Size comparison: Earth vs Tethys

Size comparison between the Earth and the moon Tethys.

Tethys is a mid-sized moon of Saturn. This satellite was discovered in 1684 by the Italian methematician and astronomer Cassini. Tethys has the lowest gravity of Saturn's moons, this is due to its composition which is mostly ice water. Spectroscopy of its surface confirmed this hypothesis. The nature of some dark materials on the surface could not be identified. We notice that the surface of Thétys presents many craters; the largest crater is 400 km in diameter. Tethys formed from one of the gas and dust disks that surround the planet Saturn.

The Pioneer 11, Voyager 1, Voyager 2 and Cassini probes approached this satellite between 1979 and 2017.

Object	Earth	Tethys
Type	Rocky planet	Rocky satellite
Age	4.54 billion years	4.53 billion years
Population	7.7 billion	0
Diameter	12,742 km	1,062 km
Mean radius	6,371 km	531 km
Mass	5.97 × 1024 kg	6.17 × 1020 kg
Orbital period	365 days	1.88 days
Surface temperature (average)	288 K 14.9 °C 58.7 °F	86 K -187.1 °C -304 °F
Surface gravity	9.8 m/s²	0.14 m/s²
Mean density	5.5 g/cm3	0.98 g/cm3
Orbital distance	150 million km	294,660 km
Circumference	40,075 km	3,336 km
Surface area	510 million km²	3.5 million km²
Volume	1.08 × 1012 km3	0.62 × 109 km3
Escape velocity	11.1 km/s	0.39 km/s
Average orbital speed	29.78 km/s	11.35 km/s
Semi major axis	149 million km	294,619 km
Inclination	7.1°	1.12°
Crust composition	60% silica, 16% alumina, 6% lime, 6% iron oxide, 4% magnesia, 3% sodium oxide, 2% potassium oxide	water ice, silicate
Distance from the Milky Way center	27,200 light years	27,200 light years

Note: if one of the objects is not visible, it just means that it is too tiny to be displayed compared to the other one.