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Jupiter at Opposition

Jupiter, captured by the Hubble Space Telescope | NASA, ESA, A. Simon (Goddard Space Flight Center), and M.H. Wong (University of California, Berkeley)

By Claire Gibson, Lowell Educator

When looking up to the night sky, you may have noticed a large bright shining object in the Eastern sky. The object isn’t a UFO, it’s Jupiter! On September 26, 2022, Jupiter will be entering opposition. For the next few weeks, the giant planet will be at its biggest and brightest for the year for Earth observers. In anticipation for opposition, here are some fun facts about Jupiter and opposition.

What is Opposition? 

Opposition occurs in astronomy when a planet moves into a position directly opposite the Sun in the solar system. Thus, from Earth, the planet appears as its biggest and brightest self in the sky. 

Jupiter at Opposition

Jupiter’s Giant Satellites

Jupiter has 79 satellites, or moons, taking second place next to Saturn with the most moons (a total of 82!). Four of these moons are some of the most well known in the solar system. The four Galilean moons Europa, Ganymede, Callisto, and Io were discovered by Galileo in 1610, becoming the first moons to be known outside of our own Moon. To an observer with a small telescope or a pair of night sky binoculars, these four moons will look like prominent points of light in a neat line aligned with the equator of Jupiter. Sometimes, you may see less than four moons, as they may be passing in front of or behind Jupiter. 

Jupiter’s Colored Stripes

Why does Jupiter have such distinctive features? To an observer with a telescope, you can see clear bands on the surface of Jupiter. The cause of these bands has to do with atmospheric dynamics. There are two types of bands on Jupiter. First, there are zones, which are the light colored bands on the surface. Next, there are belts, which are the darker rusty colored bands. Color differences are caused by slight variations in the composition of the gasses in the bands. Although Jupiter is mostly made of hydrogen and helium, there are other trace elements and molecules such as water, ammonia, and methane. When looking at a detailed image of the surface of Jupiter’s atmosphere, there are bands that can be right next to each other, but still have a distinct ‘stripe’. This is caused by winds moving in different directions in zones right next to each other!

Future Missions to Jupiter

Soon, Jupiter will be visited by upcoming solar system missions. One of them is the Europa Clipper mission, which will predominantly study the large moon Europa to study the composition and dynamics of materials on and below the surface of this icy (and potentially life-harboring) moon. Another mission, called JUpiter ICy moons Explorer (JUICE), will study both Jupiter and the icy moons of Jupiter including Ganymede and Callisto. 

Colorful Aurora

Similar to Earth, Jupiter also has aurora, caused by the interaction of charged particles that have traveled from the Sun to meet Jupiter’s magnetic field. Recently, a new James Webb Space Telescope has imaged the aurora of Jupiter in a way that astronomers and the public have never seen before. In the image, the aurora looks orange, indicating longer wavelengths of light. The JWST is an infrared telescope, and thus visible light wavelengths are assigned to the infrared wavelengths so that we can visually interpret the data. Check it out!

Image Credit: Credit: NASA, ESA, CSA, Jupiter ERS Team; image processing by Judy Schmidt.

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