Tonight! Great Red Spot transits Jupiter joined by Europa with it’s shadow falling on Jupiter’s cloud tops

Update (Sunday 5 January 2014): Managed to spot the ‘Great Salmon Spot’ 🙂 using my amateur sized telescope but it was difficult because of Jupiter’s low altitude and its subtle colour. Europa was definitely not visible against the brighter disc of Jupiter nor was Europa’s shadow visible. The later was not a surprise in retrospect given that Jupiter reaches opposition tomorrow meaning that there really shouldn’t be a shadow visible (with Jupiter, Europa and the Earth effectively being in a straight line meaning that Europa’s shadow should be behind Europa from Earth’s viewpoint).

Original post (Sunday 5 January 2014): Look low above the North Eastern horizon tonight as soon as the sky is dark and you will notice a dazzling bright star. Point even a very small telescope at the ‘star’ and you will discover that you are looking at the largest planet in our solar system, Jupiter. If you do have a small telescope, look at Jupiter again tonight around 9:42 pm AEST / 10:42 pm AEDT to watch as Jupiter’s moon Europa crosses the face of Jupiter. I will be out watching to see if Europa’s shadow falling on the cloud tops of Jupiter does create a 3D like effect like that indicated below in the chart.

A second reason for looking at Jupiter is the chance to see the largest storm in our solar system, the Great Red Spot. Not only is is it a very old storm (hundreds of years), it is very large at about 12,000 by 25,000 km and is big enough to hold two Earths. Sadly the colour has faded in the last few years and it should really be called the Great Salmon Spot! Given that Jupiter rotates approximately every 9 hours and 50 minutes, you have to know when to look for it. I use this handy webpage which calculates what astronomers the Great Red Spot’s transit times (i.e. when it passes across the face of Jupiter as seen from Earth). Tonight, it transits at 9:42 am AEST / 10:42 pm AEDT.

Finally, if you are not sure where to point your telescope, refer to the below wide angle finder chart. Essentially, look to the North East (low above the horizon) as soon as the sky is dark and look for the brightest star you can see in the night sky. That star is really the planet Jupiter.