Jupiter is the fifth planet from the sun, and is a gas giant. The sun is one thousand times heavier than Jupiter, but Jupiter is two and a half times heavier than all of the other planets in our solar system put together! Jupiter is made up of hydrogen and helium, and has no defined outer surface. It may have a rocky inner core made up of metallic elements, but astronomers donвt know more about Jupiterвs core than this basic outline. The Great Red Spot is a large storm that has been going for hundreds of years (and possibly much longer). It was first observed by Giovanni Cassini, an Italian astronomer, during the 1600s. When Cassini first observed the Great Red Spot, it was a long, oval shape. This storm is so large, that it is up to two or three times bigger than Earth! The Great Red Spot is over 40,000 km in diameter, and could be seen easily with a telescope from your backyard. Even though the Great Red Spot is large now, it is slowly shrinking in size. The size of the Great Red Spot is half as wide as it was 100 years ago, and astronomers believe that it will be a round, circular shape by 2040.
Figure 1: Jupiterвs Great Red Spot. Image credit: NASA (public domain). Jupiterвs atmosphere is made up of hot gases that are constantly moving. These gases are rising and falling, and swirling throughout the atmosphere. Like on Earth, as cooler gas moves down through the atmosphere, the swirling intensifies, but there is no solid ground on Jupiter to slow it down. When the swirling gases merge into one another, they create giant circling storms. Astronomers believe that several giant storms came together and formed the Giant Red Spot. The Great Red Spot keeps going by drawing hot gases from above, and cooler gases from below. This keeps the storm in motion. Winds inside the storm are moving at a speed of 270 miles per hour (434 km per hour). The red colour of the Great Red Spot is thought to be caused by organic molecules, red phosphorous, or other elements that come from inside Jupiter. Some theories propose that the colour is caused by reactions between these chemicals in Jupiterвs atmosphere, or by lightning striking the molecules.
The colour is not always the same, either: sometimes it is dark red, while at other times it is a pale pink colour, or even white! Perhaps Jupiterвs Great Red Spot is not so red after all!
Jupiter\’s Great Red Spot may look sort of like a beauty mark on the gas giant planet, it\’s anything but. This massive, anti-cyclonic storm is twice as wide as Earth and was first discovered in 1665 by Italian astronomer Gian Domenico Cassini, who described seeing a \”permanent spot\” on the surface of Jupiter. Astronomers have been actively tracking the red oval since 1878, and report that it\’s been shrinking 580 miles per year in width — and may soon be a circle. What makes it red? Scientists used to think the color was caused by chemicals welling up from below the visible cloud layers, but new tests suggest something else is going on. Jupiter\’s atmosphere is composed almost entirely of hydrogen and helium, in roughly the same proportions as the Sun. Although other elements and compounds exist in tiny percentages, their effects are significant.
Recreating the conditions of the red spot, scientists in a lab took two of the trace compounds found in Jupiter\’s atmosphere, ammonia and acetylene, and exposed them to ultraviolet light as they would be in Jupiter\’s atmosphere. This produced a reddish gas that had a similar spectroscopic signature to gas found in the Great Red Spot, as measured by the Cassini spacecraft\’s December 2000 Jupiter flyby, providing evidence that the reddish color is confined to the uppermost region of the giant storm. So, in a way, the Great Red Spot could be thought of as, like, the worst sunburn in the Solar System. Since other trace gases in Jupiter\’s atmosphere, like ammonium hydrosulfide, turned green when exposed to UV light in a lab, this leaves the next question for chemists and astronomers to tackle: what combinations of elements are responsible for the swirling oranges, browns and reds that color Jupiter\’s atmosphere? Do you have any other questions about Jupiter that you\’d like for us to answer?
Please let us know by leaving a comment down below! Follow Amy on Twitter: r Read More: Jupiter\’s Atmosphere & the Great Red Spot r \”The atmosphere of Jupiter essentially makes up the entire planet. The gas giant has no firm surface to touch down on. Instead, it is composed almost entirely of hydrogen and helium, with a few traces of other gases comprising a tiny percentage of its air. \” Cassini Celebrates 10 Years Since Jupiter Encounter r \”Ten years ago, on Dec. 30, 2000, NASA\’s Cassini spacecraft made its closest approach to Jupiter on its way to orbiting Saturn. \” Jupiter\’s Great Red Spot Is Shrinking r \”Jupiter\’s trademark Great Red Spot — a swirling anti-cyclonic storm larger than Earth — has shrunk to its smallest size ever measured. \” Jupiter\’s Great Red Spot is likely a sunburn, not a blush r \”The ruddy color of Jupiter\’s Great Red Spot is likely a product of simple chemicals being broken apart by sunlight in the planet\’s upper atmosphere, according to a new analysis of data from NASA\’s Cassini mission. \”