The notable differences between Earth and Venus, and Earth and Mars, can be summarized across several key aspects:
Earth vs. Venus
- Size and Mass : Venus is very similar to Earth in size and mass, with a diameter about 95% that of Earth (12,104 km vs. 12,742 km) and a mass about 81% of Earth's
- Rotation : Earth rotates once every 24 hours, while Venus has a very slow retrograde rotation, taking 243 Earth days to complete one rotation, spinning opposite to most planets including Earth
- Atmosphere : Venus has a thick atmosphere about 90 times denser than Earth's, composed mainly of 96% carbon dioxide and 3% nitrogen, leading to an extreme greenhouse effect and surface temperatures around 465°C, compared to Earth's nitrogen-oxygen atmosphere and average 15°C surface temperature
- Surface Pressure and Temperature : Venus' surface pressure is about 90 bars (90 times Earth's sea level pressure), making its environment extremely hostile compared to Earth's 1 bar pressure
- Axial Tilt : Venus has an axial tilt of about 178°, meaning it essentially rotates upside down, whereas Earth’s axial tilt is about 23.5°, which contributes to seasonal climate variations
- Surface Features : Venus has mountainous regions and volcanic plains, but no liquid water, while Earth has diverse landforms and about 70% of its surface covered by liquid water
Earth vs. Mars
- Size and Mass : Mars is much smaller than Earth, with a diameter about 53% that of Earth (6,794 km vs. 12,742 km) and only about 10% of Earth's mass
- Gravity : Mars’ surface gravity is about 37.6% of Earth’s, due to its smaller size and mass
- Atmosphere : Mars has a very thin atmosphere (~1% of Earth's pressure) composed mostly of carbon dioxide (96%), with only trace amounts of nitrogen and oxygen, resulting in a cold and dry environment. Earth’s atmosphere is dense and rich in nitrogen (78%) and oxygen (21%)
- Water Presence : Earth has abundant liquid water on its surface, covering about 70%, essential for life. Mars currently has no liquid water on the surface, only ice at the poles and possibly subsurface ice, as its thin atmosphere and low gravity allow water to escape easily
- Geological Activity : Earth has active plate tectonics and a magnetic field generated by a liquid iron core, which helps retain its atmosphere and protect life. Mars cooled quickly, lost its magnetic field, and has no plate tectonics, leading to an older, cratered surface and atmospheric loss to space
- Surface Temperature : Mars is much colder, with average surface temperatures around -60°C, compared to Earth's average of 14°C
In summary, Venus is Earth’s closest twin in size and mass but differs drastically in atmosphere, rotation, and surface conditions, making it extremely hot and inhospitable. Mars is smaller and colder with a thin atmosphere and no liquid surface water, contrasting with Earth’s life- supporting environment and active geology
