The planet Jupiter is making its closest approach to Earth since 1951, growing so bright it is visible at twilight before the stars come out.
It won’t be this close until the year 2129, 107 years from now.
Here’s what’s happening: Jupiter is approaching a position in the solar system where it is in “opposition” to Earth, in the parlance of astronomers, which means directly opposite the sun as Earth passes between it and the sun. That’s reducing the distance between Earth and Jupiter every day. When it reaches conjunction on Sept. 26, it will be 366 million miles away. It can be as far as 600 million miles.
While Jupiter approaches earth at its opposition point every 13 months, there’s another reason the planet is so close and so bright. It also is approaching its “perihelion,” which is the closest it gets to the sun in its orbit. Jupiter reaches perihelion once every 12 Earth years, which is one reason so many years have passed since it was this close to Earth. Perihelion will occur in January.
“Jupiter isn’t always exactly closest to earth on the day of its opposition,” explains the astronomy site EarthSky. “But in 2022, Jupiter’s opposition to the sun and closest approach to earth fall on the same day. That’s because opposition takes place so near in time to Jupiter’s perihelion. If it’s nearly closest to the sun, and we go between it and the sun … it’s a close opposition for us. The juxtaposition of Jupiter’s opposition in late 2022, and perihelion in early 2023, brings the planet closer to earth at this opposition than it has been for 70 years.”
Currently, Jupiter becomes prominent in the eastern sky after sunset and crosses the sky overnight, remaining visible in the western sky at sunrise. It will rise above the eastern horizon later and later in the evening until it reaches opposition on Sept. 26, when it will rise right at sunset.
Jupiter is the largest planet in the solar system and typically is the third-brightest celestial object in the nighttime sky after the moon and Venus, according to Ron Hranac of the Denver Astronomical Society. The International Space Station can appear brighter than Venus and Jupiter, though, depending on where it is in its orbit.
According to Jeffrey Hunt, a retired Illinois planetarium director whose website (whenthecurveslineup.com) tracks easily observed celestial events for amateur sky gazers, Jupiter has grown 2.5 times brighter than it was last spring when it was in a position of “super conjunction,” meaning it was on the opposite side of the sun in relation to Earth.
“During April, Jupiter was 5.9 times Earth’s distance to the sun from us,” said Hunt, using a unit of measurement known as Astronomical Units, which are equivalent to the average distance between the Earth and the sun. “At opposition, the separation (will be) reduced to 3.9 times the Earth-sun distance.”
Jupiter has more than 70 moons, four of which were discovered by Galileo with a telescope in 1610, and some may become visible through binoculars as it grows closer to Earth this month.
If you’d like to view it through a telescope and don’t have one, the Sommers-Bausch Observatory at the University of Colorado hosts free public open houses on Fridays at 8 p.m., weather permitting. The observatory has several powerful telescopes visitors can use on open house nights, attended by CU faculty and students who are on hand to answer questions.
