Herrick produced the photograph.

“We haven’t had time to make up a slide,” said he, “so you will have to hand it round. You can see the black cloud, but it’s small on this picture, no more than a tiny globule. I’ve marked it with an arrow.”

He handed the picture to Emerson who, after passing it to Harvey Smith, said:

“It’s certainly grown enormously over the twenty years. I’m a bit apprehensive about what’s going to happen in the next twenty. It seems as if it might cover the whole constellation of Orion. Pretty soon astronomers will be out of business.”

It was then that Dave Weichart spoke up for the first time.

“I’ve two questions that I’d like to ask. The first is about the position of the cloud. As I understand what you’ve said, the cloud is growing in its apparent size because it’s getting nearer to us. That’s clear enough. But what I’d like to know is whether the centre of the cloud is staying in the same position, or does it seem to be moving against the background of the stars?”

“A very good question. The centre seems, over the last twenty years, to have moved very little relative to the star field,” answered Herrick.

“Then that means the cloud is coming dead at the solar system.”

Weichart was used to thinking more quickly than other people, so when he saw hesitation to accept his conclusion, he went to the blackboard.

“I can make it clear with a picture. Here’s the Earth. Let’s suppose first that the cloud is moving dead towards us, like this, from A to B.

Then at B the cloud will look bigger but its centre will be in the same direction. This is the case that apparently corresponds pretty well to the observed situation.”