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Scale of the Universe

Scale of the Universe is a free interactive simulation of cosmic scale for GCSE Physics (Edexcel IGCSE 4PH1). Students scroll through ten stages, from a person to the observable universe, to build a sense of how vast the jumps between astronomical distances and sizes are. No login required — includes a self-marking quiz.

Aim: To explore the scale of objects in the universe, from a human to the observable universe.

Scroll down to begin the journey ↓

Scale Comparisons

Comparison Factor Context
Human → Earth × 7 million Earth's diameter is about 7 million times a person's height
Earth → Sun × 109 You could line up 109 Earths across the Sun's diameter
Sun → Solar System × 6,400 The Solar System (to Neptune) is ~6,400 times the Sun's diameter
Solar System → Milky Way × 6.3 billion Our galaxy contains 100–400 billion stars spread across 100,000 light-years
Milky Way → Observable Universe × 930,000 The observable universe is 93 billion light-years across and contains ~2 trillion galaxies
  1. Scroll down slowly from the start. Pause on each of the ten stages and read the stage name, its size, and the note shown in the panel.
  2. Write down the size given at every stage, converting them all to the same unit (metres) so they are easy to compare.
  3. Keep scrolling until you reach the Scale Comparisons table at the end, and record the "factor" listed for each jump from one stage to the next.
  4. Which single jump in the table has the largest factor? Which has the smallest?
  5. Roughly how many powers of ten (multiples of ×10) does the size increase by overall, from a human all the way out to the observable universe?
  6. Click Quiz yourself! at the top of the page and complete the self-marking quiz to check what you remember about the ten stages.
  7. Pick the two consecutive stages whose jump in scale surprised you the most, and explain in your own words why that jump is so much bigger than the others.