The Solar System- Earth

Our Home in the Cosmos

Earth, the third planet from the Sun, is the only known celestial body that harbours life. Often called the Blue Planet because of its vast oceans, Earth stands unique in the Solar System — a vibrant world where land, water, and atmosphere coexist in perfect harmony. It formed over 4 billion years ago, evolving into a dynamic planet teeming with biodiversity and natural wonders.

Physical and Atmospheric Characteristics

Earth’s equatorial diameter is approximately 12,756 km, and it has a mass of 386.26 × 10²⁴ kg. Its total surface area is 510.1 million km², of which about 71% (362.124 million km²) is covered by water, mainly in oceans, seas, and lakes. The remaining 29% is land — comprising continents, islands, mountains, deserts, and forests.

The planet’s composition includes oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), and calcium (1.5%). Earth’s average density is 5.514 g/cm³, and its surface gravity is 9.807 m/s², making it the densest planet in the Solar System.

Earth’s atmosphere is crucial for sustaining life. Composed of about 78% nitrogen and 21% oxygen, along with trace amounts of water vapour, carbon dioxide, and noble gases, it protects the planet from harmful solar radiation and moderates surface temperatures. This delicate atmospheric balance has allowed ecosystems to thrive for millions of years.

The Only Planet with Life

Unlike any other planet, Earth possesses the perfect combination of factors necessary for life — liquid water, a suitable atmosphere, and moderate temperatures. Its distance from the Sun places it in the “habitable zone”, where conditions are just right to support a wide variety of organisms. The presence of water in all three states — solid, liquid, and gas — plays a key role in maintaining life cycles and weather patterns.

Earth’s natural satellite, the Moon, influences tides and stabilizes the planet’s axial tilt, ensuring a relatively stable climate. Together with the Sun and other celestial bodies, Earth forms an integral part of the vast Solar System.

A Planet of Change and Wonder

From towering mountains to deep ocean trenches, from tropical rainforests to icy polar regions, Earth’s landscapes are a testament to its geological and biological diversity. Over billions of years, it has witnessed the birth and extinction of species, the drifting of continents, and the rise of human civilization. Earth continues to evolve — reminding us of the need to preserve its delicate ecological balance for future generations.

Philatelic Tribute to Earth

In recognition of its singular status as the cradle of life, the Department of Posts issued a commemorative postage stamp on Earth as part of the Solar System series. The stamp artistically portrays our planet’s blue oceans, green continents, and swirling clouds, symbolizing vitality, unity, and balance.

This philatelic issue celebrates Earth as the living heart of the Solar System — a planet of beauty, resilience, and eternal wonder.