4th grade Science Vocab - 11/17/25

Science Vocab - space/orbit

axis

an imaginary straight line that a planet or other object spins around. For Earth, the axis runs through the North pole and South pole

constellation

a group of stars that form a pattern in the sky and have a name, like Orion or Ursa Major

eclipse

an event when one object in space moves into the shadow of another. A solar eclipse happens when the moon blocks the sun; a lunar eclipse happens when Earth blocks sunlight from reaching the moon.

ellipse

a stretched-out circle (oval) shape.  Planetary orbits are ellipses, not perfect circles

moon

a natural object that orbits (travels around) a planet. Earth’s moon is the object we see changing shapes in the night sky.

moon shapes

the different visible portions of the moon as seen from earth during its cycle. (examples: new moon, crescent, quarter, gibbous, full moon)

orbit

the curved path one object takes around another because of gravity. (example: earth orbits the sun; the moon orbits Earth)

phase

one stage in the moon’s cycle that shows how much of the moon’s lit side we can see from Earth (example: full phase, new phase)

revolution / revolve

to travel once around another object. One revolution of Earth around the sun takes about one year.

star / star patterns

a star is a huge, glowing ball of gas that makes its own light and heat. (the sun is a star)

Star patterns are groups of stars people recognize as shapes (some are constellations)

rotation / rotate

to spin once around an object’s own axis.  One rotation of Earth (one spin) takes about one day. 

tilt

the angle at which a planet’s axis leans compared to the path it follows around the sun. Earth’s tilt causes the seasons.

year

the time it takes a planet to complete one full revolution around the sun. For Earth, one year is about 365 days.