What do we know about our planet (I)?

At first, Earth is the only known planet where life can survive. As far as we know, there is no other planet in the universe like Earth.

The planet Earth is made of stardust, born together with the Sun and the other planets. They were formed about 4.5 to 4.8 billion years ago. Once upon a time, billions of years ago, there was a whole bunch of atoms floating around the universe. Slowly those atoms and molecules came together and formed what we call ‘Earth’.

Now Earth is a big ball of matter that circles the Sun once a year or 365 and a quarter days. So, the collection of quarters throughout four years forms a Leap Year. There are 366 days in it.

Our planet is about 5 billion years old and we have things with the same age! They are St. Peter and St. Paul. They are about 4 billion years old. Of course, they are not humans, but the oldest rocks lying in the Atlantic Ocean.

Earth is a high speed vehicle and it drives round the Sun. The orbital speed of our planet is about 30 km/s (107,200 km/h) in average.

In addition, our solar system with 8 planets, including our planet Earth-whirls around the center of our galaxy. And it is even speedier highway - 220 kilometers per second, or 792,000 per hour.

We know that our planet is the third planet from the Sun. And as all celestial bodies, it has a sign. The astronomical sign for the planet is a circle with a cross inside.

Our planet is rather heavy; its mass is 6 sextillion tons (6x1021).

The total surface area of Earth is about 510 million square km.

Area of land: 148 million square kilometers, it is 29 percent of the total surface of the planet Earth.

Area of water: 361 million square kilometers, it is 71 percent of the total surface of our planet.

97 percent is salt water and only 3 percent is fresh water.

Today there are more than 7 billion human beings, inhabiting the planet.

Did you know that the Sun lies about 150 million kilometers away from us?

This distance between the Earth and the Sun is called an Astronomical Unit (AU).

The astronomical unit provides a convenient way to express and relate distances of the objects in the solar system. It helps astronomers to carry out various astronomical calculations. For example, Jupiter is 5.2 AU (5.2 Earth distances) from the Sun and Pluto is nearly 40 AU.

So, we are really far from the Sun. And the following fact proves it. Did you know, that it takes about 8 minutes for sunlight to reach us – even when it is travelling at about 3,000,000 kilometers per second? This means that we see the Sun set eight minutes after this event has actually taken place!

How to understand the size of our planet Earth in comparison with other planets in our Solar System?

Is it big enough or not really? To realize the actual size of our planet in space, let’s take something familiar to us, something that we can see every day. What about food? Let’s take for this experiment different fruits and vegetables!

If we do so, then Mercury becomes a peppercorn, and Venice – a very big blueberry. Our planet Earth can be a tomato-cherry, and Mars – a green pea. Jupiter is the biggest planet in our Solar System, and watermelon is the biggest fruit I know. Saturn then will look like a grapefruit and Uranus – like an apple. And we take a lime to make an example for Neptune.

Did you know that…

1. Earth is the only planet in Solar System to have water in its three states of matter: as a solid (ice), a liquid (sea, rain, etc.) and as a gas (clouds).

2. Earth is the only planet that has an atmosphere containing 21 percent oxygen. That why we have a life on our planet and thanks to that we can breathe.

3. A British astronomer Fred Hoyle was the first to point out that if you could drive a car upwards at 95km/h (60mph), it would only take about an hour to get into space. To get to the Moon would take a little longer though, just under six months. (Citation: Space isn't remote at all. It's only an hour's drive away if your car could go straight upwards).

4. It’s been estimated that there are more stars in the Universe than there are grains of sand on Earth, but there are more atoms in one grain of sand than there are stars in the Universe.

Did you know that…

The National Aeronautics and Space Administration (NASA) is already making the necessary preparations for the expedition to planet Mars. I mean a human expedition.

But who will make it as the first human to walk on the Red Planet?

Actually, it is Alyssa Carson who hopes to be the first person to see and explore Mars in person. She has been spending years making preparations for this journey in 2033. She decided to become an astronaut when was 3-years old.

"I would love to go to Mars because it is a planet that no one has been before," Carson wrote on her website. "It's about the same size as the Earth and there are ice caps at the top and bottom of Mars. That means there is water on Mars. This could possibly be our next Earth."

Even NASA officials think that Carson has a good chance of making it to the Red Planet.

Do you think it’s something impossible? Do you really think that Mars is far far away from us?

Well, Mars can be closer than one can think of. Some pieces of rock that fell to Earth from space are indeed from planet Mars. New data collected by NASA's Mars rover Curiosity helped confirm the origins of some meteorites. And they are from Mars.  So, spaceflights are too expensive, but everyone can do some easier things – find Mars and Moon rocks lying on the ground on Earth.