3.4/3.5 terrestrial & gas giant planets ms. grant

3.4/3.5Terrestrial &

Gas GiantPlanets

Ms. Grant

Remember the lesson goals!

1. What is known about the terrestrial planets?

2. What is known about the gas giant planets?

3.4 TERRESTRIAL PLANETS

Extreme to the Core

What are the terrestrial planets?

• The terrestrial planets are the four small, dense, rocky planets that orbit closest to the sun.

In order by distance from the sun, these planets are Mercury, Venus, Earth, and Mars.

The terrestrial planets have similar compositions and consist of an outer crust, a central core, and a mantle that lies between the crust and core.

Unit 3 Lesson 4 The Terrestrial Planets

On Mars there is a greater range of temperatures as compared to Earth. This is because of the thin atmosphere on Mars.

• One astronomical unit is the average distance between the sun and Earth, or approximately 150 million km.

Earth and Venus have diameters that are nearly equal in size.

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• Earth has prograde rotation, which means that it rotates counterclockwise about its axis as seen from above its north pole.

• Venus has retrograde rotation, which means that it rotates clockwise about its axis as seen from above its north pole.



• It takes more time for Venus to rotate once about its axis than it takes for the planet to revolve once around the sun.

• The surface of Venus is covered with thousands of volcanoes.

• Venus’s surface also has craters.

On Venus a day is longer than a year! It also has the densest atmospheres of the terrestrial planets.




• Earth is the only planet that can support life.

• Earth has liquid water, an energy source, an atmosphere that contains oxygen, and a number of ecosystems for different organisms to inhabit.

Matter is continuously cycled between the environment and living things.


• Earth is the only terrestrial planet whose surface is divided into tectonic plates.

• Movement of these plates causes the continents to change positions over long periods of time.

• Tectonic plate motion, together with weathering and erosion, has erased most surface features older than 500 million years.



The moon rotates about its axis in the same time it orbits Earth. Therefore, it keeps the same side facing Earth.

• The lunar day is a little more than 27 Earth days.

• The moon’s surface temperature can reach 127 °C in the daytime, and it can fall to –173 °C at night.



3.5 GAS GIANTS

A Giant Among Giants!


What is a gas giant planet?

Jupiter, Saturn, Uranus, and Neptune are the gas giant planets.

Gas giants have deep, massive gas atmospheres, which are made up mostly of hydrogen and helium. They have no surface to stand on.

The gas giant planets are large and cold.

Unit 3 Lesson 5 The Gas Giant Planets

Jupiter is the largest planet in the solar system.

• Jupiter’s mass is twice that of the other seven planets combined. It has the highest surface gravity in the solar system.



The center of Jupiter is extremely hot.

• Although all of the gas giant planets rotate rapidly, Jupiter rotates fastest of all. Its period of rotation is just under 10 hours.

Jupiter has a much greater atmospheric pressure than Earth does. Due to this reason spacecrafts have not been sent with Jupiter to explore.


• Saturn is the second-largest gas giant planet and is made mostly of hydrogen and helium.

• Saturn’s average density is less than that of water.


• Saturn’s most spectacular feature is a planetary ring system that circles the planet’s equator.

• A planetary ring system is a disk of material that circles a planet and consists of orbiting particles.

Saturn’s ring system has many individual rings that form complex bands. Between bands are gaps that may be occupied by moons.




• The atmosphere of Uranus is composed mostly of hydrogen and helium. It also contains methane.

• The methane absorbs red light, which gives the planet a blue-green color.


How is Uranus unique?

• For 21 years, the north pole faces the sun and the south pole is in darkness.

• After another 21 years, the poles are reversed. The south pole faces the sun and the north pole is in darkness for 21 years.



How is Uranus unique?

• Every place on Uranus has winter periods of constant darkness and summer periods of constant daylight.

• During spring and fall, Uranus has periods of both daytime and nighttime, just like on Earth.




Neptune is the most distant planet from the sun.

• Sunlight on Neptune is 900 times fainter than sunlight on Earth.

• High noon on Neptune may look like twilight on Earth.


• Neptune is almost the same size as Uranus.

• Like Uranus, Neptune has an atmosphere composed of hydrogen and helium, with some methane.

• Neptune’s bluish color is caused by the absorption of red light by methane.



Gas giants have more moons than Earth because they are more massive than Earth and thus have greater gravitational forces, so they could attract more objects.

Unit 3 Lesson 6 Small Bodies in the Solar System


Bigger Is not better


Where are small bodies in the solar system?• Scientists estimate that there are up to a trillion

small bodies in the solar system. They lack atmospheres and have weak surface gravity.

• The largest of the small bodies, the dwarf planets, are found in regions known as the asteroid belt and Kuiper belt.


Where are small bodies in the solar system? The Kuiper belt is located beyond the orbit of

Neptune. It contains Kuiper belt objects and comets.

• Comets are also located in the Oort cloud, which is a region that surrounds the solar system and extends almost halfway to the nearest star.

• Two other types of small bodies, asteroids and meteoroids, are located mostly between the orbits of Venus and Neptune.



What are dwarf planets?

• A dwarf planet is a celestial body that orbits the sun and is round because of its own gravity.

• A dwarf planet does not have the mass to have cleared other bodies out of its orbit around the sun.

• Five dwarf planets have been identified: Ceres, Pluto, Eris, Haumea, and Makemake.



What are Kuiper Belt objects?



A Kuiper belt object (KBO) is any of the minor bodies in the Kuiper belt. They are made of methane ice, ammonia ice, and water ice. Most Kuiper Belt objects have similar compositions to comets.

What do we know about comets?

• A comet is a small body of ice, rock, and dust that follows a highly elliptical orbit around the sun.

• All comets have a nucleus that is composed of ice and rock.

• If a comet approaches the sun, solar radiation and heating cause the comet’s ice to change to gas.




• A coma is a spherical cloud of gas and dust that comes off the nucleus.

• The ion tail of a comet is gas that has been ionized by the sun. This ion tail always points away from the sun.

• A second tail made of dust and gas curves backward along the comet’s orbit. This dust tail can be millions kilometers long.

If a comet is close to the sun, it could travel at a speed of 445 km/s.




The Oort cloud is a spherical region that surrounds the solar system.

• Comets can form in the Oort cloud when two objects collide, or when the gravity of a nearby star sends an object into the inner solar system.



On the Rocks


What do we know about asteroids?

An asteroid is a small, irregularly shaped, rocky object that orbits the sun.

Most asteroids are located in the asteroid belt between the orbits of Mars and Jupiter.

• The asteroid belt contains hundreds of thousands of asteroids, called main-belt asteroids.



The composition of asteroids varies. Hydrocarbons are materials that are found in asteroids.

• Some are rich in carbon.

• Others are rocky, with cores of iron and nickel.

• Some have a rocky core surrounded largely by ice.




• Some asteroids appear to be piles of rock loosely held together.

• Others contain economic minerals such as gold, iron, nickel, cobalt, and platinum.



Burned Out


What do we know about meteoroids, meteors, and meteorites? A sand grain- to boulder-sized rocky body that

travels through space is a meteoroid.

A bright streak of light that results when a meteoroid burns up in Earth’s atmosphere is called a meteor.

A meteorite is a meteoroid that reaches Earth’s surface without burning up.


What do we know about meteoroids, meteors, and meteorites? Meteoroids that burn up in the atmosphere that

are close enough to see are often referred to as shooting stars.

• Meteoroids come from the asteroid belt, Mars, the moon, and comets.

• Most meteoroids that enter Earth’s atmosphere do not reach Earth’s surface. Many explode in the upper atmosphere; others skip back into space.

• Large meteoroids that enter Earth’s lower atmosphere or strike Earth’s surface can be destructive.



3.4/3.5 terrestrial & gas giant planets ms. grant

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