Ernesto Hernandez, age 7, of Tucson, Arizona, for his question:

Why is Venus sometimes so bright?

Sometimes golden Venus shines brighter than the brightest star. Sometimes it dwindles to a dim speck and disappears. No, our sister planet does not turn its golden light on and off. This seems to happen because the two planets act like merry go rounds. They never stop whirling along their orbits around the sun. If they traveled along side by side, Venus always would look the same size. But this does not happen.

Venus has the inside traffic lane and it orbits around a little bit faster. The earth travels a little bit slower. It also has farther to go around its larger, outside orbit. So the two planets are always changing their places. Venus catches up and passes us, pulls ahead and races around the far side of the sun. It shines brightest in our sky just before and just after it passes us. Then it dwindles away in the distance and, for a few nights, it hides behind the sun.