September 23, 2022
Astronomy lovers can enjoy a spectacular view of the biggest planet in the solar system Monday night.
Jupiter is making its closest approach to Earth in 59 years, and it coincides with another phenomenon that will allow the gaseous giant to be seen all night long, NASA says.
That phenomenon, known as opposition, occurs when the Earth passes between the sun and a planet orbiting outside Earth's smaller, faster orbit. This places the sun and the planet on opposite sides of the Earth, causing the planet to rise in the east as the sun sets in the west. It then takes the planet all night to cross the sky.
Opposition only can occur among the five planets outside Earth's orbit – Mars, Jupiter, Saturn, Uranus and Neptune.
For Jupiter, opposition happens every 13 months. Yet, this rarely occurs when Jupiter is at its closest approach. That's why this year's event is considered so remarkable.
Earth and Jupiter pass one another at different distances because they don't orbit the sun in perfect circles. At its farthest, Jupiter is about 600 million miles away from Earth. On Monday, it will be about 367 million miles away, a proximity not reached since 1963.
The best way to view this phenomenon is to find a high elevation in a dark and dry area. In Philadelphia, the skies are expected to be mostly clear Monday night, according to the National Weather Service. But the spectacle will be visible for several days.
"The views should be great for a few days before and after Sept. 26," said Adam Kobelski, a research astrophysicist at NASA's Marshal Space Flight Center. "So, take advantage of good weather on either side of this date to take in the sight. Outside of the moon, it should be one of the (if not the) brightest objects in the night sky."
With binoculars, some of Jupiter's moons should be visible as bright dots, Kobelski said. But he recommended a larger telescope to see more details of the planet.
Scientists believe Jupiter has 79 moons, although only 53 have been named. Its four largest moons, named Galilean satellites after the man who first observed them in 1610, are Io, Europa, Ganymede and Callisto.
Jupiter is the fifth planet from the sun, and is more than twice as large as the seven other planets combined. What look like stripes and swirls covering Jupiter's surface are actually cold clouds of ammonia and water floating in an atmosphere of hydrogen and helium.
NASA's Juno space probe, which spans the width of a basketball court, is currently exploring the massive planet. It was launched from Earth in 2011 and made it to Jupiter in 2016. It will continue its mission there through 2025 or until the end of its life.
In June, Jupiter joined a "planet parade," a rare alignment of five planets that could be seen in the early morning sky.