June 26, 2017

Juno was the most powerful goddess of ancient Roman mythology. She was married to Jupiter, the king of the gods, and she was the queen. The Romans considered Juno a protector who would warn them of danger to their empire. Major shrines dedicated to Juno, Jupiter, and Minerva, the goddess of wisdom, stood on the Capitoline Hill, the religious center of ancient Rome. Juno’s shrine housed a flock of geese, which were sacred to the goddess. Legend claimed that the geese once saved Rome when their honking alerted the Romans to enemies sneaking up on the city.

A marble statue of Juno holding the golden apple of discord stands in a park in Sokyryntsi, Ukraine. Credit: © IMG Stock Studio/Shutterstock

Juno received special devotion from Roman women. She was the goddess of marriage, and her name may have been the source for the name of the month of June—still a popular month for marriages today. She was also the goddess of childbirth. In that role, she was called Juno Lucina, which means Juno Who Brings to Light.

Many stories about Juno come from Greek mythology. After the Romans came into contact with the Greeks, they identified Juno with Hera, the wife of Zeus, the king of the Greek gods. Although both Juno and Hera were goddesses of marriage, their own marriages were portrayed as rather stormy. Modern historians believe the reasons for this go back to ancient—very ancient—Greek history.

The hierarchy and worship of ancient Greek gods was not always as we understand it and label it today. People in different parts of ancient Greece often worshiped different gods, and only after cultures mixed were the religious traditions interwoven. In some areas, people had worshiped Hera for many generations before they ran into people who worshiped the sky god Zeus. Modern historians think the two religious traditions eventually merged, and this was expressed in mythical legends as a marriage between Hera and Zeus. The new people did not always get along, and thus neither did their gods. The legends further described other goddesses (and mortal women, too) as rivals for Zeus’s affections, and Hera came to be pictured as a jealous and vengeful wife. The Romans absorbed these stories into their own mythology, and they similarly portrayed Juno as a wife with many rivals who had to keep a watchful eye on her husband.

Juno’s watchful ways have not entirely disappeared, even today in the 21^st century. In 2011, NASA sent an unmanned spacecraft called Juno on a mission to Jupiter, the largest planet in our solar system. Juno arrived at Jupiter in 2016, and has since been observing the planet’s unique and often turbulent behavior. Juno remains as vigilant as ever.

June 9, 2017

Jupiter, our solar system’s largest planet, is slowly giving up its secrets. Last month, astronomers and planetary scientists of NASA’s Juno Mission to Jupiter released spectacular new images of the planet along with scientific papers fueled by the mission’s newly gathered data. The Juno probe has been in orbit around Jupiter since July 2016. NASA launched the spacecraft, named for the wife of the god Jupiter in Roman mythology, in August 2011. Juno is managed by the Jet Propulsion Laboratory in Pasadena, California.

Jupiter’s south pole, as seen by the Juno spacecraft from an altitude of 32,000 miles (52,000 kilometers). The oval features are massive cyclones up to 600 miles (1,000 kilometers) in diameter. Credit: NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles

Juno circles Jupiter in an unusual elongated (stretched out) orbit. Juno flies as far as 5 million miles (8 million kilometers) away from the planet and dives as close as 3,000 miles (5,000 kilometers) above Jupiter’s turbulent cloud tops. Rather than orbiting at or near the planet’s equator, Juno circles over Jupiter’s north and south poles. This orbit helps Juno avoid Jupiter’s radiation belt, which emanates from the planet’s waistline like an invisible ring. The intense radiation of this region would quickly destroy Juno’s electronic circuits and scientific instruments.

Spectacular storms cluster around Jupiter’s turbulent north pole. Credit: MSSS/SwRI/JPL-Caltech/NASA

Juno’s polar orbit has given scientists (and everyone else) new views of Jupiter. Unlike the rest of the planet’s atmosphere, which is famous for its banded structure (as we see in our familiar side view of the planet), Jupiter’s poles resemble bubbling cauldrons. Cyclonic storms many times larger than the largest hurricanes on Earth pockmark these regions, whose grayish-blue hues contrast with the tans, oranges, and reds found elsewhere on the planet. Scientists await further images to determine if these polar storms are short lived or if they may last years, decades, or even centuries—as has Jupiter’s famous and stormy Great Red Spot.

The familiar side view of Jupiter reveals its varied color bands and the Great Red Spot just south of the planet’s equator. Credit: Johns Hopkins U. APL/SWRI/NASA

One of Juno’s primary objectives is to study Jupiter’s internal makeup and determine if the planet has a solid, rocky core. The data returned so far suggest that Jupiter does indeed have a solid core, but that it is “fuzzy.” Data from future orbits of the probe will help scientists understand the makeup of the core and why it appears to have an undefined boundary.

Launched from Earth in 2011, the Juno spacecraft arrived at Jupiter in 2016. Credit: NASA/JPL

In addition to providing new looks at Jupiter, Juno has forced scientists to reconsider several previously believed notions of the giant planet. The probe has detected more ammonia in Jupiter’s atmosphere than was previously thought to be there. The ammonia is also spread unevenly, with much of it concentrating near Jupiter’s equator. Juno has discovered that the planet’s magnetic field is about as twice as strong as previously thought, and that the magnetism is “lumpy,” having stronger and weaker pockets. The magnetic field is also generated much closer to the planet’s surface than scientists had earlier guessed. Further measurements from Juno are needed to help understand how the field is generated. (Scientists think Earth’s magnetic field comes from the liquid core at our planet’s center.)

Juno still has more than 30 dives to collect information on Jupiter, providing numerous opportunities to further rewrite the book on our distant, gassy, and giant planetary neighbor.

July 5, 2016

Traditionally, Independence Day in the United States—yesterday, July 4—is celebrated with fireworks. This Fourth of July, the National Aeronautics and Space Administration (NASA) celebrated with fireworks of the deep space variety as its probe Juno fired its engine for 35 minutes to enter into orbit around Jupiter. After being launched in 2011, Juno has finally reached its destination.

Launched from Earth in 2011, the Juno spacecraft arrived at Jupiter on July 4, 2016, to study the giant planet from an elliptical polar orbit.
Credit: NASA/JPL

Jupiter is the largest planet in our solar system. It has a mass (amount of matter) that is greater than the masses of all the other planets in the solar system added together. Astronomers call Jupiter a gas giant because the planet consists mostly of hydrogen and helium, and it has no solid surface. Jupiter is named for the king of the gods in Roman mythology. Juno was Jupiter’s wife and queen of the gods.

Juno will study Jupiter from an elongated polar orbit. The probe will be 4,900 miles (7,200 kilometers) from Jupiter at the farthest point in its orbit, and dive to within 2,600 miles (4,200 kilometers) of the Jovian clouds, flying over the planet’s north and south poles. Mission scientists planned this orbit to keep Juno out of Jupiter’s radiation belts as much as possible. Jupiter emits a powerful magnetic field, much stronger than that produced by Earth. This strong magnetic field traps high-energy charged particles in belts around the planet. Any spacecraft entering these belts would be bombarded by huge doses of radiation. Such radiation is just as dangerous to electronics as it is to living things: it can damage computer chips and fry circuits.

Scientists shielded Juno’s most important electronics in a thick titanium case to protect them from radiation. But no spacecraft can stand exposure to such highly charged particles for long. NASA scientists do not expect the craft to survive much longer than its 20-month mission, even with its titanium vault and elliptical orbit. Consequently, they have already scheduled the probe to crash into Jupiter in February 2018.

Before it smashes into its object of study, Juno will probe the makeup of Jupiter. Scientists hope it will help determine whether Jupiter has a rocky core, and why the planet has a higher concentration of elements heavier than hydrogen and helium than the sun. Juno will also study Jupiter’s famous Great Red Spot, a storm that has been churning around the atmosphere for at least 300 years. Scientists think that answering these questions will help us better understand Jupiter’s history and the formation of our solar system. It may even give us a better idea of how other solar systems form and behave. Rather than a grand finale, Juno’s fireworks are the start of some amazing science!