MOONS

Of our solar system

What is a Moon?

• A natural satellite is an object that orbits a planet or other body Larger than itself and which is not man-made. Such objects are often called moons.

• (moons as a group are called “natural satellites” the only true “moon” is earth’s moon, no other natural

satellite is named that.)

Earth’s Moon

• Earth’s only natural satellite; The moon is:• The moon is 238900 miles from the earth.• Does not give off it’s own light, it reflects light from the sun.• The moon is geologically dead. There is no atmosphere,

and no forces of erosion.• The moon has no magnetic field.• The moons surface is pocked with craters because of

hundreds of thousands of meteor impacts.• The moon takes about 1 month to complete its orbit, and

during that time, it goes though phases, where some of the moon is not reflecting the light from the sun

Earth’s Moon: Cont’d

• The moon is 1/4th • earth’s radius,• and has 1/6th

• its gravity. • • The moon rotates• around the earth• every 27.5 days

How Many Natural Satellites are There in Our Universe

• There are 168 known natural satellites in the solar system, all varying in size, composition, orbit, and even shape.

• Every planet has a moon except for mercury and Venus

How Big are Most Natural Satellites?

Mars’ Moons

• Mars has two moons, Phobos and Demios.• These are not actually moons, they are minor

satellites. They are small chunks of rock that were caught in Mars’ gravitational pull

Jupiter’s Moons

• Jupiter’s moons were nicknamed “the Galilean satellites, after the famous astronomer of the same name.

• Jupiter has four large moons, Io, Europa, Ganymede, and Callisto. It has many more, but these our are the biggest.

• All of these moons are EXTREMLEY different

Io

• Io is the most volcanically active entity in the solar system. Constant volcanic activity on it’s surface has made the moon’s atmosphere almost pure sulfur.

• Io is the third largest of Jupiter’s moons and is the fifth furthest from the planet.

• The same side of Io always points to Jupiter.• Ganymede affects Io’s abundance of molten rock in

the same way that our moon does with the oceans, as in it shifts their depth and position

Europa

• Because it is so far away from the sun, Europa’s surface is comprised mainly of ice. Under that is a vast, salt water ocean that covers the entire planet.

• Europa’s composition is very similar to earth’s in it form. It has a crust, a mantle and an iron core.

• Just like Io, Europa is “phase locked” witch means that the same side is facing it’s parent planet at all times.

Ganymede

• Ganymede is our solar systems largest natural satellite

• It is the only NS that has it’s own magnetic field

• Ganymede’s crust, like Europa’s is composed mainly of ice. The only difference is that Ganymede’s crust is around 500 miles deep

Callisto

• Callisto has a diameter of 2985 miles, and it is the third largest natural satellite in the solar system. It is almost a big a mercury.

• It is the further away than any other moon from Jupiter.

• Callisto is twice as bright as our moon.• It is around four billion years old.