“Questa è l’estate più calda degli ultimi 200 anni.” Chissà quante volte abbiamo sentito frasi simili. Ma come facciamo a sapere che temperatura c’era 200 anni fa? O ancora prima?...
Most astronomical observatories have records of meteorological observations, sometimes even complete series of data. Knowledge of the local weather is fundamental to ensure good astronomical observations (for example, to measure the angle of the atmospheric refraction)....
Magnetic fields are generated by electric currents. Just like many other celestial bodies, our planet has its own magnetic field, generated by the motions of the fluid outer core of the Earth, consequent to the Earth’s rotation on its axis....
When in 1788 the austrian government wanted a better map of the regions surrounding Milan and Mantua, which were then subject to the austrian empire, the job was given to the astronomers of the Brera Astronomical Observatory....