About 61 Cyg
Description
61 Cygni is a wide binary of two orange K-dwarfs about 11.4 light-years away — the 14th closest stellar system to the Sun. The components, K5 V and K7 V, shine at magnitudes 5.21 and 6.05 and orbit each other every 678 years at a current separation of roughly 31 arcseconds. Both stars are flare-active, and the brighter component hosts a confirmed planetary candidate from radial-velocity work.
Observing Tips
An easy split in any telescope or even big binoculars — the 31″ gap is wide and the magnitude difference is only one stop. The two stars show a delicate orange tint side-by-side, a textbook K-dwarf pair. Use a low-power eyepiece to enjoy the colour. Best in the autumn evenings high in Cygnus, just east of Tau Cygni.
History
Friedrich Wilhelm Bessel chose 61 Cygni in 1838 for the first successful stellar parallax measurement, deriving a distance of 10.4 light-years (close to today's 11.4). The choice was deliberate: the system has the seventh-largest proper motion of any naked-eye star — 5.2″ per year — and Bessel reasoned that a fast-moving star must be nearby. His result finally proved that the Earth orbits the Sun, two centuries after Galileo.
Fun Facts
Giuseppe Piazzi nicknamed it the "Flying Star" in 1804 because of its rapid proper motion — at the eyepiece you cannot see it move in real time, but two photographs taken a decade apart show a clearly displaced position against the background stars.
Observe
1Physical Properties
2Position & Identifiers
3How easy to split?
| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | Easy | Easy | Easy |
| 150 mm Newton 150mm Newt. | Easy | Easy | Easy |
| Celestron C8 (203 mm SCT) C8 203mm | Easy | Easy | Easy |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
4Visibility
Set a location in User Settings to see visibility data.
5Multiple Star System Sextuple
Separation over time
Apparent separation over time, computed from ORB6 orbital elements. Steep curves indicate fast-changing pairs — catch them while they're splittable.
Eyepiece View
A: 5.2 · B: 6.1 · Sep: 32.1″ · PA: 154° · N up, E right
Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″
Explore
6
Size Comparison
7
Compare Stars
8
Spectral Classification
9
Hertzsprung-Russell Diagram
10
Stellar Lifecycle
11
Blackbody Spectrum
12
Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
13
Stellar Fusion
Discover
14Stellar Notes
15
Light Travel Time Machine
16
Relativistic Travel
Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
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