Pro­fes­sor Gerry Gil­more

Australian T3 - - OPINION -

gaia project’s lead in­ves­ti­ga­tor spills the space beans

So how does Gaia’s bil­lion­pixel snap­per work?

The in­di­vid­ual sen­sors are, in prin­ci­ple, sim­i­lar to the ones in a commercial cam­era. There are 106 in to­tal, each ten-meg, and they can see an ob­ject the di­am­e­ter of a hu­man hair from 1,000km away. That’s the equiv­a­lent of be­ing able to tell the dif­fer­ence be­tween the left and right side of a shirt but­ton on the Moon.

Why do we need such a sen­si­tive cam in space?

Gaia will mea­sure the lo­ca­tion of one bil­lion stars in three di­men­sions. By do­ing this 80 times on aver­age for all of the Milky Way’s bil­lion stars over five or six years, we’ll be able to re­con­struct how the galaxy was as­sem­bled. We think it was formed from a large num­ber of small gal­ax­ies com­ing to­gether and if we mea­sure the or­bits we’ll find out.

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