Jupiter's Great Red Spot is shrinking!

Jupiter's Great Red Spot is shrinking!

by Brendan Owens

Bjorn Jonsson An image captured by Voyager 1 in 1979, but greatly enhanced by Bjorn Jonsson.

Most of the planets in our Solar System have a signature feature that makes them easy to recognise. For example: Saturn has its vibrant rings, Mars has its polar ice caps, and Jupiter is famous for the Great Red Spot – a huge storm of swirling gas clouds. However this anti-cyclonic storm is not as huge as it once was…

The Great Red Spot is shrinking! Astronomers have noticed the change since the 1930s, but since 2012 the storm has been shrinking faster and faster. We used to say that three planet Earths can fit across the Great Red Spot, but now we can’t even fit one and half Earths across it! It’s still pretty big as far as storms go, but why it is shrinking is still a bit of a puzzle for astronomers. It seems that little swirls of gas called eddies are feeding into the Great Red Spot and influencing how it moves causing a faster change in its size.

The storm is losing 933km of its width every year in recent years so in less than 18 years there may no longer be a Great Red Spot to see. Interestingly there is another candidate for the title – the storm’s little brother affectionately known as Great Red Spot Junior that appeared in 2000. It has grown since then so in the near future it may become the big brother and win the title of the biggest storm on Jupiter!

Image showing the GRS shrinking over the years The shrinking Great Red Spot on the right with Red Junior at the bottom left. Credit: NASA/ ESA