During which season in the Northern Hemisphere is the earth at its farthest distance from the sun?


A.
spring


B.
winter


C.
autumn


D.
summer

Which force holds the planets in their orbits?


A.
electromagnetism


B.
strong nuclear force


C.
weak nuclear force


D.
gravity

What is the name for a star and planets held together by gravity?


A.
solar system


B.
galaxy


C.
black hole


D.
supernova

Which contribution did Kepler make to our view of the solar system?




A.


He proposed that gravity kept the planets in their orbits.


B.


He proposed the sun-centered model of the solar system.


C.


He proposed the earth-centered model of the solar system.


D.


He showed that planets moved in elliptical orbits.
plz help :(