Crater
What is Crater?
Constellations· Spring evenings (N) · faint goblet on Hydra's back, west of Corvus. Apollo's cup, resting on the back of Hydra just west of Corvus, drawn by stars of around 4th magnitude. It shares one myth with the crow and the water snake, which makes the three easy to remember together.
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Stars of the figure
| Star | Magnitude |
|---|---|
| Labrum | 3.6 |
| Alkes | 4.1 |
| Gamma Crateris | 4.7 |
The 3 brightest of the 3 stars used in the figure (2 lines). Lower magnitude means brighter.
Constellation basics
| Season | spring evenings (N) |
|---|---|
| Brightest star | Delta Crateris (3.6) |
| How to find | west of Corvus, south of Leo |
| Area rank | 88 |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
The feeble giant beyond the cup — Crater II
In 2016 a new small galaxy orbiting the Milky Way was found about 380,000 light-years away in the direction of Crater. Named Crater II, it is more than 6,000 light-years across, large for a satellite galaxy. Yet its stars are so thinly scattered that it is among the faintest galaxies known for its size. The discovery paper called it a feeble giant.
This part of the sky had been watched for centuries, but the galaxy showed up only when computers carefully analysed how countless stars were spread across survey images. Its stars move very slowly. Two explanations compete: it holds less dark matter than expected, or the Milky Way's gravity has already stripped much of it away. Finds like this suggest there may be more hidden small galaxies than we thought.
The constellation in depth
Crater is one of Ptolemy's 48 constellations. It is the cup Apollo gave the crow to fetch water, placed in the sky along with the bird as part of its punishment for coming back late. The Babylonians saw the crow and the cup as a single figure, and some Greek writers called it the wine cup of Dionysus.
The Alpha star, Alkes, means ‘the cup’ in Arabic, yet at magnitude 4.1 it is not the brightest. That honour goes to Delta, at 3.6. When Bayer lettered the stars in 1603, he did not always follow the order of brightness. There are no showpiece objects, but small telescopes can pick up faint galaxies such as NGC 3511 and NGC 3513.
In East Asia these stars were a bird's wing. Yi, the twenty-seventh of the 28 lunar mansions of old Chinese astronomy, was the wing of the Vermilion Bird that guards the southern sky, and most of its stars lie in Crater. Neighbouring Corvus became the twenty-eighth mansion, Zhen, the bird's tail. Stars that Greece split into a cup and a crow were joined in East Asia into a single bird.
On April and May evenings, first find the box of Corvus in the south, then look a little over 10 degrees to its west. Its stars are around 4th magnitude, so the cup almost disappears under city lights. In the Sky view, select Corvus and turn on constellation lines to trace the cup's outline.
Frequently asked
- When can I see Crater?
- Crater is best seen in spring evenings (N).
- How do I find Crater?
- To find Crater, look for west of Corvus, south of Leo.
- What is the brightest star in Crater?
- The brightest star in Crater is Labrum, at magnitude 3.6.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.