Frank McCawn, aged 13, of Kingston Springs, Tenn., for his question:

Which of the nine planets gets the hottest?

We would expect the highest temperature of the nine planets to occur on the planet nearest the sun, And this is so, At times, little Mercury is only about twenty‑eight and a half million miles from our blazing star. This closeness to the sun effects the rotation, the revolution and the temperature of the inside planet. Its rotation around its axis is slowed down. Its revolution around the sun is speeded up. In places its temperature is hot enough to melt lead. In other places is is almost as cold as outer space.

For little Mercury turns only once on its axis as It circles the sun One side forever faces the sun. The other side faces eternally away from the sung Its day equals its year. Both are 88 of our days long. It speeds around its orbit between 23 and, 36 miles a second.

Mercury has no atmosphere to modify the rays of the sun or to protect it from the cold of empty apace. Its dayside is forever hot. Its nightside is forever cold. Daytime temperatures are estimated to be about 350 degrees Centigrade. The temperature of the nightside may be almost as low as minus 273 degrees Centigrade. This temperature is absolute zero ‑ which is as cold as anything can possibly get