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The **Astronomy Calculator** includes functions that are useful for studying astronomy. Formulae are organized in different tabs to the right as follows:

- Kepler's 3
^{rd}Law formula T² = (4π • R³)/(G • M) - Small Angle Formula
*Small Angle Formula**α = S / D* - Flux and Magnitude formulas
- Telescope formulas
- Mass formulas
- Relative Size Formulas
- Wavelength Formulas
- Luminosity and other Formulas

**Distance Units:** The functions have length units that are often defaulted to au (astronomical units) which is the mean distance from the Sun to the Earth. However, users can automatically change the distance units on both the inputs to the calculator and the solved answers via the pull-down menu. The distance units are automatically handled and range from extremely small (nano-meters) to truly astronomical including au, light seconds, light minutes, light years, parsecs, kilo-light years and mega-parses.

**Mass Units:** The calculator functions have mass units that often default to multiples of the mass of the sun (solar_mass). However, users can automatically change the mass units on both the inputs to the calculator and the solved answers via the pull-down menu. The mass units are automatically handled and range from extremely small (grains) to truly astronomical including Earth masses, Jupiter masses and Solar masses.

**Time Units:** The calculator functions have time duration units that default to days. However, users can automatically change the time units on both the inputs to the calculator and the solved answers via the pull-down menu. The time units are automatically handled and range from extremely small (nanoseconds) to large including weeks, months, years, decades and centuries. They also include sidereal day and sidereal years.

**Related Astro Calculators:**

- Hubble's Law
- Kepler's 3
^{rd}Law Calc has Kepler's 3^{rd}law solved for each parameter. - Astronomy Calculator contains basic formulas for a college level Introduction to Astronomy
- Exoplanet Calculator contains formulas for studying planets outside of our Solar System.
- Orbital Radial Acceleration
- Distance to Barycenter
- Sakuma-Hattori Equation
- Astronomical Distance Calculator provides the distance from the Earth to numerous astronomical bodies (e.g. Sun, Moon, planets, stars, Milky Way's Center and Edge, Andromeda Galaxy)
- Astronomical Distance Travel Time Calculator computes the time to travel to distant parts of space at different velocities.
- Ellipse Calculator
- 3D Vector Calculator:
- Drake Equation Calculator
- Seager Equation Calculator
- Friedman Equation Calculator
- Black Hole Mass Calculator
- Black Hole Event Horizon Calculator

Special thanks to Dr. Stephen Spicklemire, Department Chair, Physics &Earth-Space Science, Associate Professor of Physics at the University of Indianapolis. Dr. Spicklemire created this calculator and all of the underlying equations (functions) to help his astronomy students.

"vCalc is **awesome** for my astronomy students. With vCalc I can give them real problems that would normally require fairly sophisticated reasoning **and** mathematics, and now they can **do** the reasoning, because they’re not daunted by the math. It’s great." Dr. Steve Spicklemire