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Putting sizes in perspective

Mars and Earth: a size comparison

The same metres-per-pixel factor applies to both planets. Their images allow the diameters to be compared without independently changing their framing.

Earth: a dimension about 1.88 times that of Mars using the adopted values.

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Is Mars smaller than Earth?

Dimensions adopted for the calculation
ReferenceDimension
Mars6,779 km
Mean diameter ≈ 6 779 km
Earth12,742 km
Mean diameter ≈ 12 740 km

Calculation: 12,742 km ÷ 6,779 km, after conversion into the same unit. The ratio calculated from the catalogue data is about 1.88.

Both illustrations use a common factor for the stated dimension. Positions aid reading and do not represent physical separation.

Check the conventions

Mars

Mean diameter calculated from the volume-equivalent radius in the NASA/JPL table. Rings and the outer atmosphere are excluded.

Approximate catalogue reference; a source is provided, but the measurement has not been individually audited.

Earth

Mean diameter calculated from the volume-equivalent radius in the NASA/JPL table. Rings and the outer atmosphere are excluded.

Approximate catalogue reference; a source is provided, but the measurement has not been individually audited.

Choose another reference

Replace an object in the explorer, keep the common scale factor and try predicting the new ratio before reading it.

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