Gary Karr, aged 13, of Clendenin, W. Va., for his questions

How long is a day on the planet‑Pluto?

Telescopes show that other planets besides our earth shin around on a central axis. We call one complete rotation a day and night period. The planets spin at various speeds. So the length of the day and night is different for each of them.

Little Mercury rotates once in about 88 of our days, The giant planets seem to spin faster. Jupiter, Saturn and Uranus have day and night periods lasting less than 11 of our hours, Neptune rotates once in about eleven and a half hours.

Experts figure these periods from marks on the faces of the planets. So the telescopes must be able to see the face of a planet before we can figure its dry and night period. Venus, no doubt has a day and night period. But what it is we do not know. For Venus is veiled in clouds too dense to revel, its face.

Little Pluto's day and night period is six earth days nine hours and 17 minutes.  It is a very small planet and seldom comes closer to us than 3,600 million miles. Our telescopes are pretty  good ‑ but they are not good enough to spot details on the face of a little planet so far away. Perhaps the Hubble telescope will give us better views of this distant body.