🌌 Astronomy Calculator - Full Version

Responsive single-file astronomy utility for iPhone, iPad, and desktop browsers. Includes light-travel time, angular size, parallax, Kepler orbital period, telescope magnification, escape velocity, stellar magnitude, redshift, unit conversion, and a downloadable CSV orbital simulator with graph output.
Mobile friendly Offline capable Single HTML file CSV export Graph included

1) Light-Travel Time

Enter a distance to calculate how long light takes to travel.

2) Angular Size

Computes apparent angular diameter in degrees, arcminutes, and arcseconds.

3) Parallax Distance

Distance = 1 / parallax(arcsec).

4) Kepler Orbital Period

Uses Newton/Kepler form: T = 2π√(a³/GM).

5) Telescope Magnification & True Field

Magnification = telescope focal length × barlow ÷ eyepiece focal length.

6) Escape Velocity

v = √(2GM/R)

7) Magnitude / Distance Modulus

m − M = 5 log10(d) − 5

8) Redshift Velocity (low-z approximation)

For small z, recession velocity ≈ zc, and distance ≈ v/H₀.

9) Unit Converter

Common astronomy length units.

10) Orbital Speed

Circular orbital speed: v = √(GM/r)

11) Surface Gravity

g = GM / R²

12) Luminosity from Radius & Temperature

L = 4πR²σT⁴

13) “What If” Orbit Simulator

Value: 0.02
Generates orbital period, periapsis, apoapsis, circular speed estimate, an orbit table, and a graph.
Step Angle (deg) Radius x y

Quick Constants

c = 299,792.458 km/s
1 AU = 149,597,870.7 km
1 ly = 9.4607304725808 × 1012 km
1 pc = 3.26156 ly
G = 6.67430 × 10−11 m³/kg/s²
σ = 5.670374419 × 10−8 W·m−2·K−4
M☉ = 1.98847 × 1030 kg
R☉ = 695,700 km
L☉ = 3.828 × 1026 W
M⊕ = 5.9722 × 1024 kg
R⊕ = 6,371 km
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