THE SOLAR SYSTEM
AND EXPLORING SPACE
Our Solar system includes everything affected by the Sun's gravitational pull. It includes the Sun at its centre, as well as everything orbiting around it: eight planets and numerous other objects, such as moons, asteroids and comets.
Scientists found evidence that there may be a very large, ninth planet beyond Neptune, by tracking its gravitational pull -- but no one has spotted it yet!
Before we start checking out our Solar System's planets and seeing their different and unique stats, it's a good idea to talk about some of the terms we might hear.
You know what is temperature, pressure, axis; but do you know what is equinox, aphelion and periphelion? Watch the video below to find out.
You know what is temperature, pressure, axis; but do you know what is equinox, aphelion and periphelion? Watch the video below to find out.
So, Aphelion is the point when a planet is the furthest from the Sun, while Periphelion is the point when a planet is closest from the Sun.
The Planet that Was
Before we hit the eight planets that are, let's take a brief moment to acknowledge the little planet that was - Pluto!
Since 2006, Pluto has lost its planet status. It's been a long time now -- longer than all of you have been alive -- but it's still pretty sad for us older people. It does show, however, that science is always evolving and changing, and as you know more, you can always update the science!
Since 2006, Pluto has lost its planet status. It's been a long time now -- longer than all of you have been alive -- but it's still pretty sad for us older people. It does show, however, that science is always evolving and changing, and as you know more, you can always update the science!
Let's review!
What are the three conditions for a celestial body to be called a planet?
After the discovery of the Kuiper belt, and after noticing that Pluto's gravitational pull was not able to clear an area around it from the small glass objects, it made more sense to consider Pluto not as a planet, but the biggest Kuiper Belt object.
What are the three conditions for a celestial body to be called a planet?
- It must orbit a star (in our cosmic neighborhood, the Sun).
- It must be big enough to have enough gravity to force it into a spherical shape.
- It must be big enough that its gravity has cleared away any other objects of a similar size near its orbit around the Sun.
After the discovery of the Kuiper belt, and after noticing that Pluto's gravitational pull was not able to clear an area around it from the small glass objects, it made more sense to consider Pluto not as a planet, but the biggest Kuiper Belt object.
Birth of the Solar System
How did the Solar System appear? Let's find out! Watch birth of the solar system here!
THE OUTER PLANETS
The OUTER PLANETS of the Solar system are the planets that are farthest from the Sun. The outer planets are all called gas giants, because although they have rocky or metallic cores, they are mostly made of gassy sludge. Gas giants don't have defined outlines and are much larger than the terrestrial or inner planets.
Neptune
- Farthest planet from the Sun
- Bluish-green in colour
- Atmosphere can change rapidly, with powerful wind storms that break the sound barrier
- Has at least 13 moons and many space dust rings
- Neptune is the only planet in our Solar system that we can't see with the naked eye.
- A day in Neptune is pretty short, only 16 hours -- but each year takes 165 Earth years to complete!
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Uranus
- Bluish-green in colour, caused by methane in its atmosphere
- Atmosphere is hydrogen, helium and methane
- Has at least 27 moons
- Probably mostly ice and rock
- It spins in the opposite direction as the Earth
- Uranus is flipped on its side, as if standing on its rings. This position is very, very unusual, and would not have happened normally!
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Saturn
- Second largest planet, with the lowest density
- Mostly hydrogen and helium
- has a complex system of rings, which are made of ice, rock particles and space dust
- Has at least 60 moons (and one of the moons has active volcanoes!)
For a long time, scientists thought Saturn was the only planet with rings. Since the 70s, with better telescopes and tools, it became known that many planets have rings, not just Saturn. In fact, every single one of the giant gas planets -- Jupiter, Saturn, Uranus and Neptune -- have rings. The thing that makes Saturn's rings different is the way in which they were formed... as well as how visible they are. Let's find out more!
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Watch Saturn - The Moon King
Jupiter
- Largest planet in the Solar system
- Made mostly of hydrogen, helium, ammonia, methane, and water vapor
- Has at least 66 moons, including the largest moon in our solar system
- has white, red and brown stripes, which are gas storms. The Great Red Spot (a giant red spot permanently on the surface) is a huge storm.
- Mass: 318 Earths
- Orbital speed: 13.06 km/s
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THE INNER PLANETS
The four planets closest to the Sun are called the INNER PLANETS. All of the Inner planets are TERRESTRIAL PLANETS, which means "earthlike". The terrestrial planets are made of rocks and have iron cores, just like Earth. Many of the inner planets have craters, or holes on their surfaces, caused by rocks smashing into them. These are the inner planets (in order from furthest to the Sun to the closest) and their characteristics:
Mars
- Looks red because it contains iron oxide (rust)
- Has ice caps and rift valleys and the largest volcano in the Solar system, Olympus Mons
- Has a thin atmosphere that is mostly Carbon dioxide
- Has huge dust storms and seasons
- Has two small moons, Phobos and Deimos
- Mass: 0.107 Earths
- Orbital speed: 24.07 km/s
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Wow! Water on Mars!!!
But wait... to actually reach it, humans would have to dig 15 to 20 kilometers deep in order to reach it.
How could we go about getting to the water? Talk on your table about this!
But wait... to actually reach it, humans would have to dig 15 to 20 kilometers deep in order to reach it.
How could we go about getting to the water? Talk on your table about this!
Earth
- This old dirt ball that we take for granted
- Only planet known to support life, helped by its unique properties such as liquid water, atmosphere, our magnetic field and an ozone layer
- Has one large moon
- Mass: 1 Earth (ha ha), or 5.972X10^24 kg
- Orbital speed: 29.78 km/s
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Earth's Moon
After the Sun, the Moon is the most important celestial body for the Earth. It affects our tides, the light at night, and many have considered that it may even affect human and animal behaviour, perhaps due to melatonin fluctuations. What do we know about the Moon? Let's see a few facts!
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Venus
- Close in size and mass to planet Earth
- Has a dense atmosphere of mostly Carbon Dioxide that collects heat, keeping the planet around 464C
- Mass: 0.815 Earths
- Orbital speed: 35.02 km/s
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Mercury
- Has extreme temperatures (-180C to 430C) because it has no atmosphere
- Looks like Earth's moon, with many cliffs and craters
- Has no moons
- Mass: 0.055 Earths
- Orbital speed: 47 km/s
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The Sun
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Watch Voyage into the Sun
Other objects in the Solar System
Besides planets and moons, there are other objects in our solar system:
Asteroids: Huge chunks of irregularly shaped rocks. They can be found mostly in separate areas of our Solar system (thank goodness!)
We have a disk-like ASTEROID BELT between Mars and Jupiter, as well as two donut-shaped structures called Kuiper Belts. These giant donuts are mostly formed by asteroids. More on Kuiper belts later!
Comets: dirty snowballs made of dust, rock particles, frozen gases, and ice that are orbiting the Sun, usually with enormous orbits. They can take years and years to return. They are sometimes visible to the naked eye when they pass through the inner Solar system because of their long tails -- caused when they are partly vaporized by the Sun (the tail does not follow behind the comet, it always points toward the Sun!)
Oort cloud: A cloud of billions of comets beyond Pluto, named after astronomer Jan Oort, who first proposed the model. More about Oort clouds later!
Meteoroids, Meteors, Meteorites: Meteoroids are small pieces of rock and dust. They become meteors (shooting stars!) when they enter the Earth's atmosphere and burn from all of the atmosphere friction into a bright and hot streak. Most meteors burn out and never reach the Earth; the ones that makes it to Earth without turning into dust are called meteorites, and some people like to collect these.
Asteroids: Huge chunks of irregularly shaped rocks. They can be found mostly in separate areas of our Solar system (thank goodness!)
We have a disk-like ASTEROID BELT between Mars and Jupiter, as well as two donut-shaped structures called Kuiper Belts. These giant donuts are mostly formed by asteroids. More on Kuiper belts later!
Comets: dirty snowballs made of dust, rock particles, frozen gases, and ice that are orbiting the Sun, usually with enormous orbits. They can take years and years to return. They are sometimes visible to the naked eye when they pass through the inner Solar system because of their long tails -- caused when they are partly vaporized by the Sun (the tail does not follow behind the comet, it always points toward the Sun!)
Oort cloud: A cloud of billions of comets beyond Pluto, named after astronomer Jan Oort, who first proposed the model. More about Oort clouds later!
Meteoroids, Meteors, Meteorites: Meteoroids are small pieces of rock and dust. They become meteors (shooting stars!) when they enter the Earth's atmosphere and burn from all of the atmosphere friction into a bright and hot streak. Most meteors burn out and never reach the Earth; the ones that makes it to Earth without turning into dust are called meteorites, and some people like to collect these.
Your Solar System Project
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For this project, your group will create a model of the solar system, and select one of the planets to highlight.
You must research everything about the planet, and present your model to the class, as well as all you have discovered about your planet. |
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Above, you can see a SCALE MODEL of the Solar system. A scale model is a representation of an object that is usually smaller than the original.
You can see that the sizes are to scale, however the distance between the planets is not; it would be impossible to make a model that would be to scale both in size and distance, due to the size of the Solar system.
You can see that the sizes are to scale, however the distance between the planets is not; it would be impossible to make a model that would be to scale both in size and distance, due to the size of the Solar system.
