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EarthMarsVenusPlanet Pictures
space technology has shown
us what the other planets in
the solar system look like and
what they are made of; it has
also established that these
other planets are unlikely
to support life. the images
shown right and at the bottom
of the next page were taken
from a variety of spacecraft.The heavily cratered surface
of Mercury is revealed in this
photograph taken by the
MESSENGER spacecraft.Photograph taken by the
Pioneer-Venus probe shows
thick yellowish clouds covering
the surface of Venus.Picture of Earth taken by the
Meteosat weather satellite.
Colors have been enhanced
using a computer.This snapshot of Mars was
created from a series of
images taken by NASA’s
Hubble Space Telescope.earth is one of eight major planets moving around the sun. Planets are large
balls of rock, metal, gases, and liquids orbiting a star. in our solar system, all the
planets travel in the same direction around the sun, each revolving in an elliptical
(oval) orbit. through a telescope, the planets appear as disks of light moving slowly
across the night sky. they do not, however, produce light themselves, but reflect
light from the sun. all the planets except Mercury are surrounded by a layer of
gas called an atmosphere. the four smaller planets, such as earth, have a rocky
surface, but the four giant planets are mostly gas and liquid. the giant planets
are each surrounded by rings. there is a huge difference in temperature
between the planets nearest to the sun and those farthest away. Mercury is hotter
than an oven by day, while neptune is about 392°F (200°c) below freezing. as
far as we know, earth is the only planet that
supports life. however, the sun is one
of billions of stars, and planets
have already been discovered
orbiting thousands of them.
another planet somewhere
might support life.Mercury
Mercury is too small and
gets too hot to have an
atmosphere or oceans.
it has a rocky surface that
rises to a temperature of
about 662°F (350°c).the sun
the sun is a star—a vast
ball of hot gas, far larger
than any of the planets.JuPiter
Jupiter is
the largest
planet in the
solar system.
it has no solid
surface since it is
made mainly of
liquid hydrogen
blending into a layer of
swirling gas forming an
atmosphere around it. it is a cold
planet, surrounded by a ring of dust,
and orbited by more than 60 moons.asteroids
thousands of tiny bodies called asteroids orbit
the sun, mainly traveling in a belt between
Mars and Jupiter. dating from the earliest days
of the solar system, most asteroids are lumps
of rock and metal just a few miles in diameter.
Jupiter’s gravitational pull can send asteroids
into erratic orbits, causing them to collide
with planets and other asteroids. Many objects
made of ice and rock are also known to exist
in the Kuiper Belt, an area in the solar system
beyond the orbit of neptune.Venus
Venus is covered by
thick clouds. its dense
atmosphere traps the sun’s
heat and makes Venus the
hottest planet in the solar
system. the surface
temperature of Venus
is about 896°F (480°c).The moonearth
earth has an atmosphere of air and
oceans filled with water. earth’s
average temperature is 72°F (22°c).
a source of energy and liquid water
are essential for life on the planet.
if earth were hotter, the water
would evaporate; if it were colder,
the water would freeze.Mars
Mars is a small, dry planet with a red,
rocky surface. it is cold—about -9°F
(-23°c)—and has two polar caps of
ice and frozen gas. Mars has two tiny
moons named Phobos and deimos.Planets 409-
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