Binary Star Observer

Orbit & Earth line of sight

Star 1Star 2Earth (+Z)Orbital pole

View from Earth

Magnified disks · sky plane X–Y

No eclipse

Relative brightness

Combined light · outside eclipse = 1

Phase0.250

Phase is time / period measured from periastron. Eclipse A: star 1 behind; eclipse B: star 2 behind.

Binary system

Orientation

Inclination i

Face-on 0°Edge-on 90°

Periastron angle ω

Stellar disks

Radius sum (R₁ + R₂) / a

Radius ratio R₂ / R₁

R₁ / a R₂ / a

Surface brightness J₂ / J₁

Quadratic limb darkening

u₁ = 0.40 · u₂ = 0.25 · both stars

Orbit

Eccentricity e

Mass ratio M₂ / M₁

Model & Julia source

Keplerian, spherical detached stars with no third light, spots, reflection, tidal distortion or Doppler beaming. Stellar colors are labels, not temperatures.

Earth sees projected X–Y disks along fixed +Z. Inspection-camera motion does not change that observer. The unresolved view represents combined photometric light, not resolved telescope imaging.

Quadratic intensity: I(μ) / I(1) = 1 − 0.4(1 − μ) − 0.25(1 − μ)². The browser interpolates a precomputed Transits.jl kernel; uniform disks use exact overlap geometry.

Probability boundaries maximize allowed |cos i| over each half-orbit, rather than approximating conjunction as exactly edge-on. The two events share the same inclination.

Timing, eclipse duration and depth do not uniquely determine a binary without additional constraints.

Geometric eclipse probability
Julia source · Reference curves
Offline project · Provenance
License · Dependencies

Orbit & Earth line of sight

View from Earth

Relative brightness

Random orbital orientations

2,400 equally weighted orientations