Today's astronomers agree that our sister planet has no moons.

The three sister planets were moving into their major conjunction.

Alone among our sister planets, it is able to support a permanent human presence.

Venus is sometimes called the sister planet of Earth as they are quite similar in size and gravity.

You are a sister planet to we of the Pleiades.

Both had equal meaning to those who ruled from the sister planet.

"So all of a sudden the Romulans don't care who shows up around their sister planet?"

His ship entered the clouds that totally cover our sister planet, but never came out again.

Kepler-11d, along with its five sister planets, were announced to the public on February 2, 2011.

Kepler-11g is considerably farther away from Kepler-11 than its five sister planets.