northern Hemisphere but is also becoming visible in the Southern Hemisphere. This comet is expected to brighten further in the coming weeks through early November, making it an excellent target for observation. However, it will subsequently hide behind the Sun in November and December, becoming visible exclusively to Southern Hemisphere observers thereafter.
Ye points out that because both comets appear relatively near the Sun from Earth’s perspective, there is only a short window each day to successfully observe them. Despite this, Carson Fuls enthusiastically suggests that Lemmon might be “one of the best comets of the year for observers” due to its potential brightness. Fuls states, “This one is spectacular because it may be able to be seen from a dark location with only a regular set of binoculars or even the naked eye at its brightest.” Zhang adds that Lemmon is rapidly brightening and should become at least faintly visible to the naked eye in the coming weeks.
Your Essential Guide to Spotting the Comets
Observing these rare celestial visitors requires a bit of preparation and the right tools. Here’s how you can make the most of this extraordinary opportunity:
Optimal Viewing Conditions and Equipment
- Binoculars or Telescopes: While Lemmon might become faintly visible to the naked eye at its brightest, both comets are best viewed with binoculars or a small telescope. This will enhance their visibility and allow you to appreciate their tails and green glow.
- Dark Skies: Carrie Holt strongly recommends observing from a dark area, far away from city light pollution. Light pollution significantly reduces the visibility of faint celestial objects.
- Timing: Pay close attention to the specific windows for each comet: SWAN in early evenings (just after dark) and Lemmon shifting from pre-sunrise to evenings. The week around their closest approaches (October 20-21) will be prime viewing time, especially since the Moon will be “out of the way,” providing darker skies. A small telescope will extend this viewing period beyond a week.
Utilizing Technology for Tracking
- Planetarium Software: Free planetarium software such as Stellarium or KStars can be invaluable. Qicheng Zhang notes that these programs show the exact real-time positions of comets relative to stars, making them easy to locate in the night sky.
- Mobile Apps: A multitude of astronomy apps are available that can show where the comets are in real time on your smartphone or tablet. These apps often feature augmented reality modes to help you point your device at the sky to find objects.
- Phone Camera Technique: For an experimental approach, Holt suggests using your phone camera. “By changing the settings to a longer exposure of a few seconds and aim it at the sky,” you might be able to capture a faint image.
- Current Position (Lemmon): Teddy Kareta, an assistant professor at Villanova University, notes that Comet Lemmon is currently located “a bit below the bottom of the Big Dipper.”
Online Observation Opportunities
If local skies are uncooperative due to weather or light pollution, you don’t have to miss out. On the evening of October 20, the Virtual Telescope Project will be hosting a live stream. This online event will broadcast views of both comets from telescopes situated under dark skies in Manciano, Italy, bringing the spectacle directly to your screen.
These dual comet flybys are a testament to the dynamic nature of our solar system and a thrilling reminder of the vast, unexplored cosmos. Don’t miss this chance to connect with the ancient building blocks of our planetary home. For more details on these celestial events, you can refer to the comprehensive report from AOL.
