For the last few days, Venus and Jupiter have been very close together in the evening sky. I wanted to take photos on Wednesday and Thursday, but it was cloudy. I wished I’d asked to go up to the observatory, above the clouds. Lucky me, I got permission to go there on Friday evening to take photos. I’m really glad I made the effort.
Francesco Pepe invited me to see inside the HARPS spectrograph. I was very lucky, because the enclosure was closed for the inauguration, and closed again (probably for years) soon after I took these photos. Of course I had to wear special over-clothes to prevent dust getting into the instrument. The top photo shows the grating, which splits the starlight into a rainbow, and the bottom one shows the collimator,…
The HARPS-N spectrograph was inaugurated on April 23rd. Here’s some photos. This write up is better late than never, I hope.
The big telescopes at the observatory at the Roque de Los Muchachos mostly use mirrors rather than lenses. Domestic mirrors have the aluminium behind glass to protect it, but astronomical mirrors have the aluminium on top. This gives the best image, but it also means that the aluminium slowly spoils, and has to be replaced every three years or so. This is not a simple operation. The aluminium layer is…