Their host and the two astronomers, after a certain amount of quiet discussion, accepted their invitation to accompany them, and on the morning of the eighth day after their landing on Ganymede, the _Astronef_ rose from the plain outside the Crystal City, and directed her course towards the centre of the vast disc of Jupiter.
She was followed by the telescopes of all the observatories until she vanished through the brilliant cloud-band, eighty-five thousand miles long and some five thousand miles broad, which stretched from east to west of the planet.

At the same moment the voyagers lost sight of Ganymede and his sister satellites.
The temperature of the interior of the _Astronef_ began to rise as soon as the upper cloud-belt was passed.

Under this, spread out a vast field of brown-red cloud, rent here and there into holes and gaps like those storm-cavities in the atmosphere of the Sun, which are commonly known as sun-spots.

This lower stratum of cloud appeared to be the scene of terrific storms, compared with which the fiercest earthly tempests were mere zephyrs.
After falling some five hundred miles further they found themselves surrounded by what seemed an ocean of fire, but still the internal temperature had only risen from seventy to ninety-five.

The engines were well under control.