Mercury:
The
Fastest
Planet
in
the
Solar
System Mercury,
named
after
the
Roman
messenger
god,
is
the
smallest
and
innermost
planet
in
the
solar
system.
It
is
also
the
planet
closest
to
the
sun,
with
an
average
distance
of
36
million
miles.
Despite
its
small
size
and
close
proximity
to
the
sun,
Mercury
is
an
interesting
planet
that （浏览更多 今日星座运势查询文章请关注 :兰花星座网,wWw.iLanHua.cC」」
holds
many
secrets. With
a
diameter
just
under
3,000
miles,
Mercury
is
only
slightly
larger
than
Earth’s
moon.
It
is
also
one
of
the
densest
planets
in
the
solar
system,
meaning
that
its
core
is
proportionally
larger
than
those
of
the
other
planets.
The
core
is
believed
to
be
composed
mostly
of
iron,
and
theories
suggest
that
part
of
the
core
may
be
molten. One
of
the
most
striking
features
of
Mercury
is
its
surface.
The
planet
is
heavily
cratered,
and
its
rocky
terrain
is
marked
by
long
cliffs
and
valleys.
With
a
surface
temperature
that
can
reach
up
to
800°F
during
the
day
and
drop
to
-290°F
at
night,
Mercury
is
a
harsh
planet
to
inhabit.
However,
it
is
believed
that
water
ice
may
exist
in
some
of
the
permanently
shadowed
craters
at
the
planet’s
poles. Mercury
is
also
known
for
its
unique
rotation.
It
takes
88
Earth
days
for
Mercury
to
complete
one
orbit
around
the
sun,
but
it
rotates
on
its
axis
in
just
59
Earth
days.
This
results
in
a
phenomenon
known
as
“rotation
resonance.”
Essentially,
Mercury
rotates
three
times
for
every
two
orbits,
which
means
that
from
the
perspective
of
an
observer
on
the
planet,
the
sun
appears
to
go
through
a
“day”
that
lasts
two
Mercurian
years. Despite
being
the
closest
planet
to
the
sun,
Mercury
is
not
the
hottest
planet
in
the
solar
system.
Because
of
its
lack
of
atmosphere
and
slow
rotation,
the
temperature
on
Venus
can
exceed
864°F. Overall,
Mercury
is
a
fascinating
planet
with
a
wealth
of
unique
characteristics.
While
humans
are
unlikely
to
set
foot
on
its
harsh
surface
anytime
soon,
further
exploration
and
study
of
the
planet
may
yield
important
insights
into
the
formation
and
evolution
of
the
solar
system.