There are nine planets travelling around the sun, the earth being one of them.
The planets revolve around the sun.
The earth is different from the other planets in that it has water.
Scientists can easily compute the distance between planets.
Seen through a telescope, the planets take on a completely new appearance.
The sun has nine planets.
J. Kepler, astronomer and mathematician, made a study of planets and their movements.
Can you tell me instead, why the planets on the screen are coloured the way they are?
My very educated mother just showed us nine planets.
He is always writing about journey to other planets.
He won't let you in unless you knock the ostinato rhythm from the Mars movement of Holst's The Planets suite.
In 2006, the International Astronomical Union decided to create a new category for solar system objects called "dwarf planets", and Pluto was reclassified as a dwarf planet.
The smaller planets hovering around the planet Jupiter reminded him of the guards surrounding a king when he walked outdoors, and Kepler called them satellites.
Do other planets exist, on which life can exist?
Planets are easy to identify because they don't twinkle like stars do.
English word "行星"(planets) occurs in sets:Planets in Chinese