|
|
What path do the planets take across the sky?
Home » Astronomy » Learning the Night Sky » What path do the planets take across the sky?The planets orbit the Sun like clockwork on an imaginary path called the ecliptic—the same basic path the Moon and Sun take across our visible skies. Picture our solar system from above. In the center is our Sun and around it the planets move along their own race tracks. The planets close to the Sun orbit faster and their track is smaller, while outer planets move slower and their track is longer—Kepler’s law in action.
Venus and Mercury whiz by the Earth several times a year, hiding in front of or behind the Sun. Earth is chasing them, but on a longer track. Outside are Mars, the asteroid belt, Jupiter, Saturn, Uranus, Neptune and Pluto. We are all on the same flat plane. Sometimes the Sun is between Earth and the outer planets. When the inner planets pass the Earth, or the Earth passes the outer planets, something very extraordinary happens: retrograde motion. Picture yourself in a moving car coming up on another vehicle. As you approach, the other car seems to slow down, stand still and then move backwards. This is how retrograde motion works!
Related Learning the Night Sky Articles
- Are the stars always the same?
- What path do the planets take across the sky?
- What path do the Moon and Sun take across the sky?
- Why does the Moon have phases?
- Introduction to the Night Sky