Adrian Dening's Stars Over Somerset

Wednesday, 8 September 2021 17:00

Monday 13th to Sunday 19th September 2021

On Wednesday 15th at around 11.40pm, there is a good opportunity to observe the Great Red Spot on Jupiter with your telescope. Jupiter will be located to the south, with Saturn and its amazing rings to the right of it and a setting Gibbous Moon further right again.

Jupiter spins very fast - a day and night, or in technical terms the sidereal period, only lasts ten hours. This can make the Great Red Spot hard to see as very often, when you are observing the planet, the spot is round the wrong side! You are actually looking at a huge storm that is at least 350 years old, with wind speeds approaching 300 miles per hour. It is so enormous that a couple of Earths would fit inside it!

The first close-up view of the spot came from the Voyager 1 space probe that flew past Jupiter back in 1979. After its fly-by, Voyager 1 headed away from the Solar System and in 2012 it left the Heliosphere which is defined as the furthest distance where things are influenced by our Sun. Now the probe is approximately 14 billion kilometers away from Earth, travelling through the Interstellar Medium.

Because it is so far away, radio signals from the probe take the best part of a whole day to reach us. It is estimated that by 2025, its little nuclear reactor that powers everything will be exhausted and we will then lose contact with it.

Both Voyager 1 and its sister probe, Voyager 2, contain a golden record that contains sounds and photos of Earth - maybe one day it will be discovered by an alien civilisation!

Screenshot courtesy of Stellarium
Copyright Adrian Dening and Radio Ninesprings 2021