# data[].attributes.body
THE SUN IN THE MIDDLE

# data[].attributes.attachment_link.readable_text
Everything in the Solar System orbits around the Sun. It's mass is greater than all of the other planets combined. Even though the Sun is huge, it is small when compared to other stars in the galaxy. Even though it is smaller, the Sun provides all of the light for the Solar System. As far as astronomers are concerned, our Sun is named Sol. The entire group of Sun and planets is called the Solar System. If another star were named Andros, that system would be named the Androsian System.

There is a core to the Sun as there are in planets. Stars are different because most of that central mass is made of tons and tons of hydrogen (H) and helium (He). The hydrogen is constantly involved in the fusion reactions, which produce extreme amounts of energy (light, heat, radio waves). Did you know that our Sun used to be hotter? Astronomers now classify it as a G2 star. It is middle-aged and starting to cool and die. Don't worry. It's going to take millions of years for it to burn out. For example, a G5 star is very old and close to death.

The Sun has different layers in its atmosphere, just like the Earth. Don't get excited, you aren't going to be able to breathe on the Sun. The layers of the atmosphere are huge, swirling masses of plasma at extremely high temperatures. Surrounding the core is a radiative level of plasma. Reactions happen in that layer and churn/stir the next layer, the convective layer. Large amounts of interaction occur in the convective layer. It's constantly spinning the way storms spin on Earth. The outer layer of the Sun's atmosphere is the photosphere. When scientists use special telescopes to look at the Sun, this is the layer they can see.

Everything on Earth is affected by the Sun. The Earth's orientation to the Sun creates the seasons of the year. When your hemisphere of Earth is directed away from the Sun, it is winter. When your hemisphere is pointed closer to the Sun, it is summer. So when you're in the Northern Hemisphere and it's summer, kids in Australia might be skiing. As you learn more about the other planets in the Solar System, you will discover that the same idea works for most of them.

The Sun's energy is spread around the planet, but is focused on or near the equator. That centerline of the planet is where you will find long sunny days, very little seasonal change, and the warmest ocean waters. From the equatorial regions, energy moves north and south as it circulates around the planet. That circulation can happen in the atmosphere or the oceans.

# data[].attributes.attachment_link.description
Everything in the Solar System orbits around the Sun. It's mass is greater than all of the other planets combined. Even though the Sun is huge, it is small when compared to other stars in the galaxy. Even though it is smaller, the Sun provides all of the light for the Solar System.

# data[].attributes.body
MORE THAN PLANETS

# data[].attributes.attachment_link.readable_text
Did you know that the Earth is constantly bombarded with pieces from the Sun? They aren't rocks and flames. The Sun is sending very small particles (usually protons and electrons) into the Solar System. Those particles are called the solar wind. The flow of particles doesn't just go to Earth. The particles hit all of the planets in the Solar System and create an envelope that protects the system.

The heliosphere is not something you can touch like a planet or a comet. It is an area around the Solar System that is filled with particles given off by the Sun. Those particles and related magnetic fields are called the solar winds. The solar winds move through the heliosphere until they reach the edge called the heliopause.

Astronomers think that the asteroids are leftover pieces of the Solar System. As other large objects in the system combined to form planets, there were some smaller pieces left over. Their location between Mars and Jupiter could also influence the pieces. They may have never formed a small planet because of the gravitational pulls of Jupiter (very strong) and Mars (very weak). The pulling of the two planets keeps the asteroids separated and circling the Sun in a doughnut shaped area.

# data[].attributes.attachment_link.description
Did you know that the Earth is constantly bombarded with pieces from the Sun? They aren't rocks and flames. The Sun is sending very small particles (usually protons and electrons) into the Solar System. Those particles are called the solar wind. The flow of particles doesn't just go to Earth.

# data[].attributes.body
THE SOLAR SYSTEM

# data[].attributes.attachment_link.readable_text
If you remember anything about Mercury, remember that it is the closest planet to the Sun and really hot. Temperatures on Mercury get up to 460 degrees Celsius. An average temperature on Earth is about 15 degrees Celsius (although it has a wide range). The Sun beats down on little Mercury all day long.

The amazing thing is that there is a side of Mercury that faces away from the Sun. Temperatures on the dark side of the planet can drop to less than negative 180 degrees Celsius. It's a whopping 640 degree temperature change from the hottest to the coldest part of the planet. The temperature ranges are a direct result of the very long days on Mercury. It takes 58 Earth days for Mercury to complete one of its days. This slow rotation affects the temperatures on the surface. Very long days allow the temperature to build for long periods of time.

The second planet away from the Sun is called Venus. It's ironic that Venus is named after the Roman goddess of love and beauty. Venus is one of the harshest planets in the Solar System. It's over 460 degrees Celsius. It has clouds of sulfuric acid in an atmosphere of carbon dioxide. Lava is found across the surface after being spewed from volcanoes. While a harsh place for you, scientists think it's an amazing planet.

The third planet from the Sun is your home. The 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. We have a very narrow temperature range that allows water to remain a liquid. Life has developed over millions of years because of that liquid. What else makes us special? Most of our atmosphere is made of nitrogen (N), a relatively inert gas. If we had clouds of sulfuric acid or methane (like other planets), life may have never developed.

Mars is the fourth planet from the Sun. It is a very active planet like the Earth. It has evidence of volcanoes, plate tectonics, and liquid water (as opposed to ice) on the planet. It even has polar ice caps like the Earth, with water in the north and solid carbon dioxide in the south. With all of these similarities, Mars is still nothing like Earth. It only has 40% of our gravity because the mass of the planet is so much smaller. Also, its atmosphere is made up of carbon dioxide and has less than 1% of the atmospheric pressure of Earth.

Jupiter is the largest planet in our Solar System. Its mass is over 300 times the mass of the Earth. If you look at its atmosphere and over 20 moons, you could say that Jupiter is almost like another Sun. There is only one thing missing -- Heat. There is a magical time in a star's life when nuclear reactions start and the star begins to burn. Jupiter never got to that point.

Jupiter is classified as a Jovian planet. The Jovian planets are gas giants that orbit the Sun. Gas giants don't have solid surfaces of rock like other planets. You will find some rock at the core of the planet, but it is very little when compared to the planet as a whole. As you move deeper into the planet, you find very dense gases that have become liquids. All of the Jovian planets are huge compared to the Earth but tiny when compared to the Sun. Jupiter has a diameter of 85,000 miles while Earth is only 7,600 (the Sun is about 870,000 miles). Jupiter is often one of the brightest objects in the sky because of its size.

Saturn is the other big planet in our Solar System. You will find its orbit just outside of Jupiter in the sixth position. It is a gaseous planet like Jupiter and those gases give Saturn a very low density. The big astronomy joke is that if you could find a lake big enough and put Saturn in the water, it would float. Its density makes it lighter than water. While knowing Saturn's density is a fun fact, we know that the thing you will remember is that Saturn is the planet with the big rings. While other planets in our Solar System have rings, Saturn's can be seen from Earth. The Cassini spacecraft is studying the moons and rings of Saturn for several years.

The seventh planet from the Sun is Uranus. William Hershel discovered it in 1781. It is one of the four gas giants in our Solar System, but is much smaller than both Jupiter and Saturn. You will find that Uranus is similar in some ways to Neptune, the eighth planet. Only one Voyager probe has flown by Uranus so very little is known about the planet.

Like other planets we discussed, Uranus is a planet largely composed of gases. It has a light blue color because of the methane in its atmosphere. The atmosphere of hydrogen, helium, and methane is constantly swirling around the planet. As you move from the core to the surface of the atmosphere, you will discover liquid rock, ice, and molecular hydrogen. There is no layer of metallic hydrogen like Jupiter and Saturn.

Neptune is the eighth planet form the Sun. It wasn't discovered until 1846. It wasn't even actually seen with a telescope for several years after that. Astronomers noticed some funny movements in the orbit of Uranus. The changes in the expected orbit were so large than they decided another planet must exist. They made the calculations, looked in the right place, and found Neptune.

Neptune is huge in size compared to Earth. When you compare it to the other gaseous planets like Jupiter and Saturn, it is the smallest. Like the other Jovian giants, Neptune's atmosphere is made up of hydrogen and helium. It also has large amounts of methane that give it a deep blue tint. It is very similar to Uranus.

See that big swirl in the atmosphere? Just like Jupiter, Neptune has large storms swirling in its atmosphere. When Voyager II passed by, it took pictures of a storm that was big enough to hold the Earth. The storm was moving at more than 500 miles per hour. The speeds inside of the storm could have been more than seven times the speed of the fastest winds on Earth.

We didn't even know that Pluto existed until the 1930's. Astronomers studied the orbit of other planets in the area and noticed a little wobble. The wobble was big enough for astronomers to start looking for a source. Eventually Clyde Tombaugh found Pluto. In recent years, additional large bodies have been discovered just beyond Pluto's orbit.

For such a small object, there is a lot of debate about Pluto. Its size is one of the big reasons that astronomers stated that it is no longer considered a true planet. The International Astronomical Union (IAU) met in August 2006 and decided that Pluto would be classified as a dwarf planet. The change comes because of Pluto's size and eccentric (strange) orbit. It passes in an out of the orbit of Neptune and doesn't orbit in the same plane as the other planets. It's a weird little object. Astronomers decided that this weird little object would no longer be a planet. Even though a small object, Pluto has its own satellite (moon) named Charon.

# data[].attributes.attachment_link.description
If you remember anything about Mercury, remember that it is the closest planet to the Sun and really hot. Temperatures on Mercury get up to 460 degrees Celsius. An average temperature on Earth is about 15 degrees Celsius (although it has a wide range). The Sun beats down on little Mercury all day long.

# data[].attributes.body
ALGUNOS SISTEMAS SOLARES

# data[].attributes.attachment_link.readable_text
http://nineplanets.org/
Tomorrow we will read about planets. Here you are a wonderful page. I hope you enjoy yourself!

If you like planets you can find solar systems made by fifth graders of our school.
Congratulations children!

# data[].attributes.attachment_link.description
http://nineplanets.org/ Tomorrow we will read about planets. Here you are a wonderful page. I hope you enjoy yourself! If you like planets you can find solar systems made by fifth graders of our school. Congratulations children!

# data[].attributes.body
VIDA Y MUERTE DE UNA ESTRELLA

# data[].attributes.body
LA ROTACIÓN Y LA TRANSLACIÓN

# data[].attributes.body
EL SISTEMA SOLAR