Physics 01
Why Is a Rainbow 42 Degrees? Descartes' Math Explained
A rainbow sits 42° from the point opposite the Sun because rays leaving a raindrop pile up at a turning point. Derivation, worked numbers and computed plots.
light
Space 02
What Color Is the Sun Really? White, and Here's Why
The Sun is white: a 5772 K spectrum excites all three cone types almost equally. Why it peaks near green but never looks green, and why it turns orange.
Physics 03
Why Is the Sky Blue and Not Violet? The Full Answer
Skylight carries more violet than blue, yet the sky looks blue. We compute the scattered spectrum and run it through human cone data to show why.
Space 04
Why Is the Sky Dark at Night? Olbers' Paradox Solved
In an infinite, eternal universe every sightline ends on a star and the sky would blaze like the Sun. The math of Olbers' paradox and the real answer.
Space 05
Why No Stars in Moon Landing Photos? The Exposure Math
Why are there no stars in Moon landing photos? We run the exposure numbers for the Apollo Hasselblads and show which photos do catch Venus and stars.
Space 06
Why Are Auroras Different Colors? Green, Red and Purple
Green and red auroras come from the same oxygen atom. A 0.75 s vs 134 s lifetime and air density decide which colour wins. The physics, with worked numbers.
Space 07
Why Is the Moon Red During a Lunar Eclipse? The Real Physics
Earth's air bends sunlight 1.1° into its shadow and strips the blue on the way. A worked model of the red Moon, the blue rim and why volcanoes darken it.
Space 08
How a dip in starlight reveals an exoplanet’s size
Infer a planet-to-star radius ratio from a transit light curve, compare Earth and Jupiter signals, and explore why grazing transits need more care.
Physics 09
Reading motion in starlight: redshift, blueshift and spectral fingerprints
Measure a hydrogen line’s Doppler shift, distinguish fractional and absolute wavelength changes, and solve a synthetic mystery spectrum.