I haven’t looked through a telescope in weeks. The second half of April seemed an endless string of cloudy nights and while I’m sure there were a few clear ones in there, one thing or another kept me from getting out under the stars with a telescope.
I am starting to miss observing and I can’t help but recall one of the last sessions of April, which happened to give the best views of Jupiter I’ve yet seen.
I was enjoying a pleasant evening out in the back yard with the kids when I first noticed Venus visible in the southwest and shortly after that was able to spot Jupiter, with some difficulty as the sky was still blue, near the zenith so I decided to bring out the 10″ Dob. Only a few weeks earlier I would’ve chosen a smaller scope but due to the mild weather that day I suspected the telescope would not need much, if any, cooling before being usable at high powers.
I was pleasantly surprised to learn that Ganymede was currently in the middle of a transit. Even better, the Great Red Spot was just appearing on the Eastern limb. I grabbed my smallest aperture telescope that takes interchangeable eyepieces, a 60mm refractor, and headed outside.
This month offers prime viewing for one of the most interesting objects in our Solar System as Jupiter is now well positioned for observation from twilight to dawn.
Jupiter is easily visible to the naked eye as the brightest star-like object in the sky. Currently it is found in Cancer, which can be a difficult constellation to locate in my suburban sky – look for it between Gemini and Leo.
Annotated picture of Jupiter taken by the Cassini spacecraft on December 29, 2000 (Credit NASA/JPL for original picture).
The planet offers a host of features for users of small telescopes. At powers around 10x the four Galilean moons can be seen nicely aligned with the planet. Increase the magnification to 40x and the main equatorial belts stand out clearly. Going to 100x and higher reveals more belts and zones.
For many observers of Jupiter the Great Red Spot (GRS), an enormous storm that has raged for hundreds of years, is a sought after highlight. Magnifications of around 130x are a good starting point for your first views of the GRS.