Earth, Nine Planets in Universe
Earth is the third planet from the Sun and the fifth largest planet in the Solar System with the highest density. It is currently the only known location where life is present.
The Earth is believed to have formed around 4.5 billion years ago. The duration for this formation has been estimated to have lasted about 10 to 20 million years.
The theory states that a solar nebula partitions a volume out of a molecular cloud by gravitational collapse which begins to spin and flatten into a circumstellar disk.
The planets grow out of that disk through gravity pulling swirling dust and gas. Slowly, the Earth’s atmosphere and oceans were formed by volcanic activity and outgassing.
It is believed that water vapor condensed into the oceans being augmented by water and ice from asteroids, protoplanets, and comets.
Through periods of hundreds of millions of years, the supercontinents have assembled and then broke apart. About 750 million years ago, the earliest known supercontinent Rodinia began to break apart.
The continents later rejoined and combined again to form Pannotia about 600 to 540 million years ago. This happened again and the supercontinent of Pangaea formed but also broke apart about 180 million years ago.
There are patterns that suggest that ice ages began about 40 million years ago and intensified during the Pleistocene around 3 million years ago. Many high-latitude regions have undergone repeated cycles of glaciation and thaw, repeating about every 40.000 to 100.000 years. It is believed that the last continental glaciation ended 10.000 years ago.
Distance, Size and Mass
Earth is the third planet from the Sun, at a distance of 1 AU or 147 million km / 91 million mi. It is situated in the goldilocks zone where temperatures are just right for liquid water to exist and for life to evolve.
Depending upon their current orbital positions, either Venus or Mercury are the closest planets to Earth. It has an equatorial radius of 6.371 km / 3.958 mi, and a polar radius of 6.356 km / 3.949 mi, meaning it is not completely spherical but rather bulged at the equator due to rotation.
Orbit and Rotation
The Earth makes a complete rotation on its axis once every 23.9 hours. It takes Earth 265,25 days to complete one trip around the Sun – year. In order for calendars to maintain their consistency with this orbit, every 4 years one day is added – this is called a leap day – as well as a leap year.
Earth’s orbital speed averages 29.78 km/s (107,208 km/h; 66,616 mph), which is fast enough to cover the planet’s diameter in 7 minutes and the distance to the Moon in 4 hours.
To know about Mercury https://www.knowledgebeach.com/mercury-nine-planets-in-universe/