21.   Recent images reveal dust discs swirling around a collection of two dozen young stars, a prelude to the formation of planets, astronomers believe.

22.   Stern said the images of Pluto strengthened arguments that it was a true planet, as most astronomers believe.

23.   Such motion is impossible and astronomers believe they understand how the illusion is created.

24.   The finding suggests that the pulsar Chandra detected is much younger than astronomers had once believed, offering new insight into the way stars die.

25.   The infrared glow, the astronomers believe, comes primarily from clouds of dust warmed by the stars.

26.   Though it currently displays no cometary activity, some astronomers believe it may be the dead nucleus of an ancient comet.

27.   What some astronomers believed to be the only planet ever directly observed outside the solar system has turned out to be an ordinary dim star, NASA announced Thursday.

28.   Astronomers believe a star forms from a rotating cloud of dust and gas.

29.   Astronomers believe the process began after the Big Bang, thought to be the origin of the universe.

30.   Astronomers believe the universe was created in an immense explosion and that lots of hydrogen gas and much less helium gas ultimately were spread between galaxies.