- explore = investigate or survey
- elliptical = oval , egg shape
- spacecraft = space ship
- center = middle, heart, core
- essential = necessary
- spin = twist
- average = standard
Exploring the night skies, astronomers point out the universe contains round, oval or spiral-shaped galaxies that are made up of stars, planets and other bodies. Telescope and spacecraft have been use to identify over a hundred galaxies including the Milky way, the galaxy our sun and planet belong to.
In the center of our planetary system, lies a star that we call the sun. The sun provides us with heat and light essential. Textbooks also mention 9 other planets in our solar system. All planets are spherical, and orbit our sun in the same direction. Mercury lies closer to the sun, followed by Venus, Earth, Jupiter, Saturn, Uranus, Neptune, and Pluto.