It’s Raining Mushballs on Jupiter


Here’s NASA’s explanation of this video: This animation takes the viewer high into a large storm high in Jupiter’s atmosphere, where a mushy water-ammonia particle (represented in green) descends through the atmosphere, collecting water ice in the process. The process creates a “mushball” – a special hailstone with a center made partially of liquid water-ammonia mush and a solid water-ice crust exterior. Within about 10 to 60 minutes (depending on their sizes), these mushballs reach Jupiter’s deeper layers, below the water clouds, where they rapidly melt and evaporate. Theoretical models predict these mushballs could grow to about 4 inches (10 centimeters) in diameter, weigh up to 2 pounds (1 kilogram), and reach speeds up to 450 mph (700 kph) during their descent.

Video Credit: NASA / JPL—Caltech / SwRI / MSSS / CNRS

The Star of Bethlehem


Roughly every twenty years, the paths of Jupiter and Saturn line up in the night sky, and the planets appear close together, an event called the Grand Conjunction. One occurs this evening. Look toward the southwest just after sunset, and if the sky is clear, you’ll see Jupiter and Saturn almost perfectly aligned, only about 0.1 degree apart. They haven’t come this close since 1623, but they were nearly aligned with the Sun and hard to see that year. The last time they were this close and relatively far from the Sun was in 1226.Grand Conjunctions occurred three times in 7 BC and again as a triple conjunction with Jupiter, Saturn, and Mars in early 6 BC. You can find more about those conjunctions and the Star of Bethlehem here.

You Can’t See This From Here


South Pole via CassiniThis view of Jupiter as seen from space above its south pole was constructed from images taken during the Cassini spacecraft’s flyby on the way to Saturn. When I first published this image in 2014, it was a rare view of Jupiter. Since then, the Juno spacecraft has been orbiting Jupiter and sending back views from almost every possible angle.

Image Credit: NASA

Jupiter in Visible Light and UV


From time to time, the Hubble Space Telescope takes observes the four gas giant planets in the Solar System in a ongoing survey of the outer planets’ weather systems. It took the last images of Jupiter in that series on 25 August. This video opens with a view of Jupiter in visible light. Then, a false-color UV view wipes across the planet, followed by a wipe back to visible light.

Video Credit: NASA

Ganymede’s North Pole


On 26 December, 2019, the Juno spacecraft’s orbit around Jupiter brought it near the north pole of the ninth-largest object in the solar system, the moon Ganymede. The spacecraft’s Jovian Infrared Auroral Mapper (JIRAM) instrument took the first infrared images of the massive moon’s north pole.

Ganymede only moon in the solar system that is larger than the planet Mercury. It’s mostly water ice. It is also the only moon in the solar system with its own magnetic field. On Earth, the magnetic field provides a pathway for plasma (charged particles from the Sun) to enter our atmosphere and create aurora. Ganymede has no atmosphere to impede the progress of those charged particle, so the surface at its poles is constantly being bombarded by plasma from Jupiter’s gigantic magnetosphere. The bombardment has a dramatic effect on Ganymede’s ice.

The ice near both poles of the moon is amorphous. This is cause by the impact of the plasma on the surface. That pounding prevents the ice from having a crystalline structure.

Image Credit: NASA/ JPL / SWRI / ASI / INAF

Smog on Jupiter?


The Juno spacecraft took this image of Jupiter’s northern latitudes during a close approach 17 February, 2020. Two long, thin bands run through the center of the image from top to bottom. Juno has observed these streaks since its first close pass over Jupiter in 2016. They are layers of haze particles floating above the cloud. We’re unsure of what these hazes are made of, or how they form. (There are no known SUVs on Jupiter.) There’s been speculation that jet streams in the planet’s atmospher may influence the formation of the hazes.

Image Credit: NASA / JPL / SwRI / MSSS
image processing by Gerald Eichstädt

Io and Jupiter


In Greek mythology Io was a priestess of Hera (Zeus’ wife) and a nymph who was seduced by Zeus. He changed her into a heifer to escape detection. Io is also the name of the innermost of the four Galilean moons of the planet Jupiter. The most volcanic body in the Solar System, Io is 3,600 kilometers in diameter, about the size of planet Earth’s moon.

While cruising past Jupiter at the turn of the millennium, the Cassini spacecraft captured this view of Io with Jupiter as a backdrop–offering an impressive demonstration of the ruling planet’s relative size. (An astronomer from another star system would probably describe our solar system as having one main planet and assorted debris.) Although Io appears to be located just in front of the swirling Jovian clouds, Io is about 350,000 km above Jupiter’s cloud tops. That’s roughly the same as the distance between Earth and Moon. The Cassini spacecraft itself was about 10 million km from Jupiter when this picture was taken.

Image Credit: NASA

Jupiter South


The Solar System can accurately described as the Sun, Jupiter, and assorted rubble. Indeed, Jupiter’s mass is more than twice that of all the remaining planets, moons, asteroid, comets, and leftovers.

This view of Jupiter’s southern hemisphere was stitched together from four images taken by the JunoCam on the Juno spacecraft on 17 February, 2020.

Image data: NASA / JPL-Caltech / SwRI / MSSS
Image processing by Kevin M. Gill, © CC

A Map of Jupiter


This map of Jupiter was assembled from images taken by Hubble. It’s a stretched-out map of the entire planet.

The Great Red Spot is the orange-colored oval on the left side of the image. This storm has a diameter slightly larger than the entire Earth’s. It appears more orange than red in this image, with a small core of deep-orange color at the center. Clouds moving toward the giant storm from right to left are darker than in earlier observations, and clouds to the south, which are moving toward the Great Red Spot from west to east, are whiter than in past studies. The Great Red Spot has been decreasing in size since the 19th Century. The weather changes on Jupiter, but on a vastly different time scale than here on Earth.

Red Spot Jr., a smaller storm than the Great Red Spot, has faded from red to white over the past couple of years. This storm is near the center of the map further south than its big cousin. Earth-based telescopes originally identified Red Spot Jr. as a white, oval-shaped storm created when three smaller ovals merged about 20 years ago. It turned red in 2005. Now, it has changed back to its original color.

Image Credit: NASA / STScI

Jupiter’s Magnetic Field


This animation illustrates Jupiter’s magnetic field at a single moment in time. The Great Blue Spot, an-invisible-to-the-eye concentration of magnetic field near the equator, stands out as a particularly strong feature. The gray lines (called field lines) show the field’s direction in space, and the depth of the color on the planet’s surface corresponds to the strength of the magnetic field. Dark red and dark blue correspond to strong positive and strong negative fields, respectively).

Video Credit: NASA