April 7, 2017
Jupiter has been a source of wonder since Italian astronomer Galileo Galilei first pointed his small telescope at the gas giant on January 7, 1610. Galileo saw only three of Jupiter's four large moons that night but he spotted the fourth the next night. And by watching their motions over several nights, he noticed that they shifted positions and determined they were indeed natural satellites of Jupiter. What would Galileo have thought of the detail we can see on the planet with even modest modern telescopes?
Spotting Jupiter, appearing as a bright creamy-colored star, is easy with the naked eye. However with a pair of binoculars or a telescope you can see much more details on the planet's upper atmosphere and even spot the four largest moons, Io, Europa, Ganymede, and Callisto. If you have a telescope, you’ll be able to not only see the moons as tiny points of light, but also begin to have the magnification and resolution toes Jupiter a a disk allowing you to investigate Jupiter’s atmospheric features such as cyclonic storms and dark cloud belts. Under clear, steady skies, a backyard telescope can reveal oval shaped, white-colored, cold ammonia ice zones mixed with darker belts of warmer currents . Even the famed Great Red Spot can be glimpsed at certain times, a giant hurricane-like storm that has been raging for three centuries and is two times the size of Earth.
Jupiter will be at opposition on April 7. This means it will be directly opposite the Sun from our point of view here in Earth. This is also the best time for viewing, as Jupiter will appear to dominate the overnight sky, rising in the east around the local sunset, gliding high across the high southern sky, and then eventually set in the west at around local sunrise. Joining Jupiter that night will be Spica, the blue-white star in the constellation Virgo, the maiden. Also nearby the pair will be the bright orange star Arcturus and even Earth's own, bright moon.
Sky and Telescope have a fantastic resource Jupiter: An Observing Guide, which will help you with your observations. NASA has some great resources for the planets of the solar system including Jupiter. The image on the right is from the Cassini Spacecraft (credit:NASA/JPL/University of Arizona)
Share your observations with us on Facebook or Twitter (@gam_awb) using #GAM2017 hashtag.
