The Solar System
Maps of the Solar System
Below are 4 maps of the solar system.
Below are 4 maps of the solar system.
From these maps you should remember that the solar system is made up of:
Order of the Planets
- The Sun
- planets
- asteroid belts
- comets
- minor planets like Pluto
Order of the Planets
The Order of the Planets is as seen above:
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
Why is Pluto not a planet?
Size of the Planets
You need to remember the order of the planets in SIZE from largest to smallest:
You need to remember the order of the planets in SIZE from largest to smallest:
Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury
Above shows a slideshow of images of the planets relative sizes.
Below shows a table of the sizes (diameters). The unit we use is 'Earth diameters' instead of metres, where 1 Earth Diameter = the diameter of Earth.
Below shows a table of the sizes (diameters). The unit we use is 'Earth diameters' instead of metres, where 1 Earth Diameter = the diameter of Earth.
Periods of the Planets
The Earth takes around 365 days to make one full orbit around the sun. The time it takes for a planet to go around the sun is known as its Period. The Period of the Earth is 365.24 days.
The closer you are to the Sun, the shorter your period. Not only is your orbit smaller and thus you have less distance to travel, you also feel the Sun’s gravity more strongly and so have to move faster in order not to get dragged into the sun.
Hopefully you see that Mercury not only has the smallest distance to traverse on its orbit… it also moves the fastest. As you move further out, the orbits get bigger AND the speeds get slower.
The following table gives the periods of the 8 planets. The unit of time used is number of Earth days and/or Earth years.
The following table gives the periods of the 8 planets. The unit of time used is number of Earth days and/or Earth years.
Distances from the Sun
The planets move around the sun in orbits that are almost circles but are actually ellipses (stretched out circles). The distances are therefore not constant. However, we can give average distances.
Since we are dealing with such large distances, instead of dealing in m or km we deal in a UNIT OF LENGTH called AU (Astronomical Unit). 1 AU = the average distance between the Earth and Sun. Jupiter is roughly 5 AU away from the sun. This means it is 5 times further away from the sun than the Earth is. Saturn is 9.6 AU. This means it is 9.6 times further away from the sun than the Earth is. Venus is 0.72 AU. This means if you went from the sun to Venus, you are 72% of the way to Earth, and still have 28% of the journey to go.
Below is a scale diagram of the planet’s average distances from the sun. We let 1 cm = 1 AU and work from there. M = Mercury, V = Venus, E = Earth, M = Mars.
A table of the planets and their average distances from the sun are given below:
Mass
The slide show below will give you an idea of how mass in the solar system is distributed:
If we let 1 “Earth” represent the mass of the Earth, then we can define the masses of the other planets as follows:
Number of Moons
Did you know Mercury and Venus have no moons! And Mars only has 2 tiny potato shaped asteroids (about the size of a city) that it captured and turned into its moons. Earth has 1 moon. But the larger planets of the outer solar system all have multiple moons with Jupiter having the most. Below is a list of the number of confirmed moons (with relatively stable orbits) for each planet. More moons may be discovered but they will only be small ones.
Most moons are actually very small. There are 7 largish moons: the 4 Galilean Moons of Jupiter (Io, Europa, Ganymede, Callisto - that can be seen with binoculars), Titan of Saturn, Triton of Neptune, and Earth’s Moon. Every other moon is significantly smaller. The pie chart below shows the relative masses of the 19 biggest moons. As you can see, the 7 most massive moons are much larger than any other moon.
Life in the Solar System
As far as we can tell, the only life in the Solar System is on Earth. Life, as we understand it, needs liquid water to survive.
It is possible that microbial (simple) life exists elsewhere in the solar system. Astrobiologists look for places in the solar system that have liquid water when looking for life.
The 2 most likely places of life are:
As far as we can tell, the only life in the Solar System is on Earth. Life, as we understand it, needs liquid water to survive.
It is possible that microbial (simple) life exists elsewhere in the solar system. Astrobiologists look for places in the solar system that have liquid water when looking for life.
The 2 most likely places of life are:
- Mars (underneath the surface may be liquid water - we have detected frozen water at the poles and know water was once on the surface)
- Europa - moon of Jupiter (an ice world, we believe beneath the ice is a liquid ocean. Tidal forces from Jupiter could be enough to heat the inner part of the planet and allow life to exist in the underground oceans. Problem is, we have never landed on Europa to drill through the ice and check. Maybe one day we will.
Formation of the Solar System
Why does everything in the solar system spin the same way?
Every planet in the solar system all orbits in the same direction along its orbit... counterclockwise (when you view the solar system ABOVE the north pole of Earth). But why? What forced it to be so orderly?
Well, we know the solar system began as just a cloud of gas and dust, made up of particles all moving in their own paths within the cloud. As the cloud collapsed (with MOST of the stuff falling into the centre to form the SUN), there WAS some chaos with things moving in all sorts of directions. However, one particular direction had just a slight dominance over the other directions. And through collisions, opposite directions would cancel out. At the end of it all, what was left was the dominant direction. The video below demonstrates this:
Why is the solar system flat?
If the solar system formed from a gas cloud where all the atoms where flying around in different ways, then why don't the planets all move around in totally different orbits in 3D like the image below?
The following video explains WHY our solar system does NOT look like this:
Death of the Sun and the Fate of Earth
How Does a Planet Stay in Orbit if the Sun's gravity is pulling it towards the Centre?
The trick to orbiting around a Sun (or planet or whatever) is to move with the right SPEED.
If you drop a ball, it has no initial horizontal speed, and gravity clearly pulls it to the center of the Earth. No orbit there!
Now consider shooting a cannonball horizontally off a cliff. The cannonball will make some progress is moving sideways before gravity pulls it to the ground. However, if we could shoot the cannonball with enough speed, it would 'FALL' at the same rate as the Earth curves, and so never actually get closer to the ground. Thus, it would keep "falling" forever and it went around and around. This is essentially what an orbit is.
A planet naturally wants to travel in a straight line. If the sun disappeared right now, the Earth would start travelling in a straight line and fly away into space (freezing in the meantime). If the Earth had NO SPEED and the sun was back, the Earth would simply fall into the Sun.
However, the Earth does have speed, and this speed allows it FALL at the same rate as the curvature of the Sun. And so it never actually gets much closer to the sun. This is simply what an orbit is.
Of course, an orbit requires the CORRECT SPEED. If you go too slow, you clearly fall or spiral into the sun. And, believe it or not, if you go too fast, the sun's gravity doesn't curve you enough from your straight line path, and you spiral outwards away from the solar system.
Only with the CORRECT SPEED will a planet stay in orbit.
Each planet has its own personal correct speed that corresponds to its distance from the Sun. Mercury, being closest to the Sun, needs to travel the fastest in order to avoid falling into the Sun. Neptune, on the other hand, needs to go relatively slowly in order not to fly off into space. In general, the closer you are to the sun, the faster you have to go to remain in orbit.
If you drop a ball, it has no initial horizontal speed, and gravity clearly pulls it to the center of the Earth. No orbit there!
Now consider shooting a cannonball horizontally off a cliff. The cannonball will make some progress is moving sideways before gravity pulls it to the ground. However, if we could shoot the cannonball with enough speed, it would 'FALL' at the same rate as the Earth curves, and so never actually get closer to the ground. Thus, it would keep "falling" forever and it went around and around. This is essentially what an orbit is.
A planet naturally wants to travel in a straight line. If the sun disappeared right now, the Earth would start travelling in a straight line and fly away into space (freezing in the meantime). If the Earth had NO SPEED and the sun was back, the Earth would simply fall into the Sun.
However, the Earth does have speed, and this speed allows it FALL at the same rate as the curvature of the Sun. And so it never actually gets much closer to the sun. This is simply what an orbit is.
Of course, an orbit requires the CORRECT SPEED. If you go too slow, you clearly fall or spiral into the sun. And, believe it or not, if you go too fast, the sun's gravity doesn't curve you enough from your straight line path, and you spiral outwards away from the solar system.
Only with the CORRECT SPEED will a planet stay in orbit.
Each planet has its own personal correct speed that corresponds to its distance from the Sun. Mercury, being closest to the Sun, needs to travel the fastest in order to avoid falling into the Sun. Neptune, on the other hand, needs to go relatively slowly in order not to fly off into space. In general, the closer you are to the sun, the faster you have to go to remain in orbit.
Below is an interactive program that allows you to look at the orbits in different systems. You can control the MASS of each object (sun, planet, moon), the INITIAL SPEED and INITIAL DIRECTION of each planet, and the INITIAL distance. Note, if you reduce the speed arrow too much, the planet crashes into the Sun... if you make the speed arrow too fast, the planet flies away. You can also select the Preset Systems and see what they do.
That concludes the notes on The Solar System.
ACTIVITIES FOR THIS CHAPTER
s 1. PIN THE PLANET ON THE SOLAR SYSTEM
The teacher will draw a 1cm drawing of Sun on the white board. Guess where you think Mercury, Venus, and Earth are. Place your initials next to your guesses.
2. ACTIVITY 1: Scale Distance of Solar System
Make an actual scaled version of the solar system (size of sun and distances to planets are to scale, the planet sizes would need to be microscopic with even Jupiter only having a diameter of 1mm). For instructions, click here.
3. WORKSHEETS 101 to 107
Complete all the worksheets. Although you have a hard black-and-white copy, you can get a coloured PDF version by clicking here.
4. Explore orbits with PhET My Solar System
Just above is an embedded version of the PhET 'My Solar System' interactive animation. Explore how MASS, DISTANCE and SPEED affect the ability of an object to ORBIT around a larger orbit.
5. Optional: NASA's Eyes on the Solar System
Go to http://eyes.nasa.gov/ and scroll down to Eyes of the Solar System. Step 1 is to download the APP which gives you the software to use any of NASA's Eye programs. When done, you can then go and LAUNCH SIMPLE from the same page and this will start the program. From here you can explore the solar system in a virtual space craft.
6. Optional: Voyage to the Planets TV Show
Watch the 'mockumentary' Voyage to the Planets that acts like a documentary that follows a space mission with PEOPLE to explore all the planets out to Saturn. In goes for a while but is quite interesting as the producers of the show tried to be as accurate as possible.
The teacher will draw a 1cm drawing of Sun on the white board. Guess where you think Mercury, Venus, and Earth are. Place your initials next to your guesses.
2. ACTIVITY 1: Scale Distance of Solar System
Make an actual scaled version of the solar system (size of sun and distances to planets are to scale, the planet sizes would need to be microscopic with even Jupiter only having a diameter of 1mm). For instructions, click here.
3. WORKSHEETS 101 to 107
Complete all the worksheets. Although you have a hard black-and-white copy, you can get a coloured PDF version by clicking here.
4. Explore orbits with PhET My Solar System
Just above is an embedded version of the PhET 'My Solar System' interactive animation. Explore how MASS, DISTANCE and SPEED affect the ability of an object to ORBIT around a larger orbit.
5. Optional: NASA's Eyes on the Solar System
Go to http://eyes.nasa.gov/ and scroll down to Eyes of the Solar System. Step 1 is to download the APP which gives you the software to use any of NASA's Eye programs. When done, you can then go and LAUNCH SIMPLE from the same page and this will start the program. From here you can explore the solar system in a virtual space craft.
6. Optional: Voyage to the Planets TV Show
Watch the 'mockumentary' Voyage to the Planets that acts like a documentary that follows a space mission with PEOPLE to explore all the planets out to Saturn. In goes for a while but is quite interesting as the producers of the show tried to be as accurate as possible.
2015 Students: Ignore anything below this sentence!!!
Periods of the planets of the inner solar system (Starry Night Computer Software)
Use Starry Night to move yourself in an alien ship to a point hovering above the solar system. Watch down on the clockwork of the inner solar system and work out the periods of the planets for yourself, as well as the periods of some minor planets in the Asteroid Belt.
The PDF for this activity is here: http://www.avilafm.com/easyperiods.pdf
You will need: Starry Night on your Computer
1D Scale Model of the Distances to the Planets (Hands On - Strongly Encouraged to do)
Get a measuring tape that goes for at least 30m, or if not, for at least 15m.
Go outside to the area between the Year 11 and Year 10 Buildings. Near the front office, hold your measuring tape and stretch it out towards Charles street. If you have 30m or more, let 1m = 1 AU. If you only had 15m, you will need to make 50cm = 1AU.Place a strip of masking tape at 0cm and write on the tape SUN. This represents the position of the sun.
Next, place a strip of masking tape at the 1m mark and write on the tape EARTH (use 50cm if you don't have 30m of tape measure). This represent the position of Earth. Now, using more strips of masking tape, and the scale made by the SUN and EARTH, put strips of masking tape at the correct places for all the other planets (use average distance). The whole thing is just in a 1D line, even though the planets are never all lined up in a line at the one time. We know the planets would be somewhere on a circle at that distance, but we don't have the space, so we just line each planet up along the measuring tape. When you have done, get a phone or computer and film yourself walking along the line, revealing the position of the planets as you move from the 0cm mark to the 30cm mark. Done!
You will need: Tape Measure, masking tape, phone or laptop.
Long Activities:
2D Scale Model of the Size of the Planets (Hands On)
Create a scale model of each of the planets. Each planet will be a circle representing a side on view of the planet. Use the diameters of each planet to keep them to scale. Try making (i) a set with the Sun and all the planets, (ii) a set with Jupiter as the largest and all the planets, (iii) a set with Earth as the largest and just the smaller planets (and moons if you wish). You may choose to stick each of the circles of ONE of your sets onto some poster paper.
You will need: Large Coloured Paper, Circle Drawing Compass (alternatively, string + pin + pencil), Ruler.
TV Show: Voyage to the Solar System (Show)
This serious mockumentary pretends humans are really sending a mission with people to all the planets and follows both the astronauts and the people back in mission control as the mission takes place. Quite interesting. 2 hours (1 hour for each part).
Part 1: https://youtu.be/9rQIKhWlGH8
Part 2: https://youtu.be/1HubiaJYnLE
Brochure to the Planets
Imagine it is January 1st 2020 and we have just found a way to cheaply go and see all the planets. Spaceships can now travel at 1 AU per month. You are working for a travel agent company that offers clients the chance to go on a Round the Solar System Tour to begin on January 1st 2021.
You need to decide what destinations will be on this tour (what's most interesting... volcanoes on Mars, icy moons, volcanic moons, etc.), the order in which you will see things, and (Using Earth to Mars = 1 month) work out how long its going to take to go from place to place (NOTE: At these speeds, assume moons of planets are only 1 day away). You should do the top activity in this list from Starry Night and use the software, considering DATES and DISTANCES to work out how long its going to take to get to each destination.
The brochure should include all the highlights (pictures/descriptions) and an itinary of places and dates and a rough 'map' of where you are going. Can be a traditionary fold-in-3 brochure or it could be an online/computer brochure.
You will need: Starry Night. Research cool places in the solar system. Internet for images. Pages/Key Note/Weebly or something to make it on.
Volume and Density of the Planets (MATHS)
Using the data about the diameter and mass of the planets, you can work out the volume and density of each planet. What planet is the most dense might surprise you! If fact, the whole order might surprise you. Just use a formula to calculate it or watch a video to understand where the formula comes from.
PDF instructions are found here: http://www.avilafm.com/easyvolume.pdf
You will need: Your brain.
Speed of the Planets (MATHS)
Find the speed of each planet as it moves around the sun on its orbit. There is also an insanely difficult CHALLENGE you might want to take up to explore the relationship between distance from sun and the velocity of a planet.
Instructions at: http://www.avilafm.com/planetspeeds.pdf
You will need: Your brain
Periods of the planets of the inner solar system (Starry Night Computer Software)
Use Starry Night to move yourself in an alien ship to a point hovering above the solar system. Watch down on the clockwork of the inner solar system and work out the periods of the planets for yourself, as well as the periods of some minor planets in the Asteroid Belt.
The PDF for this activity is here: http://www.avilafm.com/easyperiods.pdf
You will need: Starry Night on your Computer
1D Scale Model of the Distances to the Planets (Hands On - Strongly Encouraged to do)
Get a measuring tape that goes for at least 30m, or if not, for at least 15m.
Go outside to the area between the Year 11 and Year 10 Buildings. Near the front office, hold your measuring tape and stretch it out towards Charles street. If you have 30m or more, let 1m = 1 AU. If you only had 15m, you will need to make 50cm = 1AU.Place a strip of masking tape at 0cm and write on the tape SUN. This represents the position of the sun.
Next, place a strip of masking tape at the 1m mark and write on the tape EARTH (use 50cm if you don't have 30m of tape measure). This represent the position of Earth. Now, using more strips of masking tape, and the scale made by the SUN and EARTH, put strips of masking tape at the correct places for all the other planets (use average distance). The whole thing is just in a 1D line, even though the planets are never all lined up in a line at the one time. We know the planets would be somewhere on a circle at that distance, but we don't have the space, so we just line each planet up along the measuring tape. When you have done, get a phone or computer and film yourself walking along the line, revealing the position of the planets as you move from the 0cm mark to the 30cm mark. Done!
You will need: Tape Measure, masking tape, phone or laptop.
Long Activities:
2D Scale Model of the Size of the Planets (Hands On)
Create a scale model of each of the planets. Each planet will be a circle representing a side on view of the planet. Use the diameters of each planet to keep them to scale. Try making (i) a set with the Sun and all the planets, (ii) a set with Jupiter as the largest and all the planets, (iii) a set with Earth as the largest and just the smaller planets (and moons if you wish). You may choose to stick each of the circles of ONE of your sets onto some poster paper.
You will need: Large Coloured Paper, Circle Drawing Compass (alternatively, string + pin + pencil), Ruler.
TV Show: Voyage to the Solar System (Show)
This serious mockumentary pretends humans are really sending a mission with people to all the planets and follows both the astronauts and the people back in mission control as the mission takes place. Quite interesting. 2 hours (1 hour for each part).
Part 1: https://youtu.be/9rQIKhWlGH8
Part 2: https://youtu.be/1HubiaJYnLE
Brochure to the Planets
Imagine it is January 1st 2020 and we have just found a way to cheaply go and see all the planets. Spaceships can now travel at 1 AU per month. You are working for a travel agent company that offers clients the chance to go on a Round the Solar System Tour to begin on January 1st 2021.
You need to decide what destinations will be on this tour (what's most interesting... volcanoes on Mars, icy moons, volcanic moons, etc.), the order in which you will see things, and (Using Earth to Mars = 1 month) work out how long its going to take to go from place to place (NOTE: At these speeds, assume moons of planets are only 1 day away). You should do the top activity in this list from Starry Night and use the software, considering DATES and DISTANCES to work out how long its going to take to get to each destination.
The brochure should include all the highlights (pictures/descriptions) and an itinary of places and dates and a rough 'map' of where you are going. Can be a traditionary fold-in-3 brochure or it could be an online/computer brochure.
You will need: Starry Night. Research cool places in the solar system. Internet for images. Pages/Key Note/Weebly or something to make it on.
Volume and Density of the Planets (MATHS)
Using the data about the diameter and mass of the planets, you can work out the volume and density of each planet. What planet is the most dense might surprise you! If fact, the whole order might surprise you. Just use a formula to calculate it or watch a video to understand where the formula comes from.
PDF instructions are found here: http://www.avilafm.com/easyvolume.pdf
You will need: Your brain.
Speed of the Planets (MATHS)
Find the speed of each planet as it moves around the sun on its orbit. There is also an insanely difficult CHALLENGE you might want to take up to explore the relationship between distance from sun and the velocity of a planet.
Instructions at: http://www.avilafm.com/planetspeeds.pdf
You will need: Your brain