Our Solar System & Scale Grade 6 Image Credit: Slyavula Education

Content Topics Scale of our Solar System in relation to our Milky Way Galaxy and the Observable Universe Objects contained in our Solar System Planet data and scale comparisons Developing a scale

Our Solar System Source: Solar System Videos

Our Milky Way Galaxy Video by ESA https://www.youtube.com/watch?v=eVEMOjT2BgY Video by ESA

Our Location in the Universe

Our Place in the Solar System We live on planet Earth 3rd Planet Diameter = 7,917 miles (0.043 light seconds) One planet in the Solar System Diameter = 3.74 light years

Our Location in Space In the Milky Way Galaxy Part of the Local Group 1012 stars Diameter = 100,000 light years Part of the Local Group Cluster of galaxies Diameter = 10,000,000 light years

Our spot in the Visible Universe Within the Virgo Supercluster Cluster of galaxy clusters Diameter = 110,000,000 light years One tiny spot in our visible Universe What we can currently see “Diameter” = 14 Billion LY

Visible Universe Image Credit: An Atlas of the Universe

Within one Universe Expanded Universe Diameter 93 Billion LY https://www.youtube.com/watch?v=F353xaKnQ2I

Practice Model the scale of our solar system in a sketch of the visible universe. Our solar system would be a tiny dot on this page that would not be visible to the naked eye. Compare the size (diameter) of our Solar System (3.74 LY) to the size (diameter) of our Milky Way Galaxy (100,000 LY). 100,000 = 26,738 The Milky Way Galaxy is 26,738 times 3.74 1 bigger in diameter!

(only one side of the solar system is shown) More Practice If the Solar system is 3.74 light years across, what is the distance shown in the image below? How do you know? ½(3.74) = 1.87 LY (only one side of the solar system is shown) Image Credit: astromonytrek.com

What is contained within our solar system? Our solar system is centered on the Sun. Planets orbit the Sun. Moons orbit the planets. Dwarf planets orbit the Sun. Asteroids and Comets orbit the Sun.

Practice What do you think the numbers are? How many of each object are contained in our solar system? How do the sizes of these objects compare? Rank order them. 1st Stars (1 star) 2nd Planets (8 planets) 3rd Moons (100’s) 4th Asteroids (10,000’s) 5th Comets (Millions or Billions)

Our Sun Image Credit: NASA

Sun Scale Diameter = 1,391,400 km (864,761 miles) 109 Earths would fit across the diameter of the Sun 1,300,000 Earths would fit inside of the Sun

Our 8 Planets & Pluto Image Credit: NASA

Terrestrial Planets Which planets are comparable in size? Earth and Venus What fraction of Mar’s diameter is covered by the Valles Marineris? about 2/3rds Image Credit: Space.com

Terrestrial Planet Layers Which planets have similar size layers? Venus and Earth have similar thickness mantles. Image Credit: Wikimedia commons

Practice The Earth has a radius of 6,378 kilometers (3,963 miles). Earth’s mantle is 2,900 kilometers thick. What fraction of the Earth is mantle? 2,900 = 1.0 The mantle is approximately half the 6,378 2.2 thickness of Earth

Jovian Planets Based on the image, how much larger are Jupiter and Saturn as compared to Uranus and Neptune? Jupiter & Saturn are about 6 times larger than Uranus & Neptune Image Credit: NASA

Jupiter’s Spot Jupiter’s Great Red Spot is the longest lived weather disturbance in the solar system. How many Earth’s would fit into Jupiter’s red spot? 3-4 Earths Video & Image by NASA

Sizes of Planets Planet Name Planet Diameter Mercury 4,878 3,031 Venus (kilometers) (Miles) Mercury 4,878 3,031 Venus 12,104 7,521 Earth 12,756 7,927 Mars 6,792 4,221 Jupiter 142,974 88,589 Saturn 120,536 74,914 Uranus 51,118 31,770 Neptune 49,528 30,782

Practice Name two different ways to compare sizes of planets in our solar system. Radius of planet Diameter of planet Orbital radius Thickness of comparable layers

Moons One of Saturn’s Moons Moon Phobos Titan Image Credit: NASA

Earth and Jupiter Earth has one Moon. Jupiter has 68 moons, the largest is Ganymede. How could we use data to compare scale sizes? Compare in a ratio (set-up a fraction) Subtraction Scale sketch Earth Radius Moon Jupiter Ganymede 6,371 km 1,738 71,492 km 2,631 km

Hubble Space Telescope Dwarf Planets Pluto is a Dwarf Planet Dwarf planets are defined as objects that are similar to planets but do not meet all planet criteria. Hubble Space Telescope NASA

Dwarf Planet Pluto New Horizons Image, NASA

Asteroids Smaller than planets Rocky Image Credit: NASA

Comets Smaller than planets Icey Comet Halley's Nucleus APOD 2010 January 4

Image Credit: NASA

Where are objects located in our Solar System? The General Order is: Sun, Mercury, Venus, Earth, Mars, Main Asteroid Belt (asteroids), Jupiter, Saturn, Uranus, Neptune, Pluto, Kuiper Belt (Plutinos and comets), and the Oort Cloud (comets)

Orbital Radius Planet Orbital Radius The planets in our solar system orbit in ellipses that are nearly a circle. How do the scales of planet separation compare for Terrestrial planets versus Jovian planets? How did you determine this? Planet Orbital Radius Mercury 58 Million km Venus 108 Million km Earth 150 Million km Mars 228 Million km Jupiter 779 Million km Saturn 1434 Million km Uranus 2873 Million km Neptune 4495 Million km

Other Stars have Orbiting Planets too! HR 8799 harbors four super-Jupiters orbiting with periods that range from decades to centuries. Motion interpolate was used on 7 images of HR 8799 taken from the Keck Telescope over 7 years to create this image. Movie Credit: Jason Wang and Christian Marois

Practice The planet’s in HR 8799 are called super Jupiters. What do you think that means? Based on the scale properties of our solar system, what is a super Jupiter? A Super Jupiter is a planet that is 2 or more times bigger in size than Jupiter. Which planets in HR 8799 would have the longer orbital periods? How do you know? The planets orbiting farthest from the star Can observe them taking longer to orbit We know it takes longer for planets in our solar system to orbit if they are far from the Sun

How is a scale determined? Scale is based on factors or fractions. 10 times bigger than the actual size 1/4th the actual size A scale model can be numbers, a drawing, or something you build.

One water molecule or Our Solar System Scale Scale models are used to see object properties that are very small or very big. One water molecule or Our Solar System 0.275 nanometers 150 Million km Image Credit: wordpress.com & NASA

Practice If you wanted to fit a scale model of the solar system into your classroom, or outside on the playground, what scale would you use? How would you make it fit? Average Sun-Mercury distance is 58 million km Average Sun-Neptune distance is 4,495 million km Average Sun-Oort Cloud distance is 750,038 million km An easy first step would be to drop the million. Another step could be to divide each by 58. Then each scaled km could be equal to 1 step. 58 million km = 1 step 4495 million km = 77.5 steps 740,038 million km = 12,932 steps