Io, Io, It’s Off to Pluto We Go!

A plume rises from a volcano over Jupiter’s moon Io in this image taken by the New Horizons spacecraft. The volcano Tvashtar is marked by the bright glow  at the moon’s edge, beyond the day/night shadow line. The shadow of Io cuts across the plume itself. The image was recorded when the spacecraft was 2.3 million km from Io during a slingshot maneuver around Jupiter which provided a boost in the New Horizons‘ velocity for the spacecraft’s encounter Pluto in 2015 and the Kuiper Belt Object Arrokoth in 2019.

Image Credit: NASA

Listening to Ganymede

This animation provides auditory and visual presentations of data collected by the Juno spacecraft’s Waves instrument during a flyby of the Jovian moon Ganymede. The animation is shorter than the duration of the flyby because the Waves data is edited onboard to reduce telemetry requirements.

The abrupt change to higher frequencies around the midpoint of the recording occurs as the spacecraft moves from one region of Ganymede’s magnetosphere to another. The actual frequency range of the data is from 10 to 50 kHz. The animation audio has been shifted to a lower range audible to human ears.

Video Credit: NASA

Callisto

Callisto is the one of the Galilean moons of Jupiter, the second largest. Its surface is old, showing the highest coverage by impact craters of any large body in the Solar System, but it has no volcanoes or large mountains. Callisto’s surface is one large ice-field, littered with cracksand craters from billions of years of collisions. This picture was taken in 2001 by the Galileo spacecraft.

Image Credit: NASA

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.