marco.caparrini's blog

Bayes' theorem relates the conditional and marginal probabilities of two random events:

32 suns orbiting the Earth?

Somehow ... yes! Let's try to demonstrate it ...

Do you remember those summer holidays, many years ago, when you took these two pictures, at sunset? I'm sure you do .... But: do you remember which of the two days was the windy day?

To answer to this question you just have to carefully look at the pictures. Did you find it out? Yes! You're right! The second day was windier!

For those who are not old salts: just look at the width of the sun glint. It is larger in the right hand picture (the one of the second day): this means that the sea surface was rougher and this in turn means that there was a higher wind speed blowing over the surface!

(Image: Artist's impression of GIOVE-A. Courtesy of ESA).

TRANSIT, GPS, GLONASS, Galileo, Compass... Since 1964, various different satellite-based navigation systems with global coverage have been deployed. The TRANSIT system, by USA, started its operational phase in 1964 (only for military purposes) and has been working until 1996. In 1993, the US GPS system began operations while the Russian GLONASS reached its completeness in 1995 (although nowadays, only 10 satellites are fully operational).