With Jupiter we are really beginning to move into the outer solar system. Jupiter is a long way from the Earth, even at opposition (~390 million miles/626 million km), but it is so big (11 times the diameter of the Earth) that is the largest planet you will observe or image with a telescope. Small planets such as Mars are best viewed within a few weeks of their opposition, but Jupiter is worth a look no matter when you can see it in the night sky.
Jupiter has 53 confirmed satellites/moons (as many as 16 more are awaiting confirmation), but only the largest four, first observed by Galileo ver 400 years ago, are routinely visible in amateur telescopes.
When you look at Jupiter, you are not seeing the solid surface of the planet. Instead, you are looking at the the very high tops of clouds that essentially block any view of what lies beneath. However, those clouds are highly varied and dynamic and well-worth observing. What you are seeing is a grand case of weather, a global heat machine unrivaled in the solar system.The modest heat from the sun combines with the very significant internal heat of the planet itself to keep the atmosphere continuous churning, while the very fast rotational speed (a day on Jupiter is only about ten hours long) adds to the mix of forces acting on the atmosphere. The broad latitudinal bands of clouds owe their color differences to the mix of gasses and although the bands are usually somewhat stable, even they can change with time. The largest single storm on the planet, the Great Red Spot, is a hurricane-like weather system the size of the Earth which has persisted (at varying intensity) for several centuries. Click on Jupiter on the [NASA Solar System Exploration] page for much more information on this giant of the Solar System.
This image was obtained one day after opposition in 2017 and on the actual day of closest approach to the Earth. The Long-awaited OMC200 telescope was still weeks from delivery and this image was obtained using a 180 mm Maksutov/Cassegrain (f/17) marketed by [Orion Telescopes and Binoculars] in California. If you are looking for an excellent serious starter instrument for Lunar and Planetary imaging, you cannot get a better price/performance ratio. This image clearly shows a great deal of cloud detail, the Great Red Spot, and Europa and Ganymede, two of the Galilean satellites. The diameter of Ganymede is approximately 1.7 times larger than that of Europa – a difference clearly evident in the image.
“First-light” image of Jupiter following the installation of the Orion Optics UK OMC200 instrument. The difference in relative size of the image disc is a consequence of the larger focal ratio of the OMC200 (f/20) compared to that of the 180 mm Maksutov (f/17).
2018 Jupiter Opposition
Jupiter will reach opposition with the Earth (essentially its closest approach for the year) on 09 May 2018. Jupiter is large enough that it should provide excellent views for several months on either side of opposition. As new images are acquired this Spring, they will be posted here.
03 Feb 2018 Update:
Jupiter, with an apparent diameter of 35 arc-sec. reaches an elevation of about 30 degrees in the southern sky about a hour prior to sunrise. While it should be easy to image the planet, the rare clear skies come with very low temperatures – about 0 F! Neither the computer or I do well at those temperatures, so serious imaging will have to wait until the weather warms a bit.