Science quiz
Planets in order of density
Eight planets, densest to least dense. The rocky planets lead; the order among the giants is the hard part.
- Format
- Put them in order
- Items
- 8 to sort
- Limit
- None
- Level
- Hard
- Checked
- 2026.10.03
See every entry and put the whole list in order.
- Entries
- 8
- Sort by
- Bulk density
- Time limit
- None
- Touch screens start in Tap mode: tap the entries in order, and tap one again to take it back.
- Drag mode: drag an entry (press and hold on a phone), or use the arrow buttons.
- Keyboard: space to pick up, arrows to move, space to drop.
- Pause whenever you like (Esc). The board hides while the clock is stopped.
About this quiz
Bulk density is a planet's mass divided by its volume. The four rocky planets are several times denser than the four giants, which are mostly hydrogen, helium and ices.
- Earth is the densest planet, narrowly ahead of Mercury.
- Saturn is less dense than water, which is 1 gram per cubic centimetre.
- Neptune is the densest of the four giants.
Sources
- [1]NASA Jet Propulsion Laboratory. Planetary Physical Parameters.
Note on the data. Densities are the table's bulk densities, shown to two decimal places. Radii, masses, densities, rotation and orbital periods, gravity and escape velocities are the figures in the JPL Solar System Dynamics tables of planetary physical parameters, read on 3 October 2026. The five dwarf planets are the five in that table, which are the five the International Astronomical Union recognises.
Last checked October 3, 2026
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