The solar system · wTyqO-tfs7Q · 4:56
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Unit 09 · Earth & Space arc · 7th grade
Eight
minutes old.
The sunlight warming your face left the Sun eight minutes ago. You have never seen the Sun as it is — only as it was. That's the first clue to this unit's big idea: light is how the solar system tells its story, and gravity is what holds the story together.
8 planets
6 manipulatives
12 flashcards
1 time machine
the sunset is old news — 8 minutes old
The phenomenon · the time machine
The sky runs on a delay
Light is fast — 300,000 km every second — but space is faster to be enormous. Every image in the sky arrives late. Press a button, send a photon, and feel the lag.
☉
you
—pick a sender. the dot rides at story speed, not real speed — the NUMBER is the point.
Moonlight is 1.3 seconds old. Sunlight, 8 minutes. Jupiter's glow, about 43 minutes. And the nearest star beyond the Sun? 4.2 years. Telescopes don't just see farther — they see earlier. The sky is a time machine, and looking up is looking back.
Watch · Khan Academy
The neighborhood tour, plus how light behaves
Manipulative 02 · the marble walk
If Earth were a marble…
Shrink Earth to a 1.3 cm marble and keep every proportion honest (that's MS-ESS1-3: scale models of the solar system). The sizes fit in your hand. The distances do not fit in the school.
marble · 1.3 cm
Earth
Everything you've ever known, marble-sized. Hold it carefully.
you are here
exercise ball · 1.4 m
The Sun
99.86% of all the mass in the neighborhood. The anchor.
150 m from the marble — a 2-minute walk
grapefruit · 14 cm
Jupiter
The king. Bigger than all the other planets combined, twice over.
780 m — 10 minutes out
golf ball · 4 cm
Neptune
The last planet. Cold, blue, and very, very far.
4.4 km — an hour's walk
another exercise ball
Proxima Centauri
The nearest star after the Sun — at marble scale it wouldn't fit in your town, your state, or your hemisphere.
40,000 km — the whole way around the REAL EarthThe family line-up
mercury
venus
earth
mars
jupiter
saturn
uranus
neptune
sizes to scale-ish with each other. distances politely lied about — see the marble walk for why. (the asteroid belt guards the gap between mars and jupiter.)
Manipulative 03 · the anchor
Orbits: falling forever, never landing
A planet is always doing two things at once: coasting forward in a straight line (inertia — Unit 05 called this) and falling toward the Sun (gravity — Unit 06). The two combine into an orbit. Cut the gravity and watch which part was the Sun's job.
green arrow = the planet's own motion. it wants a straight line. gravity keeps bending it home.
Standards: MS-ESS1-2 — gravity's role in the motions within the solar system · MS-ESS1-3 — scale properties of solar-system objects · MS-PS4-2 — waves are reflected, absorbed, or transmitted by materials (NGSS Lead States, 2013). DCIs: ESS1.B Earth and the Solar System, PS4.B Electromagnetic Radiation. CCCs: Systems and System Models, Scale, Proportion, and Quantity, Structure and Function.
Manipulative 04 · reflect, absorb, transmit
Light only has three moves
When light meets a material, exactly three things can happen: it reflects, it gets absorbed, or it passes through. Planets shine by rule one. Solar panels eat by rule two. Your glasses work by rule three. Sort the materials.
Pick a material, then file it by its main move.
Reflects
bounces back
Absorbs
takes it in
Transmits
lets it through
0 / 6 filed
Planets are mirrors, not lamps
Nothing out there glows on its own except stars. Every planet, moon, and comet you see is sunlight, reflected. The Moon is the night sky's biggest mirror ball.
Telescopes are light buckets
A bigger mirror catches more photons — which means fainter things, farther things, and older things. Every telescope is also a time telescope.
Visible is one sliver
Light's full family — the electromagnetic spectrum — runs from radio waves to gamma rays. Your eyes get one tiny slice. The universe talks in all of them.
Myth-busters · tap to flip
Unlearn these three things
Manipulative 05 · Spaced repetition
Say it like a scientist
Twelve words. Flip the card, grade yourself honestly, and the deck schedules your next review — hard words come back sooner. Come back tomorrow and it remembers you. (It lives in your browser, no account.)
–due now
–locked in
–seen so far
flip the card, then grade yourself
Practice · Math skills
Marble math
The solar system, shrunk to a scale you can walk: Earth as a marble, light as a speed limit, and Jupiter as 1,331 Earths. Print the sheet, show your work, check the key.
Sketch · sketchnotes
Scale the story before you draw it
The exact page videos are identified. Printable sheets stay pending until transcript and analysis packages pass the sketchnote source gate.
Absorption and reflection · 6uHk1Q-Qb8k · 3:35
Sketchnote in the works
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Investigate · evidence first
Build the scale, then test the claim
The page's scale, light, and gravity models remain usable now; a print-first prediction record is queued after source review.
Investigation in the works
Use the existing page models now. The exact transcript package and classroom record are still pending.
in the worksExit ticket · 5 questions
Before you leave the observatory
No grade, no stakes — just proof the scale stuck. Answer all five to earn the stamp.
question 1 of 5