Properties of the Planets Terrestrial Planets Mercury Venus

Properties of the Planets • Terrestrial Planets – Mercury – Venus – Earth – Mars • Jovian Planets This presentation will show you some of the important physical differences between the Terrestrial and Jovian Planets. First the Terrestrial planets…

Mercury: Heavily cratered ancient rocky surface. The innermost of the planets. We have only photographed half of its surface because the planet rotates very slowly and the flyby spacecraft (Mariner) could only photograph the sunlit portion. Mercury

Venus: Covered from pole to pole with bright clouds. The surface cannot be seen from orbit at visual wavelengths. Radar instruments on the Magellan spacecraft mapped the surface and found very few craters suggesting an active geology that erases resurfaces the ancient landscapes Venus

Earth: The only planet with liquid water on its surface and the only planet with molecular oxygen in its atmosphere. The Earth’s surface, like that of Venus, has very few impact craters, due to an active geology (plate tectonics) and robust weathering from wind and rain. Earth

Mars: The last Terrestrial planet. If has an anomolusly low density for a terrestrial planet, suggesting that it is made of a different mix of materials than the other terrestrial planets. Its surface shows signs of ancient geology, but no evidence recent wide scale activity. Where is the water on Mars is the focus of current scientific work. Mars

Properties of the Planets • Terrestrial Planets – Mercury – Venus – Earth – Mars Now, the Jovian planets. . . • Jovian Planets – Jupiter – Saturn – Uranus – Neptune

Jupiter: The closest Jovian planet. Composed almost entirely of hydrogen and helium gas, this planet began as a giant ball of ice and rock that attracted a deep atmosphere of gas from the nebula (cloud of gasses) the Sun and planets formed from. Jupiter

Saturn: Almost ten times farther from the Sun than the Earth, this could world of gasses the most spectacular set of rings of all the Jovian planets. The rings are believed to be the remains of a moon that drifted to close to Saturn abd broke apart, distributing its material around the equatorial plane. Saturn

Unanus: The first telescopically discovered (1781) planet. It remains the most mysterious of planets. No clouds can be seen it is hydrogen and helium atmosphere tinted blue by a slight enrichment of methane. Further adding to the mystery, the rotation axis of Uranus is tipped almost 90 degrees relative to the ecliptic suggesting some catastrophic event slammed into Uranus and “knocked” it over. Uranus

Neptune: Much like Uranus in appearance, size and compostion, although cluds can be seen throuogh the atmosphere. These most distant Jovian planets are the runts of the Jovian litter, yet they still occupy a volume more than that of 64 Earth’s. Neptune

Properties of the Planets • Terrestrial Planets – Mercury – Venus – Earth – Mars • Jovian Planets – Jupiter – Saturn – Uranus – Neptune What about Pluto? We’ll cover Pluto a bit later…. .

Pluto: As we shall see shortly, Pluto is a world that doesn’t fit the pattern established by the other planets. It is far too small and of the wrong composition to be a Jovian planet and too small, too far away and the wrong composition to be a Terrestrial planet. Pluto, shown here with its moon Charon, may be pieces of a planet that was not able to finish its formation. It is considered to be a piece of debris leftover from the era of planet formation. Pluto

Planet Distance from Sun, AU Mass MEarth Radius REarth Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto Let’s look at the numbers. Please try to see the similarities within each class of planet and the contrasts between them. Density gm/cm 3

Planet Distance from Sun, AU Mercury 0. 39 Venus 0. 72 Earth 1. 0 Mars 1. 5 Jupiter 5. 2 Saturn 9. 5 Uranus 19 Neptune 30 Pluto 39 Mass MEarth Radius REarth Density gm/cm 3

Planet Distance from Sun, AU Mercury 0. 39 Venus 0. 72 Earth 1. 0 Mars 1. 5 Jupiter 5. 2 Saturn 9. 5 Uranus 19 Neptune 30 Pluto 39 Mass MEarth Radius REarth Terrestrial Planets Density gm/cm 3

Planet Distance from Sun, AU Mercury 0. 39 Venus 0. 72 Earth 1. 0 Mars 1. 5 Jupiter 5. 2 Saturn 9. 5 Uranus 19 Neptune 30 Pluto 39 Mass MEarth Radius REarth Terrestrial Planets Jovian Planets Density gm/cm 3

This meter stick ninja is a cute way of visualizing the relative distances of the planets form the Sun. In this

Meter-stick Ninja Earth 1” Jupiter 5. 2” Uranus 19” Pluto 39” Saturn 10” Mercury 1/3” Venus ¾” Mars 1 ½” Neptune 30” Notice that, at this scale, all the Terrestrial Planets are within 1½ inches from the Sun. The Jovian planets are spread between 5 inches and 30 inches.

Sunrise on the Planets A simulation The next series of slides are meant to help you visualize the effect of the vast distances of the Solar System by simulating, in a simple way, what sunrise would look like from each planet, taking into account its distance from the Sun. At the bottom of each slide appears the amount of solar energy available at that distance from the Sun. The solar energy follows an inverse square law like gravity. Notice how rapidly the available solar energy drops as you progress through the solar system.

Sunrise on Mercury Available Solar Energy ~9, 350 W/m 2

Sunrise on Earth Available Solar Energy ~1, 350 W/m 2

Sunrise on Jupiter Available Solar Energy ~50 W/m 2

Sunrise on Saturn Available Solar Energy ~15 W/m 2

Sunrise on Uranus Available Solar Energy ~4 W/m 2

Sunrise on Neptune . Available Solar Energy ~1. 6 W/m 2

Planet Distance from Sun, AU Mass MEarth Mercury 0. 39 0. 06 Venus 0. 72 0. 82 Earth 1. 0 Mars 1. 5 0. 11 Jupiter 5. 2 318 Saturn 9. 5 95 Uranus 19 14 Neptune 30 17 Pluto 39 0. 002 Radius REarth Density gm/cm 3 Now we’ll compare the masses of the planets. Note that we will use the Earth as a standard mass for convenience.

Planet Distance from Sun, AU Mass MEarth Mercury 0. 39 0. 06 Venus 0. 72 0. 82 Earth 1. 0 Mars 1. 5 0. 11 Jupiter 5. 2 318 Saturn 9. 5 95 Uranus 19 14 Neptune 30 17 Pluto 39 0. 002 Radius REarth Density gm/cm 3 Terrestrial Planets

Planet Distance from Sun, AU Mass MEarth Mercury 0. 39 0. 06 Venus 0. 72 0. 82 Earth 1. 0 Mars 1. 5 0. 11 Jupiter 5. 2 318 Saturn 9. 5 95 Uranus 19 14 Neptune 30 17 Pluto 39 0. 002 Radius REarth Density gm/cm 3 Terrestrial Planets Jovian Planets

Imagine a “planetary balance” that could weight the planets in terms of Earth masses. How would the other planets compare?

About 9 planet Mars’ to equal one Earth

About 17 planet Earth’s to equal one Neptune

About 318 planet Earth’s to equal one Jupiter

Planet Distance from Sun, AU Mass MEarth Radius REarth Mercury 0. 39 0. 06 0. 38 Venus 0. 72 0. 82 0. 95 Earth 1. 00 Mars 1. 5 0. 11 0. 53 Jupiter 5. 2 318 11. 2 Saturn 9. 5 95 9. 5 Uranus 19 14 4. 0 Neptune 30 17 3. 9 Pluto 39 0. 002 0. 18 Density gm/cm 3 Now, we’ll examine the radii of the planets.

Planet Distance from Sun, AU Mass MEarth Radius REarth Mercury 0. 39 0. 06 0. 38 Venus 0. 72 0. 82 0. 95 Earth 1. 00 Mars 1. 5 0. 11 0. 53 Jupiter 5. 2 318 11. 2 Saturn 9. 5 95 9. 5 Uranus 19 14 4. 0 Neptune 30 17 3. 9 Pluto 39 0. 002 0. 18 Density gm/cm 3 Terrestrial Planets

Terrestrial Planet Radii Earth Venus These images of the Terrestrial planets are approximately to scale. Mars Mercury

Planet Distance from Sun, AU Mass MEarth Radius REarth Mercury 0. 39 0. 06 0. 38 Venus 0. 72 0. 82 0. 95 Earth 1. 00 Mars 1. 5 0. 11 0. 53 Jupiter 5. 2 318 11. 2 Saturn 9. 5 95 9. 5 Uranus 19 14 4. 0 Neptune 30 17 3. 9 Pluto 39 0. 002 0. 18 Density gm/cm 3 Terrestrial Planets Jovian Planets

Jovian Planets radii These images of the Jovian planets are approximately to scale. Uranus Neptune Jupiter Saturn

Notice how large all the Jovian planets are compared to the largest Terrestrial Planet, Earth Jovian Planets compared to Earth Jupiter Saturn Uranus Neptune

A Mnemonic for the Radii of Terrestrial Planets …and Friends This is a useful memory aid for the radii of Terrestrial Planets.

Planet Mercury Venus Earth Mars Mass Radius Distance from Sun, MEarth density. REarth Now, AU We’ll examine Density a 0. 39 of an object 0. 06 tells 0. 38 scientist something about the 0. 72 0. 82 0. 95 composition of the object. 1. 0 bench mark 1. 0 densities 1. 00 Some follow: 1. 5 0. 11 0. 53 Density gm/cm 3 5. 4 5. 2 5. 5 3. 9 Jupiter 5. 2 Material 318 Density 11. 2 1. 3 Saturn 9. 5 Water 951. 0 g/cm 9. 53 0. 7 Uranus 19 14 4. 0 1. 3 30 17 3. 9 1. 6 39 0. 002 0. 18 2. 0 Neptune Pluto Rock Iron 3 to 5 g/cm 3 7. 8 g/cm 3

Planet Mercury Venus Mass Radius Distance from Sun, Most. AU Terrestrial. M Planets have REarth densities around 5. 3 g/cm 3 0. 39 a composition 0. 06 of mostly 0. 38 indicating rock with a smaller amount of iron Density gm/cm 3 5. 4 0. 72 0. 82 0. 95 5. 2 Earth 1. 00 5. 5 Mars 1. 5 0. 11 0. 53 3. 9 Jupiter 5. 2 318 11. 2 1. 3 Saturn 9. 5 95 9. 5 0. 7 Uranus 19 14 4. 0 1. 3 Neptune 30 17 3. 9 1. 6 Pluto 39 0. 002 0. 18 2. 0

Planet Mercury Venus Mass Radius Distance from Sun, Most. AU Terrestrial. M Planets have REarth densities around 5. 3 g/cm 3 0. 39 a composition 0. 06 of mostly 0. 38 indicating rock with a smaller amount of iron Density gm/cm 3 5. 4 0. 72 0. 82 0. 95 5. 2 Earth 1. 00 5. 5 Mars 1. 5 0. 11 0. 53 3. 9 Jupiter 5. 2 318 11. 2 1. 3 Mars, a anomalously 9. 5 however, has 95 9. 5 low density. We’ll try to explain 19 the density is 14 4. 0 why low when we discuss planet formation. 0. 7 Saturn Uranus Neptune Pluto 1. 3 30 17 3. 9 1. 6 39 0. 002 0. 18 2. 0

Planet Distance from Sun, AU Mass MEarth Radius REarth Density gm/cm 3 Mercury 0. 39 0. 06 0. 38 5. 4 Venus 0. 72 0. 82 0. 95 5. 2 Earth 1. 00 5. 5 Mars 1. 5 0. 11 0. 53 3. 9 Jupiter 5. 2 318 11. 2 1. 3 Saturn Uranus Neptune Pluto The Jovian planet densities are MUCH 9. 5 lower than the 95 Terrestrial 9. 5 planets. These densities are 19 14 4. 0 consistent with a compositon of compressed gas. 0. 7 1. 3 30 17 3. 9 1. 6 39 0. 002 0. 18 2. 0

This graph displays the density vs. distance from the Sun for each planet

This trend can be model by the dotted line.

Planet Distance from Sun, AU Mass MEarth Radius REarth Density gm/cm 3 Mercury 0. 39 0. 06 0. 38 5. 4 Venus 0. 72 0. 82 0. 95 5. 2 Earth Mars Jupiter 1. 0 contrasts Pluto’s 1. 0 properties 1. 00 with the 5. 5 This slide other 1. 5 planets. You can it does not fit the 0. 11 see that 0. 53 3. 9 pattern of the Jovian planet in mass, radius or 5. 2 Neither does 318 11. 2 1. 3 density. it fit the Terrestrial planets. Saturn 9. 5 95 9. 5 0. 7 Uranus 19 14 4. 0 1. 3 Neptune 30 17 3. 9 1. 6 Pluto 39 0. 002 0. 18 2. 0

Planet Distance from Sun, AU Mass MEarth Radius REarth Density gm/cm 3 Mercury 0. 39 0. 06 0. 38 5. 4 Venus 0. 72 0. 82 0. 95 5. 2 Earth 1. 00 5. 5 Mars 1. 5 0. 11 0. 53 3. 9 Jupiter 5. 2 318 11. 2 1. 3 Saturn 9. 5 95 9. 5 0. 7 Uranus 19 14 4. 0 1. 3 Neptune 30 17 3. 9 1. 6 In my on-site class I ask my students to memorize the numbers you can 39 no less of 0. 002 0. 18 2. 0 see. Pluto on this slide. I expect you.

Planet Distance from Sun, AU Mass MEarth Radius REarth Mercury. Please notice 0. 39 that the closest 0. 06 Jovian planet, 0. 38 Density gm/cm 3 5. 4 Jupiter, is also the largest in mass and radius. We Venus will have 0. 72 an explanation 0. 82 for why the 0. 95 closest Jovian 5. 2 planet is the largest and why the succeeding Jovian Earth planets tend 1. 0 to get smaller 1. 00 5. 5 in mass and radius Solar System. 3. 9 Mars when we look 1. 5 at the formation 0. 11 of the 0. 53 Jupiter 5. 2 318 11. 2 1. 3 Saturn 9. 5 95 9. 5 0. 7 Uranus 19 14 4. 0 1. 3 Neptune 30 17 3. 9 1. 6 Pluto 39 0. 002 0. 18 2. 0

Planetary Systems are characterized by two classes of planets with mutually exclusive properties.

Planetary Systems are characterized by two classes of planets with mutually exclusive properties. • Terrestrial Planets – Close to the central star – Small in mass and radius – High density

Planetary Systems are characterized by two classes of planets with mutually exclusive properties. • Terrestrial Planets – Close to the central star – Small in mass and radius – High density • Jovian Planets – Far from the central star – Large in mass and radius – Low density

Planetary Systems are characterized by two classes of planets with mutually exclusive properties. • Terrestrial Planets – Close to the central star – Small in mass and radius – High density • Jovian Planets – Far from the central star – Large in mass and radius – Low density Why are planetary systems organized in this manner? Is there an over-arching principle that explains this pattern? How common are planetary systems around other stars and how common are Earth-like planets?

Planetary Systems are characterized by two classes of planets with mutually exclusive properties. • Terrestrial Planets – Close to the central star – Small in mass and radius – High density • Jovian Planets – Far from the central star – Large in mass and radius – Low density Why are planetary systems organized in this manner? Is there an over-arching principle that explains this pattern? How common are planetary systems around other stars and how common are Earth-like planets?

Planetary Systems are characterized by two classes of planets with mutually exclusive properties. • Terrestrial Planets – Close to the central star – Small in mass and radius – High density • Jovian Planets – Far from the central star – Large in mass and radius – Low density Why are planetary systems organized in this manner? Is there an over-arching principle that explains this pattern? How common are planetary systems around other stars and how common are Earth-like planets?

We will answer these questions later. Planetary Systems are characterized by two classes of planets with mutually exclusive properties. • Terrestrial Planets – Close to the central star – Small in mass and radius – High density • Jovian Planets – Far from the central star – Large in mass and radius – Low density Why are planetary systems organized in this manner? Is there an over-arching principle that explains this pattern? How common are planetary systems around other stars and how common are Earth-like planets?