11]Earth- Sweet Home
Earth is the third planet from the Sun. We have learnt about Earth since childhood. Here I will cover some facts and provide quick glances at the basic information which everyone must know about our home planet.
Some facts about Earth:
Diameter- 12,742 km
Orbital period- 365.25 days
Day- 23 hours, 56 minutes, and 4 seconds
Axis tilt- 23.5 degrees
Distance from sun- 1AU
Earth is the only object known to harbor and support life in the universe so far. About 29.2% of Earth’s surface is land consisting of continents and islands. The remaining 70.8% is covered with water, mostly by oceans, seas, lakes, rivers, and other water bodies, which together constitute the hydrosphere. Much of Earth’s polar regions are covered in ice and many glaciers are present.
Lithosphere and Structure of Earth
Earth is the densest planet in the Solar System and the largest and most massive of the four rocky planets. Earth’s outer layer is divided into several rigid tectonic plates that migrate across the surface over many millions of years, while its interior remains active with a solid iron inner core, a liquid outer core that generates Earth’s magnetic field, and a convective mantle that drives plate tectonics. The Earth’s crust ranges from 5–70 kilometres (3.1–43.5 mi) in depth and is the outermost layer. Earth’s mantle extends to a depth of 2,890 km, making it the planet’s thickest layer.
Earth’s atmosphere consists of various gases which are (by volume) -78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases. The atmosphere has various layers. From highest to lowest, the five main layers are:
- Exosphere: 700 to 10,000 km (440 to 6,200 miles)
- Thermosphere: 80 to 700 km (50 to 440 miles)
- Mesosphere: 50 to 80 km (31 to 50 miles)
- Stratosphere: 12 to 50 km (7 to 31 miles)
- Troposphere: 0 to 12 km (0 to 7 miles)
Gravity and Orbit
The gravitational acceleration on Earth’s surface is considered to be 9.8 ms-2 . Earth’s gravity interacts with other objects in space, especially the Moon, which is Earth’s only natural satellite. Earth orbits around the Sun in about 365.25 days. Earth’s axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth. The gravitational interaction between Earth and the Moon causes tides, stabilizes Earth’s orientation on its axis, and gradually slows its rotation.
History of Earth and Life
According to radiometric dating estimation and other evidence, Earth formed over 4.5 billion years ago. Within the first billion years of Earth’s history, life appeared in the oceans and began to affect Earth’s atmosphere and surface, leading to the proliferation of anaerobic and, later, aerobic organisms. Some geological evidence indicates that life may have arisen as early as 4.1 billion years ago. Since then, the combination of Earth’s distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive. In the history of life on Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinctions. Over 99% of all species that ever lived on Earth are extinct. Almost 8 billion humans live on Earth and depend on its biosphere and natural resources for their survival. Humans increasingly impact Earth’s surface, hydrology, atmospheric processes, and other life.
Recently, Earth has been facing many problems due to human activities. It is the responsibility of humans to fix these problems- Global warming and climate change. Carbon emissions and overpopulation is leading to the creation of many environmental as well as social problems. We must stand up for our Earth and contribute as much as we can, since every step matters.