radually
going further and further, seeking a planetary system. This is probably
the one and only one they found. It's a good one too. It has planets at
all temperatures, of all sizes. It is a fairly compact one, it has a
stable sun that will last far longer than any race can hope to."

"Hmm--how can there be good and bad planetary systems?" asked McLaurin.
"I'd never thought of that."

Kendall laughed. "Mighty easy. How'd you like to live on a planet of a
Cepheid Variable? Pleasant situation, with the radiation flaring up and
down. How'd you like to live on a planet of Antares? That blasted sun
is so big, to have a comfortable planet you'd have to be at least ten
billion miles out. Then if you had an interplanetary commerce, you'd
have to struggle with orbits tens of billions of miles across instead of
mere millions. Further, you'd have a sun so blasted big, it would take
an impossible amount of energy to lift the ship up from one planet to
another. If your trip was, say, twenty billions of miles to the next
planet, you'd be fighting a gravity as bad as the solar gravity at Earth
here all the way--no decline with a little distance like that."

"H-m-m-m--quite true. Then I should say that Mira would take the prize.
It's a red giant, and it's an irregular variable. The sunlight there
would be as unstable as the weather in New England. It's almost as big
as Antares, and it won't hold still. Now that _would_ make a bad
planetary system."

"It would!" Kendall laughed. But as we know--he laughed too soon, and he
shouldn't have used the conditional. He should have said, "It does!"

III

Gresth Gkae, Commander of Expeditionary Force 93, of the Planet Sthor,
was returning homeward with joyful mind. In the lock of his great ship,
lay the T-247. In her cargo holds lay various items of machinery, mining
supplies, foods, and records. And in her log books lay the records of
many readings on the nine larger planets of a highly satisfactory
planetary system.

Gresth Gkae had spent no less than three ultra-wearing years going from
one sun to another in a definitely mapped out section of space. He had
investigated only eleven stars in that time, eleven stars, progressively
further from the titanic red-flaming sun he knew as "the" sun. He knew
it as "the" sun, and had several other appellations for it. Mira was
so-named by Earthmen because it was indeed a "wonder" star, in Latin,
mirare means "to wonder." Irregularly, and