Great Conjunction of Jupiter & Saturn
Images of the Great Conjunction of Jupiter and Saturn on 21 December 2020 were taken with our India telescope, GJW-IN, just over an hour after closest approach which was just before local sunset. An animation showing their flypast from the day before to the day after is shown here.
The plane of Jupiter’s orbiting moons remains the same through out all these images (which have North up and East to the left). These moons orbit around Jupiter in the same way that the planets orbit around the Sun in the Solar System. The plane of Saturn’s rings, together with its moons, are different from the plane in which Jupiter’s moons orbit.
The first of these images, with Saturn starting in the top left, has three of Jupiter’s Galilean moons showing together with a star in the same line (Europa is transiting Jupiter during this observation). The middle image, with Saturn and Jupiter almost vertically aligned, shows three of the Galilean moons again but this time with Io occulted by Jupiter (and the whole system has moved relative to the background stars so that the first star which was to the left of Jupiter in the first frame is now seen to the right of Jupiter). The final image, with Saturn in the top right, shows all four of the Galilean moons with two shown on each side of Jupiter. Each image shows Saturn’s brightest moon, Titan, in orbit around it (in the first image it is to the right of Saturn, and by the final image it is almost above).
These are not easy observations to do, even if the skies are free of clouds (not the case at all our other observatories!). This is partly because Jupiter and Saturn were so close to the horizon, so the telescope is looking through lots of atmosphere which can sometimes be turbulent. This image shows how our finder scopes could see the conjunction, with the tops of trees threatening to get in the way!
These images were conducted by remote control over the internet of the GJW-IN telescope by Katherine Blundell in the UK and Steve Lee in Australia, made possible thanks to TeamViewer, Sophos, Zoom and Prism with a camera made by FLI. Sadly, the students cannot be on the campus of the school that hosts the GJW-IN observatory at present because of the worldwide pandemic, but we greatly look forward to their return and ours in due course.
Jupiter's Galilean moons and their orbits are described in Katherine Blundell’s Inaugural Gresham Lecture “Faster than Light?” <YOUTUBE LINK> and the Great Conjunction is described in the "Witnessing Fireworks" Gresham lecture <YOUTUBE LINK>. Alternative (non-YouTube) links are HERE.