___ orbital point nearest the sun.

___ a tide just after a new or full moon, when there is the greatest difference between high and low water.

Earth has ___ because because its axis is tilted as it moves around the sun.

___ planets revolve around the sun at varying speed.

___ the movement of an object around another object.

___ wobbling of the Earth's axis that is superimposed on Earth's precession.

___ an imaginary line that passes through Earth's center and the North and South poles, about which Earth rotates.

___ point in a planet's orbit that is farthest from the sun.

___ every object attracts every other object with a force that is proportional to the product of the two masses and inversely proportional to the square of the distance between them.

___ the center of mass of two or more bodies orbiting around each other.

___ occurs when the Moon passes directly between the Sun and Earth and casts a shadow over part of Earth.

___ the blocking of sunlight to the moon that occurs when Earth is directly between the sun and the moon.

___ a regular oval shape, traced by a point moving in a plane so that the sum of its distances from two other points is constant, or resulting when a cone is cut by an oblique plane which does not intersect the base.

___ the farther a planet is from the focus, the longer the period of revolution.

___ a slow motion of Earth's axis that traces out a cone over a period of 26,000 years.

___ Planets move in elliptical orbits with the sun at one of the foci.

___ a force of attraction between objects that is due to their masses.

___ the spinning of Earth on its Axis.

___ creation of energy by joining the nuclei of two hydrogen atoms to form helium.