Astro-Observer

Meteor showers

Monocerotid Meteor Shower

By Astro-Observer · Last reviewed November 8, 2026

Active
December 1 – December 19
Peak
Around December 8–9
Peak rate (ZHR)
3
Radiant
Monoceros (6h 40m, +8°)
Speed
41 km/s (medium)
Parent comet
C/1917 F1 (Mellish)
Best seen from
Both hemispheres
Best time
Late evening to dawn, best around 1 to 2 a.m.

Next peaks

Expected peak (UTC)Moon at peakMoonlight
December 9, 2026, around 10h New Moon, 0% lit Little or none
December 9, 2027, around 17h Waxing gibbous, 82% lit Bright Moon

Computed from the shower's peak solar longitude (λ☉ 257°). Real peaks can come a few hours early or late, and you will see meteors on the nights either side. The peak hour may be in daylight where you are; watch the darkest hours of the nearest night.

The Monocerotids, also called the December Monocerotids, are a weak shower that shares the sky with the much stronger Geminids. Their radiant is in the dim constellation Monoceros, the Unicorn, between Orion and Canis Minor. Even at the peak you will see only a few an hour.

Where the meteors come from

The parent is thought to be Comet C/1917 F1 (Mellish), which takes about 143 years to orbit the Sun and was last near the Sun in 1917. A study of video meteor orbits found that both the Monocerotids and the November Orionids may come from this comet, with the Monocerotid stream perhaps the younger of the two.

When to watch

The shower is active from December 1 to 19. Visual counts usually peak around December 9 (see the table above for the Moon). Video cameras, though, show a narrow peak near December 14 with a ZHR of about 8, at the Geminid maximum, which IMO says still needs explaining. The radiant is highest at about 1:30 a.m.

How to find the radiant

Monoceros has no bright stars. The radiant lies roughly between Orion's Betelgeuse and the bright star Procyon, and about 8 degrees south of Alhena at the feet of Gemini. It rises in the east in the evening and is well up in the south after midnight (in the north from the Southern Hemisphere).

What to expect

Expect one or two Monocerotids an hour from a dark site, and perhaps none from the suburbs. They are medium-speed meteors at 41 km/s, and with a population index of 3.0 most are faint.

Viewing tips

  • Watch on a Geminid night and count any Monocerotids as a bonus.
  • Pick a field where the two radiants do not line up: IMO suggests north of Taurus in the evening or near Leo in the morning.
  • Trace each meteor back. A Monocerotid points between Betelgeuse and Procyon, not to Castor.
  • Watch for at least an hour around 1 to 2 a.m., when the radiant is highest.

History and notable displays

IMO calls the shower long known but too poorly observed to study in detail. In 2011 Peter Vereš, Leonard Kornoš and Juraj Tóth used video orbits from the SonotaCo database to support the link with Comet Mellish. The Monocerotids are a minor shower mainly followed by experienced observers and video networks.

About the numbers. The ZHR (zenithal hourly rate) is how many meteors one observer would see in an hour under a perfectly dark sky with the radiant straight overhead. Real counts are almost always lower: under suburban skies, or with the radiant low, expect a half to a quarter of it, or less.

Sources

Checked November 8, 2026.