Childrens Illustrated Encyclopedia

355

Luna 3

until 1959, the far

side of the moon

had never been seen.

In October of that year, the

Russian space probe Luna 3

(right) sent back the first

photographs of this part

of the moon.

BIRth Of the mOOn

there have been many theories

to explain the formation of the

moon. Scientists have suggested

that the moon may be a piece of

earth that broke away millions of

years ago. today, however, most

astronomers believe that the moon

was formed when an asteroid the

size of mars struck earth about

4.5 billion years ago.

OuR neaReSt neIghBOR in space is the moon.

It orbits, or circles, earth keeping the same face

pointed toward us. the moon is a hostile place.

It has no atmosphere to keep the temperature

fairly constant, as earth does. Instead,

temperatures range from a scorching 240°f

(115°C) during the moon’s day to an icy -260°f

(-160°C) at night. there is no water, so no

plants or animals can live there. great plains

stretch over the moon’s surface, dotted with

huge mountains and scarred by numerous

craters. the moon does not produce light of

its own. We see the moon because it acts like a

huge mirror, reflecting light from the sun. the

moon is a natural satellite—something that orbits

around a planet or a star. there are many moons

circling the other planets in the solar system.

Other mOOns

Our solar system contains more than

150 known moons. nearly all circle

the giant outer planets and are

made of ice mixed with rock.

the largest planet, Jupiter, has

at least 63 moons, three of

them larger than our own

moon. One, Io (seen

alongside Jupiter, left), is

alive with active volcanoes.

another, ganymede, is

the largest satellite in the

solar system. Some of

Saturn’s moons are very

small and orbit in the

outer sections of the

planet’s rings.

LunaR LandIngS

In 1966, the Russian Luna 9 spacecraft made

the first controlled landing on the moon. It

was only three years later, in July 1969, that

american astronaut neil armstrong climbed

down from the apollo 11 lunar module to

become the first person on the moon.

Armstrong’s

crew member,

Edwin Aldrin, stands

by the lunar module.

PhaSeS Of

the mOOn

as the

moon orbits

earth,

different

phasess,

or shapes,

appear,

depending

on the

amount of the

sunlit side of

the moon that is

visible from earth.

1 New moon

(moon

invisible)

5 Full

Moon

7 Half moon

(last quarter)

The gravitational attraction

of the moon causes tides to

rise and fall in Earth’s oceans.

Lava once flowed from the

moon’s interior, following

huge meteorite impacts

more than 4,000

million years ago.

The lava solidified

into smooth-

floored plains

called seas,

or maria.

Craters

were formed

by meteorite

impacts. A few

are a result of

volcanic activity

within the moon.

2 Crescent

moon

4 Gibbous

moon (waxing)

6 Gibbous

moon (waning)

8 Old

moon

3 Half moon

(first quarter)

Moon

mOOn facts

Distance 238,855 miles

from earth (384,401 km)

Diameter at 2,160.5 miles

equator (3,477.8 km)

time for 27 days,

each orbit 7 hours,

43 minutes

time between 29 days,

full moons 12 hours,

43 minutes

Gravity at 1/6 of earth’s

surface surface gravity

Brightness 1/425,000

brightness

of sun

Find out more

astronomy

earth

Oceans and seas

Planets

Space flight

Moon seen

from here

2

3

4

5

6

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US_355_Moon.indd 355 09/02/16 3:57 pm