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The learning journal records concepts as they are encountered. This page collects notable facts, backyard observations, unanswered questions and short summaries of material read during research.
A teaspoon of neutron star material would weigh about a billion tonnes on Earth - roughly a mountain.
How much hydrogen the Sun fuses every single second.
A magnetar's magnetic field. Earth's is about 0.5 gauss.
For a few weeks a supernova can be brighter than its entire home galaxy of billions of stars.
The age of the light from the Andromeda galaxy by the time it reaches our eyes.
The iron in your blood and calcium in your bones were forged inside dead stars.
Orion Nebula: Found it below Orion's belt with binoculars. It looks like a faint fuzzy smudge, but it's a stellar nursery with new stars forming inside. Best seen on a moonless night away from streetlights.
The Moon's terminator: The line between light and dark on the Moon is where shadows are longest, so craters appear most dramatic there—not at full Moon as might be expected.
Light pollution: Far more stars were visible in the countryside than in an urban area, illustrating how much city light obscures the night sky.
Unanswered questions are among the most valuable parts of scientific inquiry.
A massive star's iron core can't make energy by fusion, so it collapses in under a second. The outer material falls in, hits the ultra-dense core, and bounces back as a shockwave. Tiny particles called neutrinos help blast the star apart. What's left is a neutron star or black hole, surrounded by an expanding cloud of new elements.
Both are neutron stars. A pulsar shines using the energy of its spin. A magnetar shines using the energy stored in its magnetic field as that field slowly decays. The magnetar's field is roughly a thousand times stronger, which is why it can crack its own crust and fire off gamma rays.