The Bridge V Learning Edition 1 ; our solar system | Page 4

T he se p lan e ts tha t o rb i t o the r s ta rs a re call ed ex tra so la r pl an e ts . In re ce n t
ye a rs , a s tro nome rs ha ve f ou nd tho usa nd s of the se an d reg ul arly d i sc o ver
mo re . H o we ve r we k no w ve ry li ttle a bo u t them bu t i t se ems lik e ly th a t e ve ry
s ta r h as i ts o wn p lane t s ys tem.
T he re a re two type s of pl ane ts i n o ur Sol ar S ys tem: ro ck y pla ne ts , wh ic h a re
g en e rall y n ea r the S un , Mercu ry, Ve nu s , Ea rth a nd Ma rs . Th en th e re a re g as
g ian ts , whic h a re m ore m as si ve a nd mai nl y c ompo se d of ga s . T he se a re
J up i te r, S a tu rn , U ranu s a nd N ep tune m ak e u p th e l a tte r.
Pl u to i s con sid e re d a d wa rf pl an e ts sin ce 2 00 6 . Be twee n Ma rs a nd Ju pi te r i s
th e a s te roid bel t, whic h c i rcl es the S un l ike a rin g . It co nsi s ts of tho u sa nd s of
sm alle r an d la rge r rock s . Th e la rge s t of the se ha ve thei r o wn name s , j us t lik e
th e p lan e ts . One of th em , Ce re s , i s s o la r g e th a t i t i s con sid e re d a d wa rf
p lan e t.
The planets
Pl an e ts and d wa rf pla ne ts a re s phe rica l an d o rbi t a s ta r. C u rren tl y (i n 2 017 )
fi ve d wa rf p lan e ts have b ee n id en tif ie d : Ce res , P lu to , Haum ea , Mak emak e and
E ri s . Moo ns a re of ten s ph e ric al as we ll , d ep en din g o n th ei r si ze, b u t the y o rbi t
p lan e ts .
E ach of the p lan e ts in ou r S ola r S ys tem ha s i ts o wn fe a tu re s . W e ha ve
s umma ris ed them in th e fa c t fil es bel o w.