Hercules
What is Hercules?
Constellations· Summer evenings (N) · the Keystone between Vega and Arcturus. The kneeling hero Heracles — fifth-largest constellation but without bright stars, found by the trapezoid "Keystone" of its body. On one side of the Keystone sits M13, the finest globular cluster in the northern sky, visible as a haze in binoculars.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Hercules is in your sky right now: https://nowsky.org/solar/sky?sel=con:Hercules — location and time set automatically, no login.
Stars of the figure
| Star | Magnitude |
|---|---|
| Rasalgethi | 3.1 |
The 1 brightest of the 18 stars used in the figure (19 lines). Lower magnitude means brighter.
Deep-sky objects near this constellation
Constellation basics
| Season | summer evenings, June–August |
|---|---|
| Brightest star | Kornephoros (2.8) |
| How to find | the four-star trapezoid, the Keystone, midway between Vega and Arcturus |
| Area rank | 5th of 88 |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Frequently asked
- When can I see Hercules?
- summer evenings, June–August.
- How do I find Hercules?
- the four-star trapezoid, the Keystone, midway between Vega and Arcturus.
- What is the brightest star in Hercules?
- Rasalgethi, magnitude 3.1.
- Where is Hercules in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
Where the solar system is heading — the solar apex in Hercules
The whole solar system moves at about 20 km/s relative to the neighbouring stars, and the direction is Hercules. The point, not far from Vega, is called the solar apex, and William Herschel found it in 1783 by noticing that the proper motions of stars seemed to spread out from one direction and converge toward the opposite one, a perspective effect of stars opening ahead and closing behind.
Twenty kilometres a second is 600 million kilometres a year, about 4 AU. While Earth circles the Sun, the Sun itself advances that far toward Hercules, so Earth's true path is not a circle but a helix. This motion is separate from the galaxy's rotation at 220 km/s; it is our drift relative to the nearby stars. The Keystone overhead on summer nights is a constellation and, at the same time, a signpost to where we are going.
The constellation in depth
Hercules shows the hero of the twelve labours on one knee. The Greeks first knew the figure simply as "the Kneeler", without a name, and later identified him as Heracles trampling the dragon Ladon — his foot does rest on the head of Draco. The figure appears upside down from the northern hemisphere, with his head to the south and his feet toward the pole.
M13, on the western side of the Keystone, is a globular cluster 25,000 light-years away packing hundreds of thousands of stars; in 1974 the Arecibo radio telescope beamed a message toward it. Rasalgethi is a red giant 400 Suns wide that splits in a telescope into an orange-and-green pair. The Solar System is travelling toward this constellation at about 20 km per second.
On summer evenings look midway between Vega overhead and Arcturus in the west for four stars in a trapezoid — the Keystone — from which the limbs spread outward. About a third of the way along the Keystone's western side, binoculars show M13 as a small cotton ball. Set the Sky view to a July night with deep-sky objects on to see the cluster marked.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.