Unit 05 · The Sun & the Stars
Our Sun is the one star we can study up close, and it opens the door to all the others. This unit works from the Sun's layered structure and the hydrogen fusion that powers it out to the properties that define any star — luminosity, temperature, color, and mass — and organizes them on the H–R diagram, where a star's position reveals its stage. You'll trace how stars live and die by their mass, from the main sequence to giants and on to white dwarfs, neutron stars, or black holes, and learn how astronomers measure the distances with parallax and Cepheid variables — Henrietta Leavitt's period–luminosity law. Mastery includes one strict safety rule: you observe sunspots only by projection, never looking at the Sun directly.
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| The Sun's structure & fusion | Thinks the Sun burns like an ordinary fire. | Says fusion but cannot locate it or name the Sun's layers. | Describes the Sun's layers and explains its energy as hydrogen fusion in the core. |
| Stellar properties | Assumes all stars are essentially alike. | Names a property or two but cannot read color as temperature. | Relates luminosity, temperature, color, and mass, reading a star's color as a clue to its temperature. |
| The H–R diagram | Cannot read the diagram. | Locates the main sequence but not the giants or dwarfs. | Places stars on an H–R diagram and reads each one's stage from its position. |
| Stellar life cycles by mass | Thinks every star ends the same way. | Names one endpoint but not the mass that decides it. | Traces life cycles by mass — main sequence to giant to white dwarf, neutron star, or black hole. |
| Distance & safe solar observation | Has no distance method and would look at the Sun directly. | Names parallax but not Cepheids, and observes sunspots carelessly. | Measures distance by parallax and Cepheid variables (Leavitt's period–luminosity law) and observes sunspots safely by projection — never directly — logging them across weeks. |
| Integration (cross-domain) | Treats the science as isolated facts; makes no cross-domain connection. | Names a link to history, reading, or writing but cannot defend why it matters. | Connects the unit to its anchor across History · Reading · Writing (plus chosen electives) and defends why the connection matters. |
“The Sun shines by fusing hydrogen in its core, not by burning. A star’s color tells me its temperature, and where it sits on the H–R diagram tells me its stage. Massive stars die as neutron stars or black holes; the Sun will end as a white dwarf. I found a star’s distance from a Cepheid’s period — and I only ever watch sunspots by projection, never straight at the Sun.”
“Stars are just balls of fire, and bigger ones are hotter, maybe? The Sun will explode someday. I’m not sure how you’d measure how far away a star is.”
You demonstrate this unit by placing stars on an H–R diagram, reasoning through stellar life cycles, and observing sunspots safely by projection in your dated journal — never looking at the Sun directly, and never on a multiple-choice test. A criterion counts as mastered only when you can both read a star's stage from evidence and observe the Sun safely. Mastery is demonstrated, not awarded.
A 5-page clipboard packet — unit overview, key terms, the mastery rubric, anchor examples, and a score sheet you can print and grade against.