Space 01
How Do We Know How Far Away Stars Are? Parallax Math
Proxima Centauri shifts 0.768 arcsec a year, which puts it 4.2465 light-years away. Here is the parallax math, what Gaia changed and the distance ladder.
astronomy
Space 02
How Much Does a Teaspoon of Neutron Star Weigh?
A 5 mL teaspoon of average neutron star weighs about 1.9 billion tonnes, not the 10 million often quoted. The density math, and what it would do on Earth.
Space 03
How We Know 3I/ATLAS Is Interstellar: Orbit Math
3I/ATLAS has eccentricity 6.1 and leaves at 58 km/s. We compute its orbital energy, compare 'Oumuamua and Borisov, and show why no planet could fling it.
Space 04
Why Is James Webb at L2? The Physics, Computed
Webb orbits L2, 1.5 million km out, so Sun, Earth and Moon stay on one side. L2 isn't where gravity cancels, and sitting at it means an endless eclipse.
Space 05
Why We Only See One Side of the Moon (and It's 59%)
The Moon is tidally locked, spinning once per 27.3-day orbit. The torque that locked it, why we see 59% of it, and why it drifts 3.8 cm a year.
Space 06
Why Stars Twinkle but Planets Don't (With the Math)
Stars twinkle because they are points that cross one 7 cm air patch at a time. Planets span hundreds of patches. Here is the arcsecond math, with figures.
Space 07
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 08
Why Does Venus Spin Backwards? The Tidal Explanation
Venus turns once every 243 days, backwards, giving a 116.75-day solar day. Why atmospheric tides, not a giant impact, are the leading explanation.
Space 09
Moon Illusion Explained: Why the Horizon Moon Looks Big
The horizon Moon looks huge, yet it's 1.7% narrower and 16% shorter than overhead. We measure it, then weigh the theories for why your brain inflates it.
Space 10
How Fast Is Earth Moving Through Space? Every Frame
Earth spins at up to 465 m/s, orbits at 29.8 km/s and moves at 370 km/s relative to the CMB. How each speed is measured, and why they don't add.
Space 11
Why the 2027 Solar Eclipse Lasts 6 Minutes 23 Seconds
The 2 August 2027 eclipse gives 6 min 23 s of totality near Luxor. We compute why: a near-perigee Moon, a far Sun, and a shadow slowed by Earth's spin.
Space 12
How Cold Is Space? 2.7 K, 120 °C and Everything Between
Deep space glows at 2.7 K, yet a sunlit plate near Earth hits 120 °C and ISS-height gas tops 700 K. What "the temperature of space" really means.
Space 13
What Happens If You Fall Into a Black Hole? The Real Numbers
At a stellar black hole's horizon the stretch is 21 million g. At Sgr A* it is 0.0001 g. Tidal math, your clock and what outsiders see, worked out.
Space 14
How Bright Will Betelgeuse's Supernova Be? The Math
Betelgeuse's supernova should peak near magnitude -10 to -11: about 250 times Venus and a seventh of the full Moon. The magnitude math, step by step.
Reviews 15
Which astronomy course should you choose? Start with the work you want to do
Compare Arizona’s astronomy survey, Edinburgh’s AstroTech and free MIT problem sets by learning goal, access costs and what each route leaves out.
Space 16
How much does sunlight change around a planetary orbit? A Python comparison
The same inverse-square calculation gives Earth about a 7% close-to-far sunlight increase and Mercury about 130%. Reproduce all eight comparisons.
Physics 17
10 Cosmic Objects That Will amaze you
The universe is a vast and beautiful place, filled with cosmic objects that leave us in awe. In this blog, we'll explore ten of the most stunning and
Space 18
Why Wood is more Valuable than Diamonds in the whole Universe
Recently a fact on the viral that woods are more valuable than diamonds but why is it? I mean, if you go to a jewellery shop and a wood shop will find that diamonds are more valuable than woods. Even the raw diamonds are more beautiful than so why the question?...