Add Yahoo as a preferred source to see more of our stories on Google. This video takes viewers on a long journey from the diminutive Speck of Horton Hears a Who (diameter 0.9 mm) all the way up to the ...

Bigger than a planet? Smaller than an atom? Size comparison videos are all the rage and may scratch a very old itch. By Jenny Marder Not long ago, my 7-year-old son looked up from a picture he was ...

In the 1990s, astronomers confirmed the first planets orbiting stars beyond our sun. Since then, the tally has risen steadily, and last year it crossed a striking milestone: more than 6,000 known ...

There’s something about comparing the sizes of unthinkably large objects that’s endlessly intriguing. Looking at a comparison of all the various sizes of stars in the universe, for example, makes for ...