SPACE AND ASTRONOMY

SPACE AND ASTRONOMY

SOLAR SYSTEM

People have been watching the sky

for thousands of years and

wondered exactly what is out there.

With advances in telescopes as well

as spaceships which have physically

 traveled to various planets, a

considerable amount of knowledge

 has been obtained to better

understand the universe near to us.

The name of our system comes from the old latin word for the Sun: Sol. Because the Sun is the largest object in the system and all the other bodies orbit around it, it became known as the Solar system.

Who discovered it? 

Prior to 1781, there were only seven known bodies in our solar system, besides the Earth. These seven were the Sun, our Moon, Mercury, Venus, Mars, Jupiter, and Saturn. These had been known since humans first began to observe the sky at night. There were also visitors called comets that would appeared in the sky for a time, then fade away. 

Who discovered it? 

Galileo Galilei first turned a telescope on the sky and began to write down what he saw. Among the things he saw were four moons orbiting Jupiter. As time passed and the telescope was improved, more objects were found. In 1655, Christiaan Huygens discovered the moon Titan orbiting Saturn. In 1781 Sir William Herschel discovered the planet Uranus. In 1801, Giuseppe Piazzi discovered the first asteroid. Many more asteroids were later discovered by astronomers. The discovery of the planet Neptune did not come by chance, but was found using math.

The Sun

The Sun is a large ball of very hot gas, mostly hydrogen and helium. It is

the power house of the Solar System. It's our nearest star. Scientists can tell what is going on inside a star from its color. Without the sun there would be no life on Earth. 

How big is the sun?

 

The Sun is very big - much, MUCH bigger than the Earth! It is 1,392,000 km or 109 Earths across and contains more than 99.9% of the solar system's mass. If you could somehow stand on the surface of the Sun, you would weigh 28 times as much. A grown person would weigh as much as a car. More than a million Earths could fit into the volume of the sun! It doesn't look that big from where we stand, though. That's because the sun is about 150,000,000 km away. At that distance, it takes light from the sun over eight minutes to reach the Earth. 

Mercury

Mercury is about 4879 km in diameter, which makes it a little over a third as big as the Earth is across. It's small enough that eighteen balls of modeling clay the size of Mercury could be rolled together to make one the size of Earth. In fact, the diameter of Mercury is only about one and a half times the diameter of our moon. It is the second smallest planet in the Solar System, just larger than Pluto. The small size and how close it is to the Sun sometimes make it difficult to observe Mercury in the sky, especially without a telescope or binoculars.

Venus

Venus is the second closest planet to the sun, and was named after the Roman goddess called Venus. It is in a category called terrestrial planets, this means that it is very similar in size and was created close to the same way as our planet Earth. In fact, sometimes it is called Earth's "sister planet" as they are somewhat alike in both size and roughly a similar distance from the sun.

Earth

Earth is the planet we live on. It is the only planet in the solar system with liquid water. It's also the only one known to have Scientific evidence shows that the Earth is 4.6 billion years old. Earth's surface is made of continents and oceans. There are also islands in the oceans. The top layer of Earth is called the crust. It divided into pieces called tectonic plates. They move very slowly, carrying continents with them.

Moon

The Moon is Earth's only permanent natural satellite.

Twelve people landed and walked on it in the 1960s and 1970s. They collected and brought back rocks that were studied to find more about the Moon

Mars

Mars is the fourth planet from the sun. It is a terrestrial planet, because it is very similar to the Earth in terms of atmosphere and

surface features.

Jupiter

Jupiter is by far the largest planet within our solar system: two and a half times larger

 than all of the other planets put together. It is the fifth planet from the Sun and one

of the brightest planets. Jupiter is sometimes called a "gas giant“ because most of this planet is made up of liquid and gas.

Saturn

Saturn is 120,536 km or 9.449 Earths in diameter at the equator. It is only 108,728 km or 8.552 Earths in diameter from pole to pole. It is bigger at the equator because it spins fast enough to budge out.

Uranus

Uranus, the seventh planet from the sun, was discovered by William Herschel on March 13, 1781. It is a gas giant and the third largest planet in the Solar System.

Neptune

Neptune is very similar to Uranus, but it is slightly smaller in diameter and more Massive Neptune has a diameter of 49,528 km across at the equator and 48,681 km from pole to pole. It is almost as big as four Earths in a row. It bulges out a little at the equator because of its rotation, but not as much as Jupiter and Saturn.

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