  Since 990 is divisible by ten, the answer is 990. If you were rounding off 994 the answer would also be 990. If you were rounding off 995, the answer would be 1,000.
Jupiter is the largest and most massive planet in the solar system. It was named after the chief Roman god. It is a gas giant composed of liquid and gaseous matter, and has many moons. Some of the storms in its atmosphere have lasted hundreds of years.
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.