Image Courtesy of NASA/JPL-Cal Tech
Observing Jupiter
Although Jupiter is more than twice as far away from the Sun as Mars, it is still probably even easier to observe due to its enormous size. It can be seen easily with the naked eye as a bright white point of light, and is regularly the fourth brightest object visible in the night sky (behind the Sun, the Moon, and Venus). It also appears brighter than Sirius which is the brightest star visible in the sky. When viewed through binoculars its shape and surface are visible as well as its four largest moons, Io, Europa, Ganymede, and Castillo. Viewing Jupiter through a telescope, one can see the details of its atmosphere containing large red and white bands of gas (the red ones are called belts while the white ones are called zones), as well as shadows cast by its moons on its surface. Jupiter rotates very quickly especially considering its size and if one looks closely enough it can be seen that this has a flattening effect on the planet causing it to be much wider at its equator. Also viewable through a telescope is the famous “Great Red Spot”, which is a storm that varies in size and intensity that has been present for at least 350 years. Jupiter’s constantly changing gaseous surfaces makes it a worthwhile planet to observe time and time again.
Finding Jupiter
Having an orbit further away from from any of the inner “terrestial planets” it moves much more slowly across the night sky and will appear to be in the same constellation (or area of the sky) for about a year at a time. The further a planet’s orbit is away from the Sun the slower it appears to move, thus making their location more constant and predictable in the night sky. However they become harder to observe well as they become more and more distant. In this way Jupiter is a great middle ground between these two factors, making it an ideal target for planetary observers. Due to its slower movement, once one locates Jupiter for the first time its location can be easily found again from night to night. The best time to view Jupiter, like all of the superior planets is when it is at opposition. Opposition between Jupiter and the Earth occurs once every 13 months. Check theAstronomical Calendar to see when Jupiter will be at opposition.
Facts About Jupiter
Average Distance from the Sun: 5.20 AU (778,300,000 km)
Orbital Period: 11.86 years
Length of Day: 9.8 hours
Mass: 1.90×1027 kg (317.8 Earth masses)
Diameter (equatorial): 142,800 km (11.19 times the earth)
Average Surface Temperature: -110°C / -166°F
