THE PLANETS

8th gradeChapter 12

MERCURY

Mariner 10 1974-1975 Mariner flew by and sent back pictures to

Earth. Photographed only 45% of the planet. Many craters (like our moon) Cliffs Weak magnetic field around Mercury (Mariner

10) Traces of atmosphere….What was found and

why? Why does it have great extremes in

temperature? What is the extreme in temp.?

VENUS

Earth’s twin Mariner 2 ( 1962) sent back info on

atmosphere and rotation Venera 7—Soviet Union sent first probe 1970.

It stopped working in less than an hour..why?

More Venera probes—photographed, mapped the surface

1990-1994 Magellan probe used radar to make the most detailed maps of surface…radar images of 98% of surface.

Venus….continued

Dense clouds, only small amount of sunlight reaches surface

Sunlight that does get through, gives off heat and is absorbed by carbon dioxide gas in atmosphere.

This causes greenhouse effect…very intense.

Hottest planet

EARTH

Average distance from Earth to Sun is 150 million km or 1 astronomical unit.

Abundant liquid water Supports life Atmosphere protects from meteors

and radiation

MARS

Red planet because of iron oxide in soil on its surface

Polar ice caps---layer of frozen water covered by a layer of frozen carbon dioxide

Olympus Mons –largest volcano in solar system.

Seasons..what causes this? What causes the changing colors? What happens to the ice caps during the

seasons?

Mars---Viking Probes 1 and 2 1976 Each had an orbiter and a lander Photographed entire surface from

their orbits The landers carried equipment to

detect possible life on Mars upon landing.

Mars-Pathfinder

Carried a robot rover—Sojourner---with equipment that allowed it to analyze rock and soil

Data indicated that iron in the crust might have been from groundwater

Mars—Global Surveyor

Showed features that look like gullies …how did they form?

What do the scientists think about this?

Found atmosphere is much thinner that ours.

What is it composed of? What is the surface temperature

difference? What happens due to the

temperature difference?

Mars--Odyssey

Probe Detected frozen water The water occurs as frost beneath a

thin layer of soil Frost is common in the far northern

and far southern parts of Mars.

Martian Moons

Phobos, Deimos Heavily cratered Irregularly shaped Phobos has grooves and chains of

craters Deimos—among one of the smallest

—smoother in appearance

JUPITER

Composed mostly of ___________________

Atmosphere changes to an ocean of liquid hydrogen and helium toward middle of planet.

Maybe a rocky core Extreme pressure and temperature Continuous storms of high-pressure

gas Great Red Spot is huge storm

Moons of Jupiter

Table 2, p. 349 At least 61 moons Galileo first to see the largest moons What heats IO up causing it to be the

most volcanically active object in solar system?

Ganymede is largest moon in the solar system

Voyager probes revealed faint dust rings and IO’s volcanoes.

SATURN

Large, gaseous planet, thick outer atmosphere composed mostly of ________________________

Atmosphere changes to liquid, then rocky core

Voyager probes gathered new information about rings composed of countless ice and rock

How many rings?

Saturn--Moons

At least 31 moons Strong gravity holds the moons in

their orbits Titan is largest moon, bigger than

Mercury What else about Titan?

URANUS

Large, gaseous At least 21 moons 11 rings surround the equator Atmosphere made up hydrogen,

helium, some methane Methane gives the blue color Under atmosphere-mantle of liquid

water, methane, and ammonia Rocky core

Uranus---continued

Axis of rotation is tilted on its side---its parallel instead of perpendicular

Scientists believe there was a collision with another object.

Voyager 2 in 1986 Titania is largest moon

Many craters and deep valleys

NEPTUNE

Atmosphere similar to Uranus---methane absorbing red color

Dark colored storms—the Great Dark Spot (about the size of Earth)

Layer of liquid and rocky core Several rings At least 11 moons

Triton largest moon Thin atmosphere of nitrogen