Magnitude Determines brightness, luminosity, apparent and
absolute magnitude.

Advanced Magnitude Calculator Distance, Luminosity, Apparent and
Absolute Magnitude  if you know two, this calculates the other two.

Perpetual Calendar (1901  2099) Very userfriendly. Just click on the year you want displayed.

Julian Date Calculator Input a month number and year. This will calculate
all the Julian Day Numbers for that entire month.

Planetary Data A chart of planetary data showing mass, diameter, distance from Sun, planetary mass and dentity, etc.

Kepler's 3rd Law Calculator for rudimentary T²=R³ computations.

Kepler's 3rd Law Advanced Calculator This allows mass to be
brought into the T²=R³ equation.

Escape Velocity Ultra Calculator Calculates escape velocity and surface gravity.

Schwarzchild Radius Calculator Calculates the Schwarzchild radius of a black hole.

Synodic Period Calculator Calculates synodic period.

Angular Size Calculator
Accurate for angles up to 180 degrees.

Solar System Calculator
For use in calculating a solar system model to scale.

Mass Luminosity Relationship Tutorial explaining how a star's mass affects its luminosity as well as its radius, temperature, longevity, spectral type and color.

Solar Eclipses Explains solar eclipses.
May 28th 585 BC The Battle of Halys (a river in what is now called Turkey) happened on that date. Do you know what else occurred on that date? A total eclipse of the Sun! Because eclipses can be calculated with extreme precicision, this makes May 28, 585 BC the oldest, most accurately known date in human history!

Positional Astronomy A tutorial about opposition, conjunction, quadrature and synodic period.

Scale of the Universe A listing of celestial objects (by length or distance), starting with the Earth, with each "step" ten times larger than the previous one. Twenty "steps" take you from the diameter of the Earth (12,800,000 meters) to the most distant galaxy ever observed (127,000,000,000,000,000,000,000,000 meters).

Solar System Moons (Satellites)
A listing of over 150 of the natural satellites in the solar sytem. This includes orbital distance, time, mass, size and equations.

The 88 Constellations
A listing of all 88 constellation names, descriptions and discoverers.

Astronomy Statistics
A chart of Solar, Mass, Diameter, Volume, Light Year Distance, Astronomical Unit Distance, Value of pi, etc.

Naked Eye Stars Dimmer Than The Sun
42 Stars that have an Absolute Magnitude higher than 4.85

"Supermoon" explanation
why the Full Moon's apparent size can vary.
