Double comet alert! Comets Lemmon and Comet Swan will be at their closest and brightest this week. Here’s how to tell them apart.

If you want to see two comets, your chance is early this week. After a year of no comets bright enough to be seen without specialized equipment, two comets appeared simultaneously: Comet C/2025 A6 (Lemon) and Comet C/2025 R2 (SWAN).

Comet Lemon may be more like Lyme than its name suggests, but on Tuesday (October 21), the dust-laden snowball from the outer solar system will make its closest approach to Earth and is likely to shine brightest. It has now reached a magnitude of 4.5, according to SpaceWeather.com. It is about the same brightness as the Spring Honeycomb Galaxy Cluster (M44) and only slightly fainter than the Andromeda Galaxy (M31).

While Comet Lemon is technically visible to the naked eye in very dark skies, you’ll need binoculars to catch a glimpse of another, fainter, icy visitor, Comet C/2025 R2 (SWAN). Remarkably, Comet Swan will make its closest approach to Earth on Monday (October 20), the day before Comet Lemmon, but it will be about three times as bright as Magnitude 5.9. (In astronomy, the higher the magnitude, the fainter the object.)

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The best time to see both comets at night this week will be about an hour and a half after sunset. You can check your local time on Timeanddate.com. On Monday, Comet Lemon will be visible in the northwest sky, near the Big Dipper and the bright star Arcturus, and near the horizon.

Follow the star shape of the Big Dipper’s handle to “arch toward Arcturus.” The comet will be about two-thirds of the way there. It will rise a bit more on Tuesday. For Comet Swan, look for the Summer Triangle of bright stars (Vega, Deneb, and Altair) in the southwest. Comet Swan can be found approximately midway between Altair and the horizon.

Helpful finder charts and sky maps for both comets are available at The Sky Live, In-The-Sky.org, Stellarium, and in night sky apps such as Sky Guide, Sky Tonight, and SkySafari 7 Pro. If you want to try your hand at comet photography, our guides can help.

The two comets are on completely different journeys. Comet Lemon is scheduled to come within 56 million miles (89 million kilometers) of Earth on Tuesday, Nov. 8, on its way around the sun in its 1,350-year orbit, Sky Live said. (However, according to StarWalk, Jupiter stole some of Comet Lemon’s orbital energy and shortened its period by nearly 200 years, so it won’t return until 3179.)

Comet Swan, a long-period comet that orbits the sun every 20,000 years, will blast off 24 million miles (39 million kilometers) from the inner solar system on Monday, according to Universe Today. This corresponds to about a quarter of the distance between the Earth and the Sun.