Bigger, hotter, farther

A few hints, to guess right more often

The farther a body is from the Sun, the longer it takes to go around it and the colder it is: both are true almost every time, and on their own they answer a lot of questions. And big does not mean heavy: Saturn is the second-largest planet in the Solar System, but the stuff it is made of weighs 687 kilograms per cubic meter, less than the 1,000 of water. If there were a bathtub big enough, it would float.

One number works backward, and it helps to know before you get it wrong: magnitude. The smaller the number, the easier the object is to see. Sirius, the brightest star in the sky, is at -1,46; a star of magnitude 6 is at the limit of what the eye can catch.

And to see how big it really is: the size comparison tool