Monoceros
What is Monoceros?
Constellations· Winter evenings (N) · centre of the Winter Triangle. The unicorn galloping through the Milky Way at the centre of the Winter Triangle. Faint stars, but a treasury of winter nebulae and clusters: the Rosette, the Christmas Tree Cluster with the Cone Nebula, Hubble's Variable Nebula. Beta is a celebrated triple star. Look inside the Winter Triangle in the Sky view.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Monoceros is in your sky right now: https://nowsky.org/solar/sky?sel=con:Monoceros — location and time set automatically, no login.
Stars of the figure
| Star | Magnitude |
|---|---|
| Beta Monocerotis | 3.7 |
| Alpha Monocerotis | 3.9 |
The 2 brightest of the 3 stars used in the figure (2 lines). Lower magnitude means brighter.
Deep-sky objects near this constellation
Constellation basics
| Season | winter evenings (N) |
|---|---|
| Brightest star | Beta Monocerotis (3.7, triple) |
| How to find | inside the Betelgeuse–Sirius–Procyon triangle |
| Area rank | 88 |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Frequently asked
- When can I see Monoceros?
- winter evenings (N).
- How do I find Monoceros?
- inside the Betelgeuse–Sirius–Procyon triangle.
- What is the brightest star in Monoceros?
- Beta Monocerotis, magnitude 3.7.
- Where is Monoceros in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
The light echo of 2002 — V838 Monocerotis
In January 2002 an unnamed star in Monoceros suddenly swelled to 600,000 times the Sun's brightness. Named V838 Monocerotis, it behaved unlike a nova: its surface cooled and reddened, and instead of returning to normal months later it remained a huge star more than 1,000 solar diameters across. The leading explanation now is an outburst caused by two stars merging.
What made the event famous was the aftermath. The flash lit up, one after another, the shells of dust that had long surrounded the star, spreading outward, and from 2002 over several years Hubble recorded this light echo in a sequence of images as the light swept across the dust. The dust did not move; the place the light was passing did — a rare record in which the speed of light was captured on a scale the eye can see.
The constellation in depth
Monoceros was created by Plancius in 1612 in the Milky Way zone between Orion, Canis Major and Canis Minor. It has no classical myth; it depicts the legendary unicorn, reportedly inspired by the horned beast mentioned in Bible translations. With no bright stars, this patch of sky went nameless for centuries.
The objects outshine the stars. The Rosette Nebula is an emission cloud 130 light-years across with the open cluster NGC 2244 set at its heart like stamens; NGC 2264, the Christmas Tree Cluster, comes paired with the Cone Nebula. Hubble's Variable Nebula NGC 2261 is a rare reflection nebula that changes shape within days, and Plaskett's Star, a binary of more than 50 solar masses each, lies here. Beta Monocerotis is the triple that William Herschel called "one of the most beautiful sights in the heavens".
On December–February evenings, the whole interior of the Winter Triangle — Betelgeuse, Sirius, Procyon — is Monoceros. Its 4th-magnitude stars are hard to join up from a city, but the region itself is easy to place. Turn on "More objects" in the Sky view to see where the Rosette Nebula sits.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.