Compute orbital period, escape velocity and gravitational acceleration using Kepler’s and Newton’s laws.
An astronomy calculator handles orbital mechanics (Kepler's third law), gravitational acceleration, escape velocity, and stellar magnitude/luminosity calculations. Essential for astrophysics coursework, satellite trajectory planning, and amateur astronomy.
Kepler's third law (T² ∝ a³) governs every orbit in the solar system and beyond. The constant of proportionality involves the mass of the central body — measuring a planet's orbital period and distance gives its star's mass.
T^2 = \frac{4\pi^2}{GM} a^3 \;;\; v_{esc} = \sqrt{\frac{2GM}{r}}
Inputs: Escape velocity from Earth's surface
They formed from a single rotating disk of gas and dust (the solar nebula). Conservation of angular momentum kept everything in roughly the same plane during accretion. Small inclinations (Mercury 7°, Pluto 17°) come from later gravitational interactions and small initial irregularities. The exoplanets observed by Kepler and TESS also typically orbit in coplanar configurations, confirming the model.
Apparent magnitude m measures how bright a star appears from Earth. The scale is logarithmic and inverted: lower magnitude = brighter. A difference of 5 magnitudes corresponds to exactly 100× brightness ratio (each magnitude = 100^(1/5) ≈ 2.512 ratio). Sun: m = −26.7; full Moon: −12.6; Venus at brightest: −4.4; faintest naked-eye stars: +6; faintest telescope objects: +30.
EMI Calculator Mortgage Calculator SIP Calculator Compound Interest GST / VAT Calculator Salary Calculator Unit Converter Currency Converter Scientific Calculator Concrete Calculator Paint Calculator Tile Calculator Calorie / TDEE Body Fat Macro Calculator O-Ring Sizes Bolt & Nut Sizes Pipe Sizes Wire Gauge AWG Needle Gauge Chart IV Cannula Sizes Suture Sizes Catheter French Sizes Drug Dosage See all 90+ calculators ›