HOW FAST DOES EARTH GO ROUND THE SUN?

Earth's average orbital speed is about 30 kilometers per second. In other units, that's about 19 miles per second, or 67,000 miles per hour, or 110,000 kilometers per hour (110 million meters per hour).

Let's calculate that. First of all we know that in general, the distance you travel equals the speed at which you travel multiplied by the time (duration) of travel. If we reverse that, we get that the average speed is equal to the distance traveled over the time taken.

We also know that the time it takes for the Earth to go once around the Sun is one year. So, in order to know the speed, we just have to figure out the distance traveled by the Earth when it goes once around the Sun. To do that we will assume that the orbit of the Earth is circular (which is not exactly right, it is more like an ellipse, but for our purpose a circle is close enough). So the distance traveled in one year is just the circumference of the circle. (Remember, the circumference of a circle is equal to 2×?×radius.)

The average distance from the Earth to the Sun is about 149,600,000 km. (Astronomers call this an astronomical unit, or AU for short.) Therefore, in one year, the Earth travels a distance of 2×?×(149,600,000 km). This means that the speed is about:

speed = 2×?×(149,600,000 km)/(1 year)

and if we convert that to more meaningful units (knowing that there are, on average, about 365.25 days in a year, and 24 hours per day) we get:

speed = 107,000 km/h (or, if you prefer, 67,000 miles per hour)

So the Earth moves at about 110,000 km/h around the Sun (which is about one thousand times faster than the typical speed of a car on a highway!)

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WHAT DID EARLY EARTH LOOK LIKE?

At the start, it was just a fiery ball of molten (liquid) rock. As it cooled, lumps formed on the surface of the molten rock. The surface gradually hardened into a crust. Volcanoes kept on pouring steam and gases onto the surface, which led to the atmosphere being formed. As Earth cooled further, clouds of steam became water, creating vast oceans. The crust eventually cooled to form the continents.

Three recent studies improve our understanding of environmental conditions on early Earth—important not just for reconstructing the history of our own planet, but for assessing the habitability of planetary bodies in general.

The first of these studies was led by John Tarduno from the University of Rochester and reported in Proceedings of the National Academy of Sciences. The authors present evidence of a strong magnetic field around Earth, from about 4.1 billion to 4 billion years ago. Their conclusion is based on magnetite inclusions in certain minerals (zircons), and thus appears to be very reliable. A strong magnetic field would have been critical for life to originate on Earth, because it would have protected the surface from the solar wind. Stars like our Sun are known to expel large amounts of harmful radiation when they are still young, and without a magnetic field it is doubtful life on Earth’s surface would have been able to survive the barrage.

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WHAT IS THE SHAPE OF EARTH?

Earth is not quite a perfect sphere. The spinning of the planet causes it to bulge at the equator. Scientists describe Earth’s shape as ‘geoid’, which, interestingly, means ‘Earth-shaped’.

The shape of the Earth is geoid.

Earth looks like a blue marble with white swirls and areas of brown, yellow, green and white from space.

  • The blue is water, which covers about 71 per cent of Earth’s surface.
  • The white swirls are clouds. The areas of brown, yellow and green are land.
  • The areas of white are ice and snow.

Scientists use geodesy, which is the science of measuring Earth’s shape, gravity and rotation. Geodesy provides accurate measurements that show Earth is round. Even though our planet is a sphere, it is not a perfect sphere. Because of the force caused when Earth rotates, the North and South Poles are slightly flat.

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WHAT MAKES EARTH UNIQUE?

Earth is the only planet in our Solar System with oxygen in its atmosphere and lots of liquid water on its surface, allowing life, in its various forms, to exist. It is our beautiful blue planet, thriving with a multitude of living animals, plants and, of course, human beings!

In the solar system, the Earth is the third planet from the sun, and it is the only planet known to have life. According to different sources of evidence like radiometric dating, the Earth is believed to be more than 4.5 billion years old. Out of the four terrestrial planets, the Earth is the largest and densest planet. The lithosphere is made up of numerous tectonic plates that keep moving over millions of years. Water in the oceans cover about 71% of the total surface of the Earth, and the remaining 29% is covered by the continents and islands, which have rivers and lakes. The ability of the Earth to harbor life makes the Earth a unique planet in the solar system, and this stems from the fact that water in liquid form exists on the planet. Similarly, the existence of gaseous oxygen in the atmosphere of the Earth also supports life.

credit: worldatlas

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HOW DID EARTH BEGIN?

Scientists think Earth was formed at roughly the same time as the Sun and other planets when the Solar System came together from a giant, rotating cloud of gas and dust known as the solar nebula. As the nebula collapsed because of its gravity, it spun faster and flattened into a disc. Most of the material was pulled towards the centre to form the Sun. Gradually, the rest of this vast cloud began to cool and the gas condensed into trillions of droplets. These droplets were slowly pulled together by their own gravity and formed clumps. Leftover particles within the disc collided and stuck together to form other larger bodies, including Earth.

When Earth formed 4.5 billion years ago, it was a sterile ball of rock, slammed by meteorites and carpeted with erupting volcanoes. Within a billion years, it had become inhabited by microorganisms. Today, life covers every centimetre of the planet, from the highest mountains to the deepest sea. Yet, every other planet in the solar system seems lifeless.

Many ideas have been proposed to explain how life began. Most are based on the assumption that cells are too complex to have formed all at once, so life must have started with just one component that survived and somehow created the others around it. When put into practice in the lab, however, these ideas don’t produce anything particularly lifelike. It is, some researchers are starting to realise, like trying to build a car by making a chassis and hoping wheels and an engine will spontaneously appear.

Credit: newscientist

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