UNIT 2
THE SOLAR SYSTEM
Vocabulary Review
THE FORCE OF ATTRACTION BETWEEN
OBJECTS THAT IS DUE TO THEIR MASSES
gravity
THE PATH THAT A BODY FOLLOWS AS
IT TRAVELS AROUND ANOTHER BODY
IN SPACE
orbit
IN THE ORBIT OF A PLANET OR ANOTHER
BODY IN THE SOLAR SYSTEM, THE POINT THAT
IS CLOSEST TO THE SUN
perihelion
IN THE ORBIT OF A PLANET OR ANOTHER
BODY IN THE SOLAR SYSTEM, THE POINT THAT
IS FARTHEST FROM THE SUN
aphelion
THE INWARD FORCE REQUIRED TO KEEP A
PARTICLE OR AN OBJECT MOVING IN A
CIRCULAR PATH
centripetal force
A ROTATING CLOUD OF GAS AND DUST FROM
WHICH THE SUN AND PLANETS FORMED
solar nebula
A SMALL BODY FROM WHICH A PLANET
ORIGINATED IN THE EARLY STAGES OF THE
SOLAR SYSTEM
planetesimal
THE PROCESS BY WHICH THE NUCLEI OF SMALL
ATOMS COMBINE TO FORM A NEW, MORE
MASSIVE NUCLEUS; THE PROCESS RELEASES
ENERGY
nuclear fusion
A DARK AREA OF THE PHOTOSPHERE OF THE SUN
THAT IS COOLER THAN THE SURROUNDING AREAS
AND THAT HAS A STRONG MAGNETIC FIELD
sunspot
A LOOP OF RELATIVELY COOL INCANDESCENT
GAS THAT EXTENDS ABOVE THE PHOTOSPHERE AND
ABOVE THE SUN’S EDGE AS SEEN FROM EARTH
prominence
AN EXPLOSIVE RELEASE OF ENERGY THAT COMES
FROM THE SUN AND THAT IS ASSOCIATED WITH
MAGNETIC DISTURBANCES ON THE SUN’S SURFACE
solar flare
ONE OF THE HIGHLY DENSE PLANETS
NEAREST TO THE SUN
terrestrial planet
A UNIT OF MEASURE EQUAL TO THE AVERAGE
DISTANCE BETWEEN THE EARTH AND THE SUN;
APPROXIMATELY 150 MILLION KM
astronomical unit
A PLANET THAT HAS A DEEP, MASSIVE
ATMOSPHERE, SUCH AS JUPITER, SATURN,
URANUS, AND NEPTUNE
gas giant
A DISK OF MATTER THAT ENCIRCLES A PLANET AND
THAT CONSISTS OF NUMEROUS PARTICLES IN ORBIT,
WHICH RANGE IN SIZE FROM DUST GRAINS TO
OBJECTS TENS OF METERS ACROSS
planetary ring
A CELESTIAL BODY THAT ORBITS THE SUN, IS
ROUND BECAUSE OF ITS OWN GRAVITY, BUT
HAS NOT CLEARED ITS ORBITAL PATH
dwarf planet
A REGION OF THE SOLAR SYSTEM THAT STARTS
JUST BEYOND THE ORBIT OF NEPTUNE AND
THAT CONTAINS DWARF PLANETS AND OTHER
SMALL BODIES MADE MOSTLY OF ICE
Kuiper Belt
ONE OF THE HUNDREDS OR THOUSANDS OF
SMALL BODIES THAT ORBIT THE SUN IN A FLAT
BELT BEYOND NEPTUNE’S ORBIT; ALSO
INCLUDES DWARF PLANETS LOCATED THERE
Kuiper Belt object
A SMALL BODY THAT GIVES OFF GAS AND DUST AS
IT PASSES CLOSE TO THE SUN; IT MOVES IN AN
ELLIPTICAL ORBIT AROUND THE SUN AND IS MADE
OF DUST AND FROZEN GASES
comet
A SPHERICAL REGION THAT SURROUNDS THE
SOLAR SYSTEM THAT EXTENDS FROM THE KUIPER
BELT TO ALMOST HALFWAY TO THE NEAREST STAR,
AND THAT CONTAINS BILLIONS OF COMETS
Oort cloud
A SMALL, ROCKY OBJECT THAT ORBITS THE
SUN; MOST ARE LOCATED IN A BAND
BETWEEN THE ORBITS OF MARS AND JUPITER
asteroid
A RELATIVELY SMALL, ROCKY BODY THAT
TRAVELS THROUGH SPACE
meteoroid
A BRIGHT STREAK THAT RESULTS WHEN A
METEOROID BURNS UP IN EARTH’S
ATMOSPHERE
meteor
A METEOROID THAT REACHES EARTH’S
SURFACE WITHOUT BURNING UP COMPLETELY
meteorite
Well done!