Astronomy Essentials

Neptune at opposition September 16, 2022

Posted by

and

September 16, 2022

Green line of ecliptic with marks indicating location of Neptune, with large dot for Jupiter. — Neptune at opposition, when it lies opposite the sun in the sky. Neptune is also at its nearest point from Earth being nearly 3 billion miles (nearly 5 billion km) distant. The planet is still so far away, though, that it will be visible only through good binoculars or telescopes. Immediately east of invisible Neptune shines bright Jupiter. Chart via John Jardine Goss / EarthSky.

Earth will sweep between the sun and Neptune on September 16, 2022, placing the distant planet opposite the sun in our sky.

Neptune at opposition in 2022

When and where to watch in 2022: Neptune emerged in the east before sunrise by April 2022 and is visible in good binoculars or a telescope in the morning sky through mid-September. By the time of its September 16 opposition, Neptune is rising in the east at sunset and visible all night. For the rest of 2022, Neptune is up in the evening. It remains visible in good binoculars or a telescope in the evening sky through January of 2023.
Opposition for Neptune will fall at 23 UTC on September 16, 2022.
Note: Opposition marks the middle of the best time of year to see an outer planet. Neptune reaches a yearly maximum in brightness at or near opposition. From mid-July to mid-November, Neptune will be at its brightest but it won’t be visible to the unaided eye. Think of us on Earth, sweeping between the sun and Neptune in our smaller, faster orbit. Around the same time as Neptune reaches opposition, it is also making its closest approach to Earth.

Complex diagram with sun at center, ring with Earth in orbit and outer planet ring showing opposition. — During opposition, an outer planet or solar system object is opposite the sun in Earth’s sky. Chart via John Jardine Goss / EarthSky.

Quick facts about Neptune at opposition

Neptune is in front of the constellation Aquarius the Water Bearer.

The 8th planet shines at its brightest for 2022, at magnitude +7.8.

Neptune is at its least distance from Earth for 2022, 240 light-minutes from Earth.

Through a telescope, Neptune appears 2.34 arcseconds across. Neptune’s brightest moon, Triton, is visible in medium size telescopes.

Through binoculars, Neptune will appear as a star-like object if you know where to find it.

For precise sun and Neptune rising times at your location:

Old Farmer’s Almanac (U.S. and Canada)

Timeanddate.com (worldwide).

Stellarium (online planetarium program)

How often is Neptune at opposition?

Neptune is the eighth planet from our sun. A year on Neptune is 165 Earth-years long. Because Neptune’s orbit around the sun is so gigantic, and because Earth whips around the sun so quickly in comparison, Neptune’s opposition date comes only a few days later each year.

2022 Neptune opposition – September 16
2023 Neptune opposition – September 19
2024 Neptune opposition – September 20
2025 Neptune opposition – September 23

Neptune events in 2022 and 2023

June 28, 2022: Neptune begins retrograde motion
Septemper 16, 2022: Neptune at opposition
December 3, 2022: Neptune ends retrograde motion
March 15, 2023: Neptune at solar conjunction
June 30, 2023: Neptune begins retrograde motion
September 1, 2023: Lunar occultation of Neptune
September 19, 2023: Neptune at opposition

Round medium almost featureless planet with a few white streaks and a slightly darker large oval. — In 1989, NASA’s Voyager 2 became the first spacecraft to observe Neptune. Image via NASA. See more images from Voyager.

Earth and Neptune

Earth and Neptune are generally closest around its opposition. In 2022, Earth and Neptune come closest for the year the day before opposition, on September 15. If Earth and Neptune both orbited the sun in perfect circles and on the same plane, then Neptune would be closest to Earth at opposition. But, in 2022, Earth comes closest to Neptune about 20 hours before opposition. By the time opposition rolls around, Earth is a bit closer to the sun (and, therefore, farther from Neptune).

As we come closest to Neptune for the year, we don’t mean close. At opposition, Neptune’s distance is about approximately 2.7 billion miles (4.3 billion km). Visit Heavens-above to know Neptune’s present distance in astronomical units.

You need optical aid to see Neptune

Planets are brightest when at opposition. But Neptune, the eighth planet, is never truly bright. It’s the only major solar system planet that’s never visible to the unaided eye. This world is about five times fainter than the dimmest star you can see on a moonless night under dark skies. You’ll need binoculars or a telescope for Neptune, plus a detailed sky chart.

Because we’re more or less between Neptune and the sun around now, Neptune is rising in the east around the time of sunset, climbing highest up for the night around midnight and setting in the west around sunrise. As viewed from Earth now, this world is in front of the constellation Aquarius the Water Bearer, look for it below the Circlet of Pisces and to the right of Jupiter.

Even with optical aid, Neptune may look like a faint star. You need to magnify Neptune by about 200 times and have a steady night of seeing to view this distant world as a small disk.

Bottom line: Neptune at opposition – when it’s 180 degrees from the sun on the sky’s dome – comes on September 16, 2022. You need optical aid to spot it.

Posted

September 16, 2022

in

Astronomy Essentials

Bruce McClure

View Articles

About the Author:

Bruce McClure served as lead writer for EarthSky's popular Tonight pages from 2004 to 2021, when he opted for a much-deserved retirement. He's a sundial aficionado, whose love for the heavens has taken him to Lake Titicaca in Bolivia and sailing in the North Atlantic, where he earned his celestial navigation certificate through the School of Ocean Sailing and Navigation. He also wrote and hosted public astronomy programs and planetarium programs in and around his home in upstate New York.